Edoardo Bossini

TOTEM has measured the differential cross-section for elastic proton-proton scattering at the LHC energy of analysing data from a short run with dedicated large-β* optics. A single exponential fit with a slope B=(20.1±0.2stat±0.3syst) GeV−2 describes the range of the four-momentum transfer squared |t| from 0.02 to 0.33 GeV2. After the extrapolation to |t|=0, a total elastic scattering cross-section of (24.8±0.2stat±1.2syst) mb was obtained. Applying the optical theorem and using the luminosity measurement from CMS, a total proton-proton cross-section of (98.3±0.2stat±2.8syst) mb was deduced which is in good agreement with the expectation from the overall fit of previously measured data over a large range of center-of-mass energies. From the total and elastic pp cross-section measurements, an inelastic pp cross-section of was inferred.

At the LHC energy of , under various beam and background conditions, luminosities, and Roman Pot positions, TOTEM has measured the differential cross-section for proton-proton elastic scattering as a function of the four-momentum transfer squared t. The results of the different analyses are in excellent agreement demonstrating no sizeable dependence on the beam conditions. Due to the very close approach of the Roman Pot detectors to the beam center (≈5σbeam) in a dedicated run with β* = 90 m, |t|-values down to 5·10−3 GeV2 were reached. The exponential slope of the differential elastic cross-section in this newly explored |t|-region remained unchanged and thus an exponential fit with only one constant B = (19.9 ± 0.3) GeV−2 over the large |t|-range from 0.005 to 0.2 GeV2 describes the differential distribution well. The high precision of the measurement and the large fit range lead to an error on the slope parameter B which is remarkably small compared to previous experiments. It allows a precise extrapolation over the non-visible cross-section (only 9%) to t = 0. With the luminosity from CMS, the elastic cross-section was determined to be (25.4 ± 1.1) mb, and using in addition the optical theorem, the total pp cross-section was derived to be (98.6 ± 2.2) mb. For model comparisons the t-distributions are tabulated including the large |t|-range of the previous measurement (TOTEM Collaboration (Antchev G. et al), EPL, 95 (2011) 41001).

The TOTEM collaboration has measured the proton-proton total cross section at √s=8 TeV using a luminosity-independent method. In LHC fills with dedicated beam optics, the Roman pots have been inserted very close to the beam allowing the detection of ~90% of the nuclear elastic scattering events. Simultaneously the inelastic scattering rate has been measured by the T1 and T2 telescopes. By applying the optical theorem, the total proton-proton cross section of (101.7±2.9) mb has been determined, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: σ(el)=(27.1±1.4) mb; σ(inel)=(74.7±1.7) mb.

The TOTEM experiment at the LHC has performed the first luminosity-independent determination of the total proton-proton cross-section at . This technique is based on the optical theorem and requires simultaneous measurements of the inelastic rate – accomplished with the forward charged-particle telescopes T1 and T2 in the range 3.1 < |η| < 6.5 – and of the elastic rate by detecting the outcoming protons with Roman Pot detectors. The data presented here were collected in a dedicated run in 2011 with special beam optics (β* = 90 m) and Roman Pots approaching the beam close enough to register elastic events with squared four-momentum transfers |t| as low as 5·10−3 GeV2. The luminosity-independent results for the elastic, inelastic and total cross-sections are σel = (25.1 ± 1.1) mb, σinel = (72.9 ± 1.5) mb and σtot = (98.0 ± 2.5) mb, respectively. At the same time this method yields the integrated luminosity, in agreement with measurements by CMS. TOTEM has also determined the total cross-section in two complementary ways, both using the CMS luminosity measurement as an input. The first method sums the elastic and inelastic cross-sections and thus does not depend on the ρ parameter. The second applies the optical theorem to the elastic-scattering measurements only and therefore is free of the T1 and T2 measurement uncertainties. The methods, having very different systematic dependences, give results in excellent agreement. Moreover, the ρ-independent measurement makes a first estimate for the ρ parameter at possible: |ρ| = 0.145 ± 0.091.

The TOTEM experiment has made a precise measurement of the elastic proton–proton differential cross-section at the centre-of-mass energy s=8TeV based on a high-statistics data sample obtained with the β⁎=90m optics. Both the statistical and systematic uncertainties remain below 1%, except for the t-independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027<|t|<0.2GeV2 with a significance greater than 7σ. Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data. Using them for the differential cross-section extrapolation to t=0, and further applying the optical theorem, yields total cross-section estimates of (101.5±2.1)mb and (101.9±2.1)mb, respectively, in agreement with previous TOTEM measurements.

The goal of this report is to give a comprehensive overview of the rich field of forward physics, with a special attention to the topics that can be studied at the LHC. The report starts presenting a selection of the Monte Carlo simulation tools currently available, chapter 2, then enters the rich phenomenology of QCD at low, chapter 3, and high, chapter 4, momentum transfer, while the unique scattering conditions of central exclusive production are analyzed in chapter 5. The last two experimental topics, Cosmic Ray and Heavy Ion physics are presented in the chapter 6 and 7 respectively. Chapter 8 is dedicated to the BFKL dynamics, multiparton interactions, and saturation. The report ends with an overview of the forward detectors at LHC. Each chapter is correlated with a comprehensive bibliography, attempting to provide to the interested reader with a wide opportunity for further studies.

The TOTEM experiment at the CERN LHC has measured elastic proton–proton scattering at the centre-of-mass energy $$\sqrt{s}=8\,$$ TeV and four-momentum transfers squared, |t|, from $$6\times 10^{-4}$$ to 0.2 GeV $$^{2}$$ . Near the lower end of the t-interval the differential cross-section is sensitive to the interference between the hadronic and the electromagnetic scattering amplitudes. This article presents the elastic cross-section measurement and the constraints it imposes on the functional forms of the modulus and phase of the hadronic elastic amplitude. The data exclude the traditional Simplified West and Yennie interference formula that requires a constant phase and a purely exponential modulus of the hadronic amplitude. For parametrisations of the hadronic modulus with second- or third-order polynomials in the exponent, the data are compatible with hadronic phase functions giving either central or peripheral behaviour in the impact parameter picture of elastic scattering. In both cases, the $$\rho $$ -parameter is found to be $$0.12 \pm 0.03$$ . The results for the total hadronic cross-section are $$\sigma _\mathrm{tot} = (102.9 \pm 2.3)$$ mb and $$(103.0 \pm 2.3)$$ mb for central and peripheral phase formulations, respectively. Both are consistent with previous TOTEM measurements.

The TOTEM collaboration has measured the proton–proton total cross section at $$\sqrt{s}=13~\hbox {TeV}$$ with a luminosity-independent method. Using dedicated $$\beta ^{*}=90~\hbox {m}$$ beam optics, the Roman Pots were inserted very close to the beam. The inelastic scattering rate has been measured by the T1 and T2 telescopes during the same LHC fill. After applying the optical theorem the total proton–proton cross section is $$\sigma _\mathrm{tot}=(110.6~\pm ~3.4$$ ) mb, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: $$\sigma _\mathrm{el}=(31.0~\pm ~1.7)~\hbox {mb}$$ and $$\sigma _\mathrm{inel}=(79.5~\pm ~1.8)~\hbox {mb}$$ .

Abstract The TOTEM experiment at the LHC has performed the first measurement at $$\sqrt{s} = 13\,\mathrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>13</mml:mn><mml:mspace /><mml:mi>TeV</mml:mi></mml:mrow></mml:math> of the $$\rho $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>ρ</mml:mi></mml:math> parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at $$t=0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>t</mml:mi><mml:mo>=</mml:mo><mml:mn>0</mml:mn></mml:mrow></mml:math> , obtaining the following results: $$\rho = 0.09 \pm 0.01$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>ρ</mml:mi><mml:mo>=</mml:mo><mml:mn>0.09</mml:mn><mml:mo>±</mml:mo><mml:mn>0.01</mml:mn></mml:mrow></mml:math> and $$\rho = 0.10 \pm 0.01$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>ρ</mml:mi><mml:mo>=</mml:mo><mml:mn>0.10</mml:mn><mml:mo>±</mml:mo><mml:mn>0.01</mml:mn></mml:mrow></mml:math> , depending on different physics assumptions and mathematical modelling. The unprecedented precision of the $$\rho $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>ρ</mml:mi></mml:math> measurement, combined with the TOTEM total cross-section measurements in an energy range larger than $$10\,\mathrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>10</mml:mn><mml:mspace /><mml:mi>TeV</mml:mi></mml:mrow></mml:math> (from 2.76 to $$13\,\mathrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>13</mml:mn><mml:mspace /><mml:mi>TeV</mml:mi></mml:mrow></mml:math> ), has implied the exclusion of all the models classified and published by COMPETE. The $$\rho $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>ρ</mml:mi></mml:math> results obtained by TOTEM are compatible with the predictions, from other theoretical models both in the Regge-like framework and in the QCD framework, of a crossing-odd colourless 3-gluon compound state exchange in the t -channel of the proton–proton elastic scattering. On the contrary, if shown that the crossing-odd 3-gluon compound state t -channel exchange is not of importance for the description of elastic scattering, the $$\rho $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>ρ</mml:mi></mml:math> value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-| t | reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton–proton cross-section measurement $$\sigma _{\mathrm{tot}} = (110.3 \pm 3.5)\,\mathrm{mb}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>σ</mml:mi><mml:mi>tot</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mrow><mml:mo>(</mml:mo><mml:mn>110.3</mml:mn><mml:mo>±</mml:mo><mml:mn>3.5</mml:mn><mml:mo>)</mml:mo></mml:mrow><mml:mspace /><mml:mi>mb</mml:mi></mml:mrow></mml:math> , completely independent from the previous TOTEM determination. Combining the two TOTEM results yields $$\sigma _{\mathrm{tot}} = (110.5 \pm 2.4)\,\mathrm{mb}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>σ</mml:mi><mml:mi>tot</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mrow><mml:mo>(</mml:mo><mml:mn>110.5</mml:mn><mml:mo>±</mml:mo><mml:mn>2.4</mml:mn><mml:mo>)</mml:mo></mml:mrow><mml:mspace /><mml:mi>mb</mml:mi></mml:mrow></mml:math> .

We describe an analysis comparing the $p\overline{p}$ elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that in $pp$ collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13 TeV using a model-independent approach. The TOTEM cross sections, extrapolated to a center-of-mass energy of $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$, are compared with the D0 measurement in the region of the diffractive minimum and the second maximum of the $pp$ cross section. The two data sets disagree at the $3.4\ensuremath{\sigma}$ level and thus provide evidence for the $t$-channel exchange of a colorless, $C$-odd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of the same $C$-odd exchange based on the total cross section and the ratio of the real to imaginary parts of the forward elastic strong interaction scattering amplitude in $pp$ scattering for which the significance is between $3.4\ensuremath{\sigma}$ and $4.6\ensuremath{\sigma}$. The combined significance is larger than $5\ensuremath{\sigma}$ and is interpreted as the first observation of the exchange of a colorless, $C$-odd gluonic compound.

The TOTEM experiment at the LHC has measured the inelastic proton-proton cross-section at in a β* = 90 m run with low inelastic pile-up. The measurement was based on events with at least one charged particle in the T2 telescope acceptance of 5.3 < |η| < 6.5 in pseudorapidity. Combined with data from the T1 telescope, covering 3.1 < |η| < 4.7, the cross-section for inelastic events with at least one |η| ⩽ 6.5 final-state particle was determined to be (70.5 ± 2.9) mb. This cross-section includes all central diffractive events of which maximally 0.25 mb is estimated to escape the detection of the telescopes. Based on models for low mass diffraction, the total inelastic cross-section was deduced to be (73.7 ± 3.4) mb. An upper limit of 6.31 mb at 95% confidence level on the cross-section for events with diffractive masses below 3.4 GeV was obtained from the difference between the overall inelastic cross-section obtained by TOTEM using elastic scattering and the cross-section for inelastic events with at least one |η| ⩽ 6.5 final-state particle.

Abstract The TOTEM collaboration has measured the elastic proton-proton differential cross section $$\mathrm{d}\sigma /\mathrm{d}t$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>d</mml:mi><mml:mi>σ</mml:mi><mml:mo>/</mml:mo><mml:mi>d</mml:mi><mml:mi>t</mml:mi></mml:mrow></mml:math> at $$\sqrt{s}=13$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>13</mml:mn></mml:mrow></mml:math> TeV LHC energy using dedicated $$\beta ^{*}=90$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mi>β</mml:mi><mml:mrow><mml:mrow /><mml:mo>∗</mml:mo></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mn>90</mml:mn></mml:mrow></mml:math> m beam optics. The Roman Pot detectors were inserted to 10 $$\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>σ</mml:mi></mml:math> distance from the LHC beam, which allowed the measurement of the range [0.04 GeV $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mn>2</mml:mn></mml:msup></mml:math> ; 4 GeV $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mn>2</mml:mn></mml:msup></mml:math> $$]$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>]</mml:mo></mml:math> in four-momentum transfer squared | t |. The efficient data acquisition allowed to collect about 10 $$^{9}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mn>9</mml:mn></mml:msup></mml:math> elastic events to precisely measure the differential cross-section including the diffractive minimum (dip), the subsequent maximum (bump) and the large-| t | tail. The average nuclear slope has been found to be $$B=(20.40 \pm 0.002^{\mathrm{stat}} \pm 0.01^{\mathrm{syst}})~$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>B</mml:mi><mml:mo>=</mml:mo><mml:mo>(</mml:mo><mml:mn>20.40</mml:mn><mml:mo>±</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>002</mml:mn><mml:mi>stat</mml:mi></mml:msup><mml:mo>±</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>01</mml:mn><mml:mi>syst</mml:mi></mml:msup><mml:mo>)</mml:mo><mml:mspace /></mml:mrow></mml:math> GeV $$^{-2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mrow><mml:mo>-</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:math> in the | t |-range 0.04–0.2 GeV $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mn>2</mml:mn></mml:msup></mml:math> . The dip position is $$|t_{\mathrm{dip}}|=(0.47 \pm 0.004^{\mathrm{stat}} \pm 0.01^{\mathrm{syst}})~$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mrow><mml:mo>|</mml:mo></mml:mrow><mml:msub><mml:mi>t</mml:mi><mml:mi>dip</mml:mi></mml:msub><mml:mrow><mml:mo>|</mml:mo><mml:mo>=</mml:mo></mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mn>0.47</mml:mn><mml:mo>±</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>004</mml:mn><mml:mi>stat</mml:mi></mml:msup><mml:mo>±</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>01</mml:mn><mml:mi>syst</mml:mi></mml:msup><mml:mo>)</mml:mo></mml:mrow><mml:mspace /></mml:mrow></mml:math> GeV $$^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mn>2</mml:mn></mml:msup></mml:math> . The differential cross section ratio at the bump vs. at the dip $$R=1.77\pm 0.01^{\mathrm{stat}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>R</mml:mi><mml:mo>=</mml:mo><mml:mn>1.77</mml:mn><mml:mo>±</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:msup><mml:mn>01</mml:mn><mml:mi>stat</mml:mi></mml:msup></mml:mrow></mml:math> has been measured with high precision. The series of TOTEM elastic pp measurements show that the dip is a permanent feature of the pp differential cross-section at the TeV scale.

Abstract The proton–proton elastic differential cross section $${\mathrm{d}}\sigma /{\mathrm{d}}t$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>d</mml:mi><mml:mi>σ</mml:mi><mml:mo>/</mml:mo><mml:mi>d</mml:mi><mml:mi>t</mml:mi></mml:mrow></mml:math> has been measured by the TOTEM experiment at $$\sqrt{s}=2.76\hbox { TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>2.76</mml:mn><mml:mspace /><mml:mtext>TeV</mml:mtext></mml:mrow></mml:math> energy with $$\beta ^{*}=11\hbox { m}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mi>β</mml:mi><mml:mrow><mml:mrow /><mml:mo>∗</mml:mo></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mn>11</mml:mn><mml:mspace /><mml:mtext>m</mml:mtext></mml:mrow></mml:math> beam optics. The Roman Pots were inserted to 13 times the transverse beam size from the beam, which allowed to measure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer (| t |) from 0.36 to $$0.74\hbox { GeV}^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0.74</mml:mn><mml:mspace /><mml:msup><mml:mtext>GeV</mml:mtext><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math> . The differential cross-section can be described with an exponential in the | t |-range between 0.36 and $$0.54\hbox { GeV}^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0.54</mml:mn><mml:mspace /><mml:msup><mml:mtext>GeV</mml:mtext><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math> , followed by a diffractive minimum (dip) at $$|t_{\mathrm{dip}}|=(0.61\pm 0.03)\hbox { GeV}^{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mrow><mml:mo>|</mml:mo></mml:mrow><mml:msub><mml:mi>t</mml:mi><mml:mi>dip</mml:mi></mml:msub><mml:mrow><mml:mo>|</mml:mo><mml:mo>=</mml:mo><mml:mrow><mml:mo>(</mml:mo><mml:mn>0.61</mml:mn><mml:mo>±</mml:mo><mml:mn>0.03</mml:mn><mml:mo>)</mml:mo></mml:mrow><mml:mspace /></mml:mrow><mml:msup><mml:mtext>GeV</mml:mtext><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math> and a subsequent maximum (bump). The ratio of the $${\mathrm{d}}\sigma /{\mathrm{d}}t$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>d</mml:mi><mml:mi>σ</mml:mi><mml:mo>/</mml:mo><mml:mi>d</mml:mi><mml:mi>t</mml:mi></mml:mrow></mml:math> at the bump and at the dip is $$1.7\pm 0.2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1.7</mml:mn><mml:mo>±</mml:mo><mml:mn>0.2</mml:mn></mml:mrow></mml:math> . When compared to the proton–antiproton measurement of the D0 experiment at $$\sqrt{s} = 1.96\hbox { TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>1.96</mml:mn><mml:mspace /><mml:mtext>TeV</mml:mtext></mml:mrow></mml:math> , a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for the exchange of a colourless C-odd three-gluon compound state in the t -channel of the proton–proton and proton–antiproton elastic scattering.

The first double diffractive cross-section measurement in the very forward region has been carried out by the TOTEM experiment at the LHC with center-of-mass energy of sqrt(s)=7 TeV. By utilizing the very forward TOTEM tracking detectors T1 and T2, which extend up to |eta|=6.5, a clean sample of double diffractive pp events was extracted. From these events, we measured the cross-section sigma_DD =(116 +- 25) mub for events where both diffractive systems have 4.7 <|eta|_min < 6.5 .

As the LHC luminosity is ramped up to 3 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\,\times 10^{34}~{\hbox {cm}}^{2}~s^{1}$</tex></formula> and beyond, the high rates, multiplicities, and energies of particles seen by the detectors will pose a unique challenge. Only a tiny fraction of the produced collisions can be stored offline and immense real-time data reduction is needed. An effective trigger system must maintain high trigger efficiencies for the physics we are most interested in while suppressing the enormous QCD backgrounds. This requires massive computing power to minimize the online execution time of complex algorithms. A multi-level trigger is an effective solution to meet this challenge. The Fast Tracker (FTK) is an upgrade to the current ATLAS trigger system that will operate at full Level-1 output rates and provide high-quality tracks reconstructed over the entire inner detector by the start of processing in the Level-2 Trigger. FTK solves the combinatorial challenge inherent to tracking by exploiting the massive parallelism of associative memories that can compare inner detector hits to millions of pre-calculated patterns simultaneously. The tracking problem within matched patterns is further simplified by using pre-computed linearized fitting constants and relying on fast DSPs in modern commercial FPGAs. Overall, FTK is able to compute the helix parameters for all tracks in an event and apply quality cuts in less than 100 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu{\hbox {s}}$</tex> </formula> . The system design is defined and the performance presented with respect to high transverse momentum (high- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$p_{\rm T}$</tex></formula> ) Level-2 objects: b jets, tau jets, and isolated leptons. We test FTK algorithms using the full ATLAS simulation with WH events up to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$3\times 10^{34}~{\hbox {cm}}^{2}{\hbox {s}}^{1}$</tex></formula> luminosity and compare the FTK results with the offline tracking capability. We present the architecture and the reconstruction performance for the mentioned high- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$p_{\rm T}$</tex></formula> Level-2 objects.

The TOTEM experiment has measured the charged-particle pseudorapidity density dNch/dη in pp collisions at for 5.3<|η|<6.4 in events with at least one charged particle with transverse momentum above 40 MeV/c in this pseudorapidity range. This extends the analogous measurement performed by the other LHC experiments to the previously unexplored forward η region. The measurement refers to more than 99% of non-diffractive processes and to single and double diffractive processes with diffractive masses above ∼3.4 GeV/c2, corresponding to about 95% of the total inelastic cross-section. The dNch/dη has been found to decrease with |η|, from 3.84 ± 0.01(stat) ± 0.37(syst) at |η|=5.375 to 2.38±0.01(stat)±0.21(syst) at |η|=6.375. Several MC generators have been compared to data; none of them has been found to fully describe the measurement.

The muon telescopes of the Extreme Energy Events (EEE) experiment are based on Multigap Resistive Plate Chambers (MRPC). The EEE network is composed, so far, of 53 telescopes, each made of three MRPC detectors; it is organized in clusters and single telescope stations distributed all over the Italian territory and installed in High Schools, covering an area larger than 3×105 km2. The study of Extensive Air Showers (EAS), that is one of the goal of the project, requires excellent performance in terms of time and spatial resolution, efficiency, tracking capability and long term stability. The data from two recent coordinated data taking periods, named Run 2 and Run 3, have been used to measure these quantities and the results are here reported, together with a comparison with expectations and with the results from a beam test performed in 2006 at CERN.

Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at √s = 7 TeV in special runs with the Roman Pot detectors placed as close to the outgoing beam as seven times the transverse beam size. The differential cross-section measurements are reported in the |t|-range of 0.36 to 2.5 GeV2. Extending the range of data to low t values from 0.02 to 0.33 GeV2, and utilizing the luminosity measurements of CMS, the total proton-proton cross section at √s = 7 TeV is measured to be (98.3 ±0.2stat ±2.8syst) mb.

The TOTEM Experiment is designed to measure the total proton-proton cross-section with the luminosity-independent method and to study elastic and diffractive pp scattering at the LHC. To achieve optimum forward coverage for charged particles emitted by the pp collisions in the interaction point IP5, two tracking telescopes, T1 and T2, are installed on each side of the IP in the pseudorapidity region 3.1 < = |eta | < = 6.5, and special movable beam-pipe insertions - called Roman Pots (RP) - are placed at distances of +- 147 m and +- 220 m from IP5. This article describes in detail the working of the TOTEM detector to produce physics results in the first three years of operation and data taking at the LHC.

This paper describes the design and the performance of the timing detector developed by the TOTEM Collaboration for the Roman Pots (RPs) to measure the Time-Of-Flight (TOF) of the protons produced in central diffractive interactions at the LHC . The measurement of the TOF of the protons allows the determination of the longitudinal position of the proton interaction vertex and its association with one of the vertices reconstructed by the CMS detectors. The TOF detector is based on single crystal Chemical Vapor Deposition (scCVD) diamond plates and is designed to measure the protons TOF with about 50 ps time precision. This upgrade to the TOTEM apparatus will be used in the LHC run 2 and will tag the central diffractive events up to an interaction pileup of about 1. A dedicated fast and low noise electronics for the signal amplification has been developed. The digitization of the diamond signal is performed by sampling the waveform. After introducing the physics studies that will most profit from the addition of these new detectors, we discuss in detail the optimization and the performance of the first TOF detector installed in the LHC in November 2015.

Timing detectors are a well established part of High Energy Physics experimental instrumentation. The choice of sensors with fast (less than 10 ns) and precise (better than 100 ps) signals is an essential part of the design of a timing detector, together with radiation resistance considerations. Single crystal diamond sensors are one of the most promising technologies in this field. In this paper, the main characteristics that make single diamond crystal sensors ideal for timing applications will be described and an introduction to the design of fast front-end electronics will be given. Finally, two examples of diamond timing detectors used in High Energy Physics, the START detector of HADES and the TOTEM/CMS timing detector, will be discussed.

The pseudorapidity density of charged particles dN $$_{ ch }$$ /d $$\eta $$ is measured by the TOTEM experiment in proton–proton collisions at $$\sqrt{s} = 8$$ TeV within the range $$3.9<\eta <4.7$$ and $$-6.95<\eta <-6.9$$ . Data were collected in a low intensity LHC run with collisions occurring at a distance of 11.25 m from the nominal interaction point. The data sample is expected to include 96–97 % of the inelastic proton–proton interactions. The measurement reported here considers charged particles with $$p_T>0$$ MeV/c, produced in inelastic interactions with at least one charged particle in $$-7<\eta <-6$$ or $$3.7<\eta <4.8$$ . The dN $$_{ ch }$$ /d $$\eta $$ has been found to decrease with $$|\eta |$$ , from 5.11 $$\pm $$ 0.73 at $$\eta =3.95$$ to 1.81 $$\pm $$ 0.56 at $$\eta =-$$ 6.925. Several Monte Carlo generators are compared to the data and are found to be within the systematic uncertainty of the measurement.

The Extreme Energy Events (EEE) experiment, a joint project of the Centro Fermi and INFN Italian national research institutes, has a dual purpose: a scientific research program for measurements of the cosmic rays flux at ground level and an intense outreach and educational program with an active contribution of students and teachers in the construction and operation of the detectors in High Schools. The network counts 60 tracking detectors, each made by three Multigap Resistive Plate Chambers (MRPC), operated so far with a gas mixture composed by 98% C2H2F4 and 2% SF6. Given its high Global Warming Potential (GWP), the collaboration, since few years, started a R&D on alternative mixtures environmentally sustainable. Latest results on a C3H2F4 + He eco-friendly mixture are here presented.

The Extreme Energy Events (EEE) Project was born to include scientific, outreach and educational purposes. It is designed to detect and study high energy cosmic rays through the detection of the extensive air shower’s muon component through an array of muon telescopes based on Multigap Resistive Plate Chambers (MRPC) GPS synchronized. The telescopes are organized in local clusters and single telescope stations distributed all over the Italian territory and installed mainly in high schools buildings. These unconventional working sites offer young students the opportunity to get in touch with the world of high energy physics research. Every year hundreds of students and teachers are involved in the activities. The EEE Collaboration regularly schedules on-line activities: monthly meetings, masterclasses and seminars. Activities focusing on the upgrade phase of the EEE Project have been carried out in the last two years, with enormous success and participation. This contribution will present a general overview of the EEE outreach activities and the future plan.

Measurements from particle timing detectors are often affected by the time walk effect caused by statistical fluctuations in the charge deposited by passing particles. The constant fraction discriminator (CFD) algorithm is frequently used to mitigate this effect both in test setups and in running experiments, such as the CMS-PPS system at the CERN’s LHC. The CFD is simple and effective but does not leverage all voltage samples in a time series. Its performance could be enhanced with deep neural networks, which are commonly used for time series analysis, including computing the particle arrival time. We evaluated various neural network architectures using data acquired at the test beam facility in the DESY-II synchrotron, where a precise MCP (MicroChannel Plate) detector was installed in addition to PPS diamond timing detectors. MCP measurements were used as a reference to train the networks and compare the results with the standard CFD method. Ultimately, we improved the timing precision by 8% to 23%, depending on the detector's readout channel. The best results were obtained using a UNet-based model, which outperformed classical convolutional networks and the multilayer perceptron.

Abstract The Extreme Energy Events (EEE) Collaboration is fully involved in an ecological transition. The use of the standard gas mixture, C 2 H 2 F 4 + SF 6 , has stopped in favor of an alternative green mixture based on C 3 H 2 F 4 with the addition of He or CO 2 . The choise of these new mixtures is motivated by the significant lower Global Warming Potential (GWP) to reduce the emission of gases potentially contributing to the greenhouse effect. The EEE experiment consists of 61 muon telescopes based on Multigap Resistive Plate Chambers (MRPCs), each telescope composed of 3 chambers filled with gas. Several EEE detectors are today completely fluxed with the new ecological mixture. This contribution will report recent results about the telescope performance obtained from studies with the eco-friendly alternative mixture carried out in the last years.

Precise knowledge of the beam optics at the LHC is crucial to fulfil the physics goals of the TOTEM experiment, where the kinematics of the scattered protons is reconstructed with the near-beam telescopes -- so-called Roman Pots (RP). Before being detected, the protons' trajectories are influenced by the magnetic fields of the accelerator lattice. Thus precise understanding of the proton transport is of key importance for the experiment. A novel method of optics evaluation is proposed which exploits kinematical distributions of elastically scattered protons observed in the RPs. Theoretical predictions, as well as Monte Carlo studies, show that the residual uncertainty of this optics estimation method is smaller than 0.25 percent.

In this paper the first study of the upward going events detected by the telescopes of the Extreme Energy Event (EEE) project is reported. The EEE project consists of a detector array of Multigap Resistive Plate Chambers located at selected sites on the Italian territory. During autumn 2014 the first coordinated data taking period took place and around one billion candidate tracks were collected. Among them, of particular interest is the sample of particles which cross the telescopes from below. The results obtained demonstrate that the EEE telescopes can distinguish the electrons produced as decay products of cosmic muons stopped in the ground, or in the last chamber of the telescopes themselves, confirming the excellent performance of the system for the investigation of intriguing cosmic phenomena.

Abstract The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton–proton scattering at $$\sqrt{s} = 8\,\mathrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>8</mml:mn> <mml:mspace /> <mml:mi>TeV</mml:mi> </mml:mrow> </mml:math> in the squared four-momentum transfer range $$0.2\,\mathrm{GeV^{2}}&lt; |t| &lt; 1.9\,\mathrm{GeV^{2}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>0.2</mml:mn> <mml:mspace /> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> <mml:mo>&lt;</mml:mo> <mml:mrow> <mml:mo>|</mml:mo> <mml:mi>t</mml:mi> <mml:mo>|</mml:mo> </mml:mrow> <mml:mo>&lt;</mml:mo> <mml:mn>1.9</mml:mn> <mml:mspace /> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> . This interval includes the structure with a diffractive minimum (“dip”) and a secondary maximum (“bump”) that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for $$\sqrt{s} = 8\,\mathrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>8</mml:mn> <mml:mspace /> <mml:mi>TeV</mml:mi> </mml:mrow> </mml:math> yields the positions, $$|t|_{\mathrm{dip}} = (0.521 \pm 0.007)\,\mathrm{GeV^2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mo>|</mml:mo> <mml:mi>t</mml:mi> <mml:mo>|</mml:mo> </mml:mrow> <mml:mi>dip</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>0.521</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.007</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mspace /> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> and $$|t|_{\mathrm{bump}} = (0.695 \pm 0.026)\,\mathrm{GeV^2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mo>|</mml:mo> <mml:mi>t</mml:mi> <mml:mo>|</mml:mo> </mml:mrow> <mml:mi>bump</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>0.695</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.026</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mspace /> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> , as well as the cross-section values, $$\left. {\mathrm{d}\sigma /\mathrm{d}t}\right| _{\mathrm{dip}} = (15.1 \pm 2.5)\,\mathrm{{\mu b/GeV^2}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mfenced> <mml:mrow> <mml:mi>d</mml:mi> <mml:mi>σ</mml:mi> <mml:mo>/</mml:mo> <mml:mi>d</mml:mi> <mml:mi>t</mml:mi> </mml:mrow> </mml:mfenced> <mml:mi>dip</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>15.1</mml:mn> <mml:mo>±</mml:mo> <mml:mn>2.5</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mspace /> <mml:mrow> <mml:mi>μ</mml:mi> <mml:mi>b</mml:mi> <mml:mo>/</mml:mo> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> and $$\left. {\mathrm{d}\sigma /\mathrm{d}t}\right| _{\mathrm{bump}} = (29.7 \pm 1.8)\,\mathrm{{\mu b/GeV^2}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mfenced> <mml:mrow> <mml:mi>d</mml:mi> <mml:mi>σ</mml:mi> <mml:mo>/</mml:mo> <mml:mi>d</mml:mi> <mml:mi>t</mml:mi> </mml:mrow> </mml:mfenced> <mml:mi>bump</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>29.7</mml:mn> <mml:mo>±</mml:mo> <mml:mn>1.8</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mspace /> <mml:mrow> <mml:mi>μ</mml:mi> <mml:mi>b</mml:mi> <mml:mo>/</mml:mo> <mml:msup> <mml:mi>GeV</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> , for the dip and the bump, respectively.

We describe an important advancement for the Associative Memory device (AM). The AM is a VLSI processor for pattern recognition based on Content Addressable Memory (CAM) architecture. The AM is optimized for on-line track finding in high-energy physics experiments. Pattern matching is carried out by finding track candidates in coarse resolution “roads”. A large AM bank stores all trajectories of interest, called “patterns”, for a given detector resolution. The AM extracts roads compatible with a given event during detector read-out. Two important variables characterize the quality of the AM bank: its “coverage” and the level of fake roads. The coverage, which describes the geometric efficiency of a bank, is defined as the fraction of tracks that match at least one pattern in the bank. Given a certain road size, the coverage of the bank can be increased just adding patterns to the bank, while the number of fakes unfortunately is roughly proportional to the number of patterns in the bank. Moreover, as the luminosity increases, the fake rate increases rapidly because of the increased silicon occupancy. To counter that, we must reduce the width of our roads. If we decrease the road width using the current technology, the system will become very large and extremely expensive. We propose an elegant solution to this problem: the “variable resolution patterns”. Each pattern and each detector layer within a pattern will be able to use the optimal width, but we will use a “don't care” feature (inspired from ternary CAMs) to increase the width when that is more appropriate. In other words we can use patterns of variable shape. As a result we reduce the number of fake roads, while keeping the efficiency high and avoiding excessive bank size due to the reduced width. We describe the idea, the implementation in the new AM design and the implementation of the algorithm in the simulation. Finally we show the effectiveness of the “variable resolution patterns” idea using simulated high occupancy events in the ATLAS detector.

The Extreme Energy Events Project has been designed to join the scientific interest of a cosmic rays physics experiment with the enormous didactic potentiality deriving from letting it be carried out by high school students and teachers. After the initial phase, the experiment is starting to take data continuously, and the first interesting physics results have been obtained, demonstrating the validity of the idea of running a real physics investigation in these peculiar conditions. Here an overview of its structure and status is presented, together with some studies about detector performance and first physics results.

We propose a new generation of VLSI processors for pattern recognition, based on associative memory architecture, optimized for online track finding in high-energy physics experiments.We describe the architecture, the technology studies and the prototype design of a new associative memory project: it maximizes the pattern density on the ASIC, minimizes the power consumption and improves the functionality for the fast tracker processor proposed to upgrade the ATLAS trigger at LHC. I. INTRODUCTIONT HE track reconstruction in high-energy physics experi- ments requires large online computing power.The Fast Tracker for ATLAS triggers [1] is an evolution of the Silicon Vertex Tracker (SVT) in CDF [2], [3].The Fast Tracker is an online processor that tackles and solves the full track reconstruction problem at a hadron collider.The SVT track fitting system approaches the offline tracking precision with a processing time of the order of tens of microseconds, compatible with 30 kHz input event rates.This task is performed with negligible time delay by a Content Addressable Memory (CAM), also called Associative Memory (AM), i.e., a device that compares the event hits in parallel with all the stored pre-calculated low resolution track candidates (patterns), and returns the addresses of the matching patterns.A second processor receives the matching patterns and their related full-resolution hits to perform the final track fitting (Track Fitter, TF).A critical figure of merit for the AM-based track reconstruction system is the number of patterns that can be stored in the bank.For the SVT upgrade [2], [4], we developed a version of the AM chip (AMchip03) [5], using a 180 nm

This paper describes the performance of a prototype timing detector, based on 50 μm thick Ultra Fast Silicon Detector, as measured in a beam test using a 180 GeV/c momentum pion beam. The dependence of the time precision on the pixel capacitance and bias voltage is investigated in this paper. A timing precision from 30 ps to 100 ps (RMS), depending on the pixel capacitance, has been measured at a bias voltage of 180 V.

The Extreme Energy Events (EEE) Project is devoted to the study of Extensive Atmospheric Showers through a network of muon telescopes, installed in High Schools, with the further aim of introducing young students to particle and astroparticle physics. Each telescope is a tracking detector composed of three Multi-gap Resistive Plate Chambers (MRPC) with an active area of 1.60 × 0.80 m2. Their characteristics are similar to the ones built for the Time Of Flight array of the ALICE Experimentat LHC . The EEE Project started with a few pilot towns, where the telescopes have been taking data since 2008, and it has been constantly extended, reaching at present more than 50 MRPCs telescopes. They are spread across Italy with two additional stations at CERN, covering an area of around 3 × 105 km2, with a total surface area for all the MRPCs of 190 m2. A comprehensive description of the MRPCs network is reported here: efficiency, time and spatial resolution measured using cosmic rays hitting the telescopes. The most recent results on the detector and physics performance from a series of coordinated data acquisition periods are also presented.

Abstract The eruption of the Hunga-Tonga volcano in the South Pacific Ocean on January 15, 2022, at about 4:15 UTC, generated a violent explosion, which created atmospheric pressure disturbances in the form of Rayleigh-Lamb waves detected all over the globe. Here we discuss the observation of the Hunga-Tonga shock-wave performed at the Ny-Ålesund Research Station on the Spitsbergen island, by the detectors of the PolarquEEEst experiment and their ancillary sensors. Online pressure data as well as the results of dedicated offline analysis are presented and discussed in details. Results include wave arrival times, wave amplitude measurements and wave velocity calculation. We observed five passages of the shock wave with a significance larger than 3 $$\sigma$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>σ</mml:mi> </mml:math> and an amplitude up to 1 hPa. The average propagation velocity resulted to be (308 ± 0.6) m/s. Possible effects of the atmospheric pressure variation associated with the shock-wave multiple passages on the cosmic-ray rate at ground level are also investigated. We did not find any significant evidence of this effect.

The CMS Precision Proton Spectrometer (PPS), operating at the LHC, makes use of timing detectors based on planar single crystal CVD diamonds to measure the time of arrival of protons scattered in the very forward region. The time information is used to reconstruct the longitudinal position of the proton interaction vertex and to suppress pile-up background. The timing system, used during the LHC Run 2, has been upgraded for the Run 3, with the goal of reaching an ultimate timing resolution of better than 30 ps for protons in the TeV energy range. Here an overview of the PPS timing system is provided and the detector performance in Run 2 are briefly reported. The Run 3 upgrade will be outlined.

The need for reducing the emission of gases, potentially contributing to the greenhouse effect and climate change, has impacted many fields, including scientific research. The Extreme Energy Event (EEE) collaboration started, already several years ago, a series of tests aiming at finding a more eco-friendly replacement for the gases used in the Multigap Resistive Plate Chambers (MRPCs) of its network. These tests identified a promising binary gas mixture, and data taking has begun with a subset of the telescopes of the EEE network, making EEE the first experiment in the world completely implemented with MRPCs and operating with an eco-friendly gas mixture. Here the results of the tests and a preliminary comparison of the telescope performance measured with the standard (non eco-friendly) and the new eco-friendly gas mixtures are presented and discussed.

The Schwarzschild–Couder Telescope (SCT) is a dual mirror medium-sized telescope proposed for the Cherenkov Telescope Array (CTA), the next-generation very-high energy (from about 20 GeV to 300 TeV) gamma-ray observatory. The SCT design consists of a dual-mirror optics and a high resolution camera with a field of view (FoV) of 8 degrees squared, which will allow exceptional performance in terms of angular resolution and background rejection. A prototype telescope (named pSCT) has been installed at the Fred Lawrence Whipple Observatory in Arizona, USA. Its camera is partially equipped and covers a FoV of 2.7°. The pSCT has recently successfully detected the Crab Nebula with a statistical significance of 8.6 standard deviations. The upgrade of the pSCT focal plane is now ongoing, aimed to equip the full camera with upgraded sensors and electronics, enhancing the telescope field of view from the current 2.7°to the final 8°. In this presentation, an overview of the pSCT project and obtained results will be given, together with the camera upgrade status and expected performance.

The Extreme Energy Events (EEE) Project is a Centro Fermi - CERN - INFN - MIUR Collaboration Project for the study of extremely high energy cosmic rays, which exploits the Multigap Resistive Plate Chamber (MRPC) technology. The excellent time resolution and good tracking capability of this kind of detector allows us to study Extensive Air Showers (EAS) with an array of MRPC telescopes distributed across the Italian territory. Each telescope is installed in a high school, with the further goal to introduce students to particle and astroparticle Physics. The status of the experiment and the results obtained are reported.

The Extreme Energy Events project (EEE) is aimed to study Extensive Air Showers (EAS) from primary cosmic rays of more than 1018 eV energy detecting the ground secondary muon component using an array of telescopes with high spatial and time resolution. The second goal of the EEE project is to involve High School teachers and students in this advanced research work and to initiate them in scientific culture: to reach both purposes the telescopes are located inside High School buildings and the detector construction, assembling and monitoring - together with data taking and analysis - are done by researchers from scientific institutions in close collaboration with them. At present there are 42 telescopes in just as many High Schools scattered all over Italy, islands included, plus two at CERN and three in INFN units. We report here some preliminary physics results from the first two common data taking periods together with the outreach impact of the project.

The Extreme Energy Events (EEE) Project is meant to be the most extensive experiment to detect secondary cosmic particles in Italy. To this aim, more than 50 telescopes have been built at CERN and installed in high schools distributed all over the Italian territory. Each EEE telescope comprises three large area Multigap Resistive Plate Chambers (MRPCs) and is capable of reconstructing the trajectories of the charged particles traversing it with a good angular resolution. The excellent performance of the EEE telescopes allows a large variety of studies, from measuring the local muon flux in a single telescope, to detecting extensive air showers producing time correlations in the same metropolitan area, to searching for large-scale correlations between showers detected in telescopes tens, hundreds or thousands of kilometers apart. In addition to its scientific goal, the EEE Project also has an educational and outreach objective, its aim being to motivate young people by involving them directly in a real experiment. High school students and teachers are involved in the construction, testing and start-up of the EEE telescope in their school, then in its maintenance and data-acquisition, and later in the analysis of the data. During the last couple of years a great boost has been given to the EEE Project through the organization of simultaneous and centralized data taking with the whole telescope array. The raw data from all telescopes are transferred to CNAF (Bologna), where they are reconstructed and stored. The data are currently being analyzed, looking at various topics: variation of the rate of cosmic muons with time, upward going muons, muon lifetime, search for anisotropies in the muon angular distribution and for time coincidences between stations. In this paper an overall description of the experiment is given, including the design, construction and performance of the telescopes. The operation of the whole array is also presented by showing the most recent physics results.

A search for exclusive two-photon production via photon exchange in proton-proton collisions, pp $\to$ p$γγ$p with intact protons, is presented. The data correspond to an integrated luminosity of 9.4 fb$^{-1}$ collected in 2016 using the CMS and TOTEM detectors at a center-of-mass energy of 13 TeV at the LHC. Events are selected with a diphoton invariant mass above 350 GeV and with both protons intact in the final state, to reduce backgrounds from strong interactions. The events of interest are those where the invariant mass and rapidity calculated from the momentum losses of the forward-moving protons matches the mass and rapidity of the central, two-photon system. No events are found that satisfy this condition. Interpreting this result in an effective dimension-8 extension of the standard model, the first limits are set on the two anomalous four-photon coupling parameters. If the other parameter is constrained to its standard model value, the limits at 95% CL are $\lvertζ_1\rvert$ $\lt$ 2.9 $\times$ 10$^{-13}$ GeV$^{-4}$ and $\lvertζ_2\rvert$ $\lt$ 6.0 $\times$ 10$^{-13}$ GeV$^{-4}$.

The EEE (Extreme Energy Events) Project is an experiment for the detection of cosmic ray muons by means of a sparse array of telescopes, each made of three Multigap Resistive Plate Chambers (MRPC), distributed over all the Italian territory and at CERN. The main scientific goals of the Project are the investigation of the properties of the local muon flux, the detection of Extensive Air Showers (EAS) and the search for long-distance correlations between far telescopes. The Project is also characterized by a strong educational and outreach aspect since the telescopes are managed by teams of students and teachers who had previously constructed them at CERN. In this paper an overall description of the experiment is given, including the design, construction and performance of the telescopes. The operation of the whole array, which currently consists of more than 50 telescopes, is also presented by showing the most recent physics results.

The TOTEM collaboration has measured the proton-proton total cross section at $\sqrt{s}=13$ TeV with a luminosity-independent method. Using dedicated $β^{*}=90$ m beam optics, the Roman Pots were inserted very close to the beam. The inelastic scattering rate has been measured by the T1 and T2 telescopes during the same LHC fill. After applying the optical theorem the total proton-proton cross section is $σ_{\rm tot}=(110.6 \pm 3.4$) mb, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: $σ_{\rm el} = (31.0 \pm 1.7)$ mb and $σ_{\rm inel} = (79.5 \pm 1.8)$ mb.

This paper discusses the possibility to employ the Multi-gap Resistive Plate Chambers (MRPC) of the Extreme Energy Events (EEE) Project as muon tracking detectors to monitor the long term stability of civil buildings and structures when used in conjunction with additional detectors, to reconstruct the average direction of the cosmic muon tracks passing through both devices and any small variation over long time acquisition periods. The performance of such setup is discussed and preliminary experimental coincidence results obtained with a 40× 60 cm 2 scintillator detector operated in the same building with one of the EEE telescopes, at about 15 m vertical distance from it, are presented. Simple Monte Carlo and GEANT simulations were also carried out to evaluate typical acceptance values for the operating conditions employed so far, to extrapolate to other geometrical configurations, and to evaluate multiple scattering effects.

In order to improve the time precision of detectors based on diamonds sensors we have built a detector with two scCVD layers connected in parallel to the same amplifier. This work describes the design and the first measurements of such a prototype performed on a particle beam at CERN. With this different configuration we have obtained an improvement larger than a factor of 1.6–1.7 for the timing precision of the measurement when compared to a one layer scCVD diamond detector.

The Extreme Energy Events (EEE) Project employs Multi-gap Resistive Plate Chambers (MRPCs) for studying the secondary cosmic ray muons in Extensive Air Showers. The array consists of about 60 tracking detectors, sparse on Italian territory and at CERN. The MRPCs are flowed with a gas mixture based on C2H2F4 and SF6, both of which are fluorinated greenhouse gases with a high environmental impact on the atmosphere. Due to the restrictions imposed by the European Union, these gases are being phased out of production and their cost is largely increasing. The EEE Collaboration started a campaign to reduce the gas emission from its array with the aim of containing costs and decreasing the experiment global warming impact. One method is to reduce the gas rate in each EEE detector. Another is to develop a gas recirculation system, whose prototype has been installed at one of the EEE stations located at CERN. Jointly a parallel strategy is focused on searching for environmental friendly gas mixtures which are able to substitute the standard mixture without affecting the MRPC performance. An overview and the first results are presented here.

The Extreme Energy Events Project is an experiment devoted to the study of the Extensive Atmospheric Showers (EAS) which consists of a network of Multigap Resistive Plate Chambers (MRPCs) muon telescopes distributed over a very large area ∼3times105km2. It requires a precise time synchronization to correlate the information collected from each single detector. The data acquisition system of each telescope is equipped with a trigger unit and a GPS receiver to perform precision timing of events. The Global Positioning System (GPS) unit provides the one pulse per second signal (1PPS) which is used to create a timestamp in UTC time. A novel VME trigger unit for the EEE telescopes was developed, including an embedded GPS engine for timing application. The trigger/GPS unit is presented, including some preliminary measurements of its time resolution.

The TOTEM experiment at the LHC has performed the first measurement at $\sqrt{s} = 13$ TeV of the $\rho$ parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at $t=0$, obtaining the following results: $\rho = 0.09 \pm 0.01$ and $\rho = 0.10 \pm 0.01$, depending on different physics assumptions and mathematical modelling. The unprecedented precision of the $\rho$ measurement, combined with the TOTEM total cross-section measurements in an energy range larger than 10 TeV (from 2.76 to 13 TeV), has implied the exclusion of all the models classified and published by COMPETE. The $\rho$ results obtained by TOTEM are compatible with the predictions, from alternative theoretical models both in the Regge-like framework and in the QCD framework, of a colourless 3-gluon bound state exchange in the $t$-channel of the proton-proton elastic scattering. On the contrary, if shown that the 3-gluon bound state $t$-channel exchange is not of importance for the description of elastic scattering, the $\rho$ value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-$|t|$ reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton-proton cross-section measurement $\sigma_{tot} = 110.3 \pm 3.5$ mb, completely independent from the previous TOTEM determination. Combining the two TOTEM results yields $\sigma_{tot} = 110.5 \pm 2.4$ mb.

The Extreme Energy Events (EEE) experiment is the largest system in the world completely implemented with Multigap Resistive Plate Chambers (MRPCs). Presently, it consists of a network of 59 muon telescopes, each made of 3 MRPCs, devoted to the study of secondary cosmic rays. Its stations, sometimes hundreds of kilometers apart, are synchronized at a few nanoseconds level via a clock signal delivered by the Global Positioning System. The data collected during centrally coordinated runs are sent to INFN CNAF, the largest center for scientific computing in Italy, where they are reconstructed and made available for analysis. Thanks to the on-line monitoring and data transmission, EEE operates as a single coordinated system spread over an area of about 3 × 105 km2. In 2017, the EEE collaboration started an important upgrade program, aiming to extend the network with 20 additional stations, with the option to have more in the future. This implies the construction, testing and commissioning of 60 chambers, for a total detector surface of around 80 m2. In this paper, aspects related to this challenging endeavor are covered, starting from the technological solutions chosen to build these state-of-the-art detectors, to the quality controls and the performance tests carried on.

The Extreme Energy Events observatory is an extended muon telescope array, covering more than 10 degrees both in latitude and longitude. Its 59 muon telescopes are equipped with tracking detectors based on Multigap Resistive Plate Chamber technology with time resolution of the order of a few hundred picoseconds. The recent restrictions on greenhouse gases demand studies for new gas mixtures in compliance with the relative requirements. Tetrafluoropropene is one of the candidates for tetrafluoroethane substitution, since it is characterized by a Global Warming Power around 300 times lower than the gas mixtures used up to now. Several mixtures have been tested, measuring efficiency curves, charge distributions, streamer fractions and time resolutions. Results are presented for the whole set of mixtures and operating conditions, %. A set of tests on a real EEE telescope, with cosmic muons, are being performed at the CERN-01 EEE telescope. The tests are focusing on identifying a mixture with good performance at the low rates typical of an EEE telescope.

As the LHC luminosity is ramped up to 3×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">34</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and beyond, the high rates, multiplicities, and energies of particles seen by the detectors will pose a unique challenge. Only a tiny fraction of the produced collisions can be stored on tape and immense real-time data reduction is needed. An effective trigger system must maintain high trigger efficiencies for the physics we are most interested in, and at the same time suppress the enormous QCD backgrounds. This requires massive computing power to minimize the online execution time of complex algorithms. A multi-level trigger is an effective solution for an otherwise impossible problem. The Fast Tracker (FTK) is a proposed upgrade to the current ATLAS trigger system that will operate at full Level-1 output rates and provide high quality tracks reconstructed over the entire detector by the start of processing in Level-2. FTK solves the combinatorial challenge inherent to tracking by exploiting massive parallelism of associative memories that can compare inner detector hits to millions of pre-calculated patterns simultaneously. The tracking problem within matched patterns is further simplified by using pre-computed linearized fitting constants and leveraging fast DSPs in modern commercial FPGAs. Overall, FTK is able to compute the helix parameters for all tracks in an event and apply quality cuts in less than 100 μs. The system design is defined and studied with respect to high transverse momentum (high-P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) Level-2 objects: b-jets, tau-jets, and isolated leptons. We test FTK algorithms using ATLAS full simulation with WH events up to 3×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">34</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> luminosity and comparing FTK results with the offline tracking capability. We present the architecture and the reconstruction performances for the mentioned high-P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> Level-2 objects.

The Extreme Energy Events (EEE) Project is a Centro Fermi - CERN - INFN - MIUR Collaboration Project, for the study of extremely high-energy cosmic rays, which exploits the Multigap Resistive Plate Chamber (MRPC) technology. The excellent time resolution and good tracking capability of this detector allows us to study Extensive Air Showers (EAS) with an array of telescopes distributed all over the Italian territory. Each telescope is installed in a High School, with the additional goal to introduce students to particle and astroparticle Physics. The EEE array is composed, so far, of 47 telescopes, each made of three MRPC planes, spanning more than 10 degrees in latitude and 11 in longitude, organized in clusters and single telescope stations. The status of the experiment and the results, obtained during two recent coordinated data taking periods, will be reported. The observation of Forbush decreases, coincidence events among different telescopes and the muon decay, using more than 5 billion tracks collected in the last few months, are of particular interest.

The muon telescopes of the Extreme Energy Events (EEE) Project [1] are made of three Multigap Resistive Plate Chambers (MRPC). The EEE array is composed, so far, of 59 telescopes and is organized in clusters and single telescope stations distributed all over the Italian territory. They are installed in High Schools with the aim to join research and teaching activities, by involving researchers, teachers and students in the construction, maintenance, data taking and data analysis. The unconventional working sites, mainly school buildings with non-controlled environmental parameters and heterogeneous maintenance conditions, are a unique test field for checking the robustness, the low-ageing features and the long-lasting performance of the MRPC technology for particle tracking and timing purposes. The measurements performed with the EEE array require excellent performance in terms of time and spatial resolution, efficiency, tracking capability and stability. The data from two recent coordinated data taking periods, named Run 2 and Run 3, have been used to measure these quantities and the results are described, together with a comparison with expectations and with the results from a beam test performed in 2006 at CERN.

Central exclusive processes can be studied in CMS by combining the information of the central detector with the Precision Proton Spectrometer (PPS). PPS detectors, placed symmetrically at more than 200 m from the interaction point, can detect the scattered protons that survive the interaction. PPS has taken data at high luminosity while fully integrated in the CMS experiment. The total amount of collected data corresponds to more than 100 fb$^{-1}$ during the LHC Run 2. PPS consists of 3D silicon tracking stations as well as timing detectors that measure both the position and direction of protons and their time-of-flight with high precision. The detectors are hosted in special movable vacuum chambers, the Roman Pots, which are placed in the primary vacuum of the LHC beam pipe. The sensors reach a distance of few mm from the beam. Detectors have to operate in vacuum and must be able to sustain highly non-uniform irradiation: sensors used in Run 2 have accumulated an integrated dose with a local peak of $\sim 5 \cdot 10^{15}$ protons/cm$^2$. The timing system is made with high purity scCVD diamond sensors. A new architecture with two diamond crystals read out in parallel by the same electronic channel has been used to enhance the detector performance. In this paper, after a general overview of the PPS detector, we describe the timing system in detail. The sensor and the dedicated amplification chain are described, together with the signal digitization technique. Performance of the detector in Run 2 is reported. Recently the sensors used in Run 2 have been tested for efficiency and timing performance in a dedicated test beam at DESY. Preliminary results on radiation damage are reported. Important upgrades of the timing system are ongoing for the LHC Run 3, with the goal of reaching an ultimate timing resolution better than 30 ps; they are also discussed here.

Abstract The PolarquEEEst scientific programme consists in a series of measurements of the cosmic ray flux up to the highest latitudes. It started in Summer 2018, when three telescopes made out of scintillators readout by SiPMs were built and installed in Italy, Norway and on a sailboat leaving from North Island, to circumnavigate the Svalbard archipelago and land in Tromsø. They collected data on a latitude range from 44° N up to 82° N, with a dense sampling of the Northernmost interval. The PolarquEEEst mission continued afterwards with a series of measurements in Italy, Southward reaching Lampedusa, and in Germany. In May 2019 the PolarquEEEst collaboration accomplished another important result, installing a cosmic ray observatory for the detection of secondary cosmic muons at Ny Alesund, at 79° N, made of three independent identical detectors positioned a few hundred meters from each other, and synchronized in order to operate together as a network. The configuration used will allow high precision measurements never performed before at these latitudes on a long term, also interesting for their connection with environmental phenomena. The network will also complement the existing stations for the detection of cosmic neutrons at the Svalbard archipelago, enlarging by far the physics scope that is possible to pursue in this field at this peculiar location. Here the various missions are presented, and some preliminary results from the measurements performed are shown.

Abstract The goal of the PolarquEEEst experiment was to measure the cosmic charged particle rate at latitudes greater than 66 $$^{\circ }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow /><mml:mo>∘</mml:mo></mml:msup></mml:math> N, where no systematic and accurate measurements at sea level have ever been performed. A latitude range well above the Arctic Circle was explored on board of a sailboat, up to the unprecedented northernmost value of $$82^{\circ }07^{\prime }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mn>82</mml:mn><mml:mo>∘</mml:mo></mml:msup><mml:msup><mml:mn>07</mml:mn><mml:mo>′</mml:mo></mml:msup></mml:mrow></mml:math> N. In this paper a description of the experimental set-up is reported, then the procedures for calibration and data analysis are described in detail. The results show that the rate measured in this latitude range stays constant within a novel accuracy of $$\pm 1$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>±</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:math> %.

The TOTEM experiment is dedicated to the measurement of the total proton–proton cross-section with the luminosity-independent method and the study of elastic and diffractive scattering processes. Two tracking telescopes, T1 and T2, integrated in the CMS detector, cover the pseudo-rapidity region between 3.1 and 6.5 on both sides of the interaction point IP5. The Roman Pot (RP) stations are located at distances of ±147 m and ±220 m with respect to the interaction point to measure the very forward scattered protons at very small angles. During the LHC technical stop in winter 2010/2011, the TOTEM experiment was completed with the installation of the T1 telescope and the RP stations at ±147 m. In 2011, the LHC machine provided special optics with the large ß⁎=90 m, allowing TOTEM to measure the elastic scattering differential cross-section, down to the four-momentum transfer squared |t|=2×10−2 GeV2. Using the optical theorem and extrapolation of the differential cross-section to t=0 (optical point), the total p–p cross-section at the LHC energy of s=7TeV could be computed for the first time. Furthermore we measured with standard LHC beam optics and the energy of s=7TeV the forward charged particle pseudorapidity density dn/dη in the range of 5.3<|η|<6.4. The status of the experiment, the performance of the detectors with emphasis on the RPs are described and the first physics results are presented.

The Extreme Energy Events (EEE) ‘telescope’ is made by 3 Multigap Resistive Plate Chambers (MRPC), each with an active area of 158x82 cm2 in size. Each detector is part of a large network of about sixty telescopes spread over the Italian territory. Due to the good tracking capabilities (100 ps time resolution and cm2 spatial resolution) the EEE telescope can be used also as test station for large area detectors. The link between the EEE track and signals from the detector under test can be obtained by implementing a streaming DAQ with a common time reference between the two systems given by the GPS signal. The installation and first results of the cosmic muon test facility with the EEE MRPC telescope based on the low-cost, streaming-compatible 12 channels, 250MHz, 14 bits digitizer (INFN-WaveBoard or WB) developed by the JLAB12 Collaboration, is presented.

Abstract After its successful campaign of measurements beyond the Polar Arctic Circle, the PolarquEEEst experiment measured the cosmic charged particle rate at sea level in a latitude interval between 35 $$^{\circ }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow /> <mml:mo>∘</mml:mo> </mml:msup> </mml:math> N and 82 $$^{\circ }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow /> <mml:mo>∘</mml:mo> </mml:msup> </mml:math> N. In this paper, these measurements are described and the corresponding results are discussed.

Using two plastic scintillator tiles of 12.5 cm x 12.5 cm x 2 cm, we have developed a backpack-size portable cosmic rays detector controlled by a FPGA-based Arduino compatible board.The trigger is selectable between the AND and the OR functions between the two available tiles.In addition to the particle counts, the instrument can measure the time between two consecutive triggers to obtain distributions of the intervals of particle time of arrivals with two timescales, one of them compatible with the muon-decay analysis.Collected data, as well as the instrument configuration, are stored on a non-volatile memory.The collected data can be downloaded at any moment for further analysis.The instrument can be powered through the available USB port by a power bank to allow portable operations.A sound when a cosmic ray passes through the scintillators is generated by the controller that drives also a small LED display to see in real time trigger and tile signals.If necessary, a larger LED display can be connected.Data and status are shown by a LCD display and all can be controlled by three pushbuttons on the front panel.An open version of the instrument can accept up to four scintillators and is used to introduce the basic concepts of coincidence, acceptance, rate, randomness of the events, and allows the students to operate manually themselves the detectors.Additional, analogue output of the signals is available for further didactic purposes.A dedicated PC app can remotely control the instrument for an improved interaction with it.

The Extreme Energy Events (EEE) Collaboration is fully involved in an ecological transition. The use of the standard gas mixture, \ce{C_{2}H_{2}F_{4}}+ \ce{SF_{6}}, has stopped in favor of an alternative green mixture based on \ce{C_{3}H_{2}F_{4}} with the addition of He or \ce{CO_{2}}. The choise of these new mixtures is motivated by the significant lower Global Warming Potential (GWP) to reduce the emission of gases potentially contributing to the greenhouse effect. The EEE experiment consists of 61 muon telescopes based on Multigap Resistive Plate Chambers (MRPCs), each telescope composed of 3 chambers filled with gas. Several EEE detectors are today completely fluxed with the new ecological mixture. This contribution will report recent results about the telescope performance obtained from studies with the eco-friendly alternative mixture carried out in the last years.

Measurements from particle timing detectors are often affected by the time walk effect caused by statistical fluctuations in the charge deposited by passing particles. The constant fraction discriminator (CFD) algorithm is frequently used to mitigate this effect both in test setups and in running experiments, such as the CMS-PPS system at the CERN's LHC. The CFD is simple and effective but does not leverage all voltage samples in a time series. Its performance could be enhanced with deep neural networks, which are commonly used for time series analysis, including computing the particle arrival time. We evaluated various neural network architectures using data acquired at the test beam facility in the DESY-II synchrotron, where a precise MCP (MicroChannel Plate) detector was installed in addition to PPS diamond timing detectors. MCP measurements were used as a reference to train the networks and compare the results with the standard CFD method. Ultimately, we improved the timing precision by 8% to 23%, depending on the detector's readout channel. The best results were obtained using a UNet-based model, which outperformed classical convolutional networks and the multilayer perceptron.

We propose a new generation of VLSI processor for pattern recognition based on Associative Memory architecture, optimized for on-line track finding in high-energy physics experiments. We describe the architecture, the technology studies and the prototype design of a new R&D Associative Memory project: it maximizes the pattern density on ASICs, minimizes the power consumption and improves the functionality for the Fast Tracker (FTK) proposed to upgrade the ATLAS trigger at LHC. Finally we will focus on possible future applications inside and outside High Physics Energy (HEP).

The new proton timing stations of the Totem experiment are based on UltraFast Silicon Detectors installed in Roman Pots at 220 m from the interaction point 5 at LHC. The sensors have shown in beam test a timing resolution in the range 30–100 ps, depending on the pixel size. The readout is performed through a fast sampler chip: the SAMPIC. The best timing resolution can indeed be obtained only by recording the full waveform of the detector signal. The challenges to integrate the chip and the detector in the Totem-CMS DAQ and control systems will be discussed, together with the solutions adopted. The system has been successfully operated in LHC during some commissioning runs and during the special run in July 2018.

The TOTEM experiment has developed a new timing detector to be used during a special LHC run.The new proton timing detector, based on Ultrafast Silicon Detectors, is installed in the TOTEM Roman Pots, at 220 meters from the interaction point 5 at LHC.The sensors are readout through a fast sampler chip: the SAMPIC.With a sampler, it is possible to record the detector waveforms so that sophisticated offline algorithms can be used to achieve the best timing performance.A new board has been designed to integrate the chip in the TOTEM and CMS DAQ and control systems.The core component of the board is a radiation hard FPGA, with a dedicated firmware designed to configure the SAMPIC and assemble the DAQ data frame event.The system was successfully operated during the run in July 2018.The detector will be described and the preliminary results discussed.

The existence of time correlations in detectors separated by distances much larger than the size of the highest energy extensive air showers (EAS) has been long discussed over the years. Several mechanisms have been proposed to justify the existence of such events and, in the last decade, some experiments have also tried to search for correlations on a large scale distance, beyond one hundred kilometers. The approaches were based on the construction of clusters of detectors placed at large relative distances, with the capability of selecting extensive air showers. Within this context, the Extreme Energy Events (EEE) experiment can provide new inputs in the search for long distance correlations, thanks to its sparse array of muon telescopes spanning all the Italian territory. The EEE telescopes are taking data since more than 10 years and enough statistics has been already accumulated to be able to search for such events, whose observation is intrinsically difficult due to the very low rates expected, many order of magnitudes smaller than the overall cosmic ray flux. In order to reduce the accidental correlations, different analysis approaches have been investigated for the selection of EAS events with the EEE telescopes. In this paper we will present preliminary results obtained by analyzing a large fraction of the statistics currently available.

Due to their penetration capability, cosmic muons may provide a way to monitor the alignment and possible long term deformations of large structures, such as historical or other civil buildings. The basic idea behind this possibility is to look for any misalignment between position-sensitive detectors, fixed to different parts of the structure, relative to the original alignment condition. In this paper we discuss the possibility of employing Multigap Resistive Plate Chambers (MRPC) as tracking devices, operating them in coincidence with additional detectors without tracking capability. One of the MRPC telescopes (size 158× 82 cm2) of the Extreme Energy Events (EEE) project, installed in the underground floor at the Department of Physics and Astronomy in Catania, was used together with a 40× 60 cm2 scintillator-based detector, located at about 16 m vertical distance, on the third floor of the same building. Coincidence measurements were carried out over a period of about two months by shifting the position of the smaller detector, to mimic the movement of the structure. Plans for future studies with different detectors and under different geometrical configurations are also discussed.

A search for long-lived particles (LLPs) produced in association with a Z boson is presented. The study is performed using data from proton-proton collisions with a center-of-mass energy of 13 TeV recorded by the CMS experiment during 2016-2018, corresponding to an integrated luminosity of 117 fb$^{-1}$. The LLPs are assumed to decay to a pair of standard model quarks that are identified as displaced jets within the CMS tracker system. Triggers and selections based on Z boson decays to electron or muon pairs improve the sensitivity to light LLPs (down to 15 GeV). This search provides sensitivity to beyond the standard model scenarios which predict LLPs produced in association with a Z boson. In particular, the results are interpreted in the context of exotic decays of the Higgs boson to a pair of scalar LLPs (H $\to$ SS). The Higgs boson decay branching fraction is constrained to values less than 6% for proper decay lengths of 10-100 mm and for LLP masses between 40 and 55 GeV. In the case of low-mass ($\approx$15 GeV) scalar particles that subsequently decay to a pair of b quarks, the search is sensitive to branching fractions $\mathcal{B}$(H $\to$ SS) $\lt$ 20% for proper decay lengths of 10-50 mm. The use of associated production with a Z boson increases the sensitivity to low-mass LLPs of this analysis with respect to gluon fusion searches. In the case of 15 GeV scalar LLPs, the improvement corresponds to a factor of 2 at a proper decay length of 30 mm.

A measurement of inclusive four-jet production in proton-proton collisions at a center-of-mass energy of 13\TeV is presented. The transverse momenta of jets within $\lvert\eta\rvert \lt$ 4.7 reach down to 35, 30, 25, and 20 GeV for the first-, second-, third-, and fourth-leading jet, respectively. Differential cross sections are measured as functions of the jet transverse momentum, jet pseudorapidity, and several other observables that describe the angular correlations between the jets. The measured distributions show sensitivity to different aspects of the underlying event, parton shower, and matrix element calculations. In particular, the interplay between angular correlations caused by parton shower and double-parton scattering contributions is shown to be important. The double-parton scattering contribution is extracted by means of a template fit to the data, using distributions for single-parton scattering obtained from Monte Carlo event generators and a double-parton scattering distribution constructed from inclusive single-jet events in data. The effective double-parton scattering cross section is calculated and discussed in view of previous measurements and of its dependence on the models used to describe the single-parton scattering background.

We describe the results and status of our R&D on diamond timing detectors for the TOTEM experiment at CERN. Tests with commercial devices have been done and here reported; the unsatisfactory results push us to design a new detector. We present test beams results and the front-end electronics, critical point of the design. Efficiency studies and timing performance dependence from detector capacitance will be also reported.

The whole Extreme Energy Events (EEE) array is composed of 61 telescopes installed in Italian High Schools, built and operated by students and teachers, constantly supervised by researchers. The muon telescope of the EEE Project is made by 3 Multigap Resistive Plate Chambers (MRPC). The unconventional working sites are a unique test field for checking the robustness and the low-ageing features of the MRPC technology for particle tracking and timing purposes. The MRPCs are fluxed with a standard mixture (98% C 2 H 2 F 4 - 2% SF 6 ) of greenhouse gases (GHG) phasing out of production. The EEE Collaboration is currently studying alternative mixtures environmentally and economically sustainable. The EEE Collaboration actions to reduce the Global Warming Potential (GWP) in the MRPC array of the EEE experiment are progressing.

The upcoming phase of expansion of the telescope network of the EEE project has recently inspired a proposal of redesign of the detector control and monitoring, as well as data acquisition interfaces. The new design results in a very compact and versatile system with a significant cost reduction. The system architecture is described, with emphasis on the integration of data acquisition, trigger and GPS into a single unit. Performances of a fully functional prototype are also reported, as well as plans for future developments.

The TOTEM experiment is dedicated to the measurement of the total proton-proton cross-section with the luminosity-independent method and the study of elastic and diffractive scattering processes. Two tracking telescopes, T1 and T2, integrated in the CMS detector, cover the pseudo-rapidity region between 3.1 and 6.5 on both sides of the interaction point IP5. The Roman Pot (RP) stations are located at distances of ± 147m and ± 220 m with respect to the interaction point to measure the very forward scattered protons at very small angles. During the LHC technical stop in winter 2010/2011, the TOTEM experiment was completed with the installation of the T1 telescope and the RP stations at ± 147 m. In 2011, the LHC machine provided special optics with the large ß* = 90 m, allowing TOTEM to measure the elastic scattering differential cross section, down to the four-momentum transfer squared |t| = 2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> GeV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Using the optical theorem and extrapolation of the differential cross section to t = 0 (optical point), the total p-p cross section at the LHC energy of √v = 7 TeV could be computed for the first time. The status of the experiment, the performance of the detectors with emphasis on the RPs are described and the first physics results are presented.

The pseudorapidity density of charged particles dN(ch)/deta is measured by the TOTEM experiment in pp collisions at sqrt(s) = 8 TeV within the range 3.9 &lt; eta &lt; 4.7 and -6.95 &lt; eta &lt; -6.9. Data were collected in a low intensity LHC run with collisions occurring at a distance of 11.25 m from the nominal interaction point. The data sample is expected to include 96-97\% of the inelastic proton-proton interactions. The measurement reported here considers charged particles with p_T &gt; 0 MeV/c, produced in inelastic interactions with at least one charged particle in -7 &lt; eta &lt; -6 or 3.7 &lt; eta &lt;4.8 . The dN(ch)/deta has been found to decrease with |eta|, from 5.11 +- 0.73 at eta = 3.95 to 1.81 +- 0.56 at eta= - 6.925. Several MC generators are compared to the data and are found to be within the systematic uncertainty of the measurement.

Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at $\sqrt{s} = 7 $ TeV in special runs with the Roman Pot detectors placed as close to the outgoing beam as seven times the transverse beam size. The differential cross-section measurements are reported in the |t|-range of 0.36 to 2.5 GeV^2. Extending the range of data to low t values from 0.02 to 0.33 GeV^2,and utilizing the luminosity measurements of CMS, the total proton-proton cross section at sqrt(s) = 7 TeV is measured to be (98.3 +- 0.2(stat) +- 2.8(syst)) mb.

In this paper, the description of a new activity started at INRIM Time Laboratory at the end of year 2019, is proposed. It is based on the on-going support provided to the Extreme Energy Events (EEE) Cosmic Rays Observatory, for the metrological characterization and optimization of its timing system. After briefly relating about the Cosmic Rays (CR) and Extensive Air Showers (EAS) phenomena, the description of the EEE Observatory will be provided, highlighting the importance of timing in the detection of EAS correlations. After entering in details of its role, the preliminary activities carried out by INRIM during the first months of collaboration with EEE will be addressed. Some general considerations, together with some future perspectives, will represent the conclusion of the paper.

Abstract Cosmic ray muons are a penetrating component of extensive air showers created in the Earth atmosphere by the interaction of highly energetic primary particles, mostly protons, which continuously bombard our Planet. The secondary cosmic radiation is the result of the complex interplay between the production cross section and the interaction mechanisms with the atmosphere (including the energy loss, multiple scattering and particle decay). Cosmic muons have been considered since several decades as a powerful probe to exploit our environment, from muography of volcanoes to absorption radiography of possible hidden rooms inside large structures, such as Pyramids, to the detection of high-Z illicit nuclear materials inside containers and many other applications of social interest. This paper discusses the possibility to employ the Multigap Resistive Plate Chambers (MRPC) of the Extreme Energy Events (EEE) Project as muon tracking detectors to monitor the long term stability of civil buildings and structures when used in conjunction with additional detectors. For this application the average direction of the cosmic muon tracks passing through the MRPC telescope and an additional detector located some distance apart in the same building may be reconstructed with good precision and any small variation over long time acquisition periods may be monitored. The performance of such setup is discussed and experimental results from first coincidence measurements obtained with a 40 × 60 cm 2 scintillator detector operated in the same building with one of the EEE telescopes, at about 15 m vertical distance from it, are presented. Simple Monte Carlo and GEANT simulations were also carried out to evaluate typical acceptance values for the operating conditions employed so far, to extrapolate to other geometrical configurations, and to evaluate multiple scattering effects.

Abstract A simulation tool based on GEMC framework to describe the MRPC telescope of the Extreme Energy Events (EEE) Project is presented. The EEE experiment is mainly devoted to the study of the secondary cosmic muons by using MRPC telescope distributed in high schools and research centres in Italy and at CERN. This takes into account the muon interactions with EEE telescopes and the structures surrounding the experimental apparata; it consists of a dedicated event generator producing realistic muon distribution and a detailed geometry description of the detector. Microscopic behaviour of MRPCs has been included to produce experimental-like data. A method to estimate the chamber efficiency directly from data has been implemented and tested by comparing the experimental and simulated polar angle distribution of muons.

Abstract Due to their efficiency, tracking capabilities and long-term operational conditions, Multigap Resistive Plate Chambers (MRPC) may be used in a stable location in coincidence with additional detectors fixed to other parts of a civil building, to detect relative displacements of different parts of the building due to long term deformations of the structure. In this contribution we report the results of two different measurements carried out in the Department of Physics and Astronomy of the University of Catania (with three floors above the ground and an underground basement), using one of the MRPC telescopes of the Extreme Energy Events project, in coincidence with two scintillator-based muon telescopes located in various positions inside the building. Experimental results obtained by these measurements campaigns over a period of about three months are reported, together with a discussion about the performance of the technique. The sensitivity of the method is also discussed by means of Monte Carlo simulations.

The existence of independent, yet time correlated, Extensive Air Showers (EAS) has been discussed over the past years, with emphasis on possible physical mechanisms that could justify their observation. The detector network of the Extreme Energy Events (EEE) Collaboration, with its approximately 60 cosmic ray telescopes deployed over the Italian territory, has the potential to search for such events, employing different analysis strategies. In this paper, we have analyzed a set of EEE data, corresponding to an approximately five month observation period, searching for multi-coincidence events among several far telescopes, within a time window of 1 ms. Events with up to 12 coincident telescopes have been observed. Results were compared to expectations from a random distribution of events and discussed with reference to the relativistic dust grain hypothesis.

The first physics results from the TOTEM experiment are here reported, concerning the measurements of the total, differential elastic, elastic and inelastic pp cross-section at the LHC energy of $\sqrt{s}$ = 7 TeV, obtained using the luminosity measurement from CMS. A preliminary measurement of the forward charged particle $\eta$ distribution is also shown.

TOTEM is an experiment designed to perform total cross section, elastic scattering, and diffractive dissociation measurements at the LHC. It is made up of elastic detectors set in the tunnel (Roman Pots) and two inelastic telescopes: T1 and T2, located in the same cavern as the CMS experiment. The T2 telescope is placed at the very forward region of the CMS's detector, in a high radioactive environment, as revealed by measurements performed using radiation sensors. The amount of particles produced in the interaction with material in front of and around the detector was found to be particularly challenging for both detector performances and physics analysis. The offline software developed for the reconstruction of inelastic events tracks is briefly described. Internal and general alignments of the telescopes have been another complex issue: the strategy to correct the misalignment biases are explained. A preliminary measurements of the forward charged particle η distribution performed by T2 is also presented.