N. Pastrone

Muon colliders offer enormous potential for the exploration of the particle physics frontier but are challenging to realize. A new international collaboration is forming to make such a muon collider a reality.

A muon collider represents the ideal machine to reach very high center-of-mass energies and luminosities by colliding elementary particles. This is the result of the low level of beamstrahlung and synchrotron radiation compared to linear or circular electron-positron colliders. In contrast with other lepton machines, the design of a detector for a multi-TeV muon collider requires detailed knowledge of the interaction region due to the significant backgrounds created by muon beam decays in the collider ring. The physics reach can be properly evaluated only when the detector performance in such an environment is determined. In this work, the backgrounds generated by muon beams of 750 GeV are characterized and the performance of the tracking system and the calorimeter detector is illustrated. Solutions to minimize the effect of the beam-induced backgrounds are discussed and applied to obtain track and jet reconstruction performance. The μ+μ−→ Hνν̄→ bb̄ νν̄ process is fully simulated and reconstructed to demonstrate that physics measurements are possible in this harsh environment. The measurement precision for the Higgs boson coupling to bb̄ is evaluated for √s=1.5, 3, and 10 TeV and compared to other proposed machines.

We have performed a search for the 1P1 state of charmonium resonantly formed in p¯p annihilations, close to the center of gravity of the 3PJ states. We report results from the study of the J/ψ+π0 and J/ψ+2π final states. We have observed a statistically significant enhancement in the p¯+p→J/ψ+π0 cross section at √s ≃3526.2 MeV. This enhancement has the characteristics of a narrow resonance of mass, total width, and production cross section consistent with what is expected for the 1P1 state. In our search we have found no candidates for the reactions p¯+p→J/ψ+π0+π0 and p¯+p→J/ψ+π++π−.Received 10 July 1992DOI:https://doi.org/10.1103/PhysRevLett.69.2337©1992 American Physical Society

Cross sections for the reaction pp\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ have been measured at s=8.9,12.4, and 13.0 ${\mathrm{GeV}}^{2}$. The cross sections have been analyzed to obtain the proton electromagnetic form factors in the timelike region. We find that ${\mathit{G}}_{\mathit{M}}$(${\mathit{q}}^{2}$)\ensuremath{\propto}${\mathit{q}}^{\mathrm{\ensuremath{-}}4}$${\mathrm{\ensuremath{\alpha}}}_{\mathit{s}}^{2}$(${\mathit{q}}^{2}$) for ${\mathit{q}}^{2}$\ensuremath{\ge}5 (GeV/c${)}^{2}$.

The cross section for the reaction $\overline{p}\stackrel{\ensuremath{\rightarrow}}{p}{e}^{+}{e}^{\ensuremath{-}}$ has been measured at $s=8.8,$ $10.8,$ $12.4,$ $13.1,$ and $14.4 {\mathrm{GeV}}^{2}$ by Fermilab experiment E835. A non-magnetic spectrometer is used to identify the ${e}^{+}{e}^{\ensuremath{-}}$ final states generated by the antiproton beam intersecting an internal hydrogen gas jet target. From the analysis of the 144 observed events, new high-precision measurements of the proton magnetic form factor for timelike momentum transfers are obtained.

This experiment has been performed at the CERN Intersecting Storage Rings to study the direct formation of charmonium states in antiproton-proton annihilations. The experimental program has partly been devoted to an inclusive scan for pp → J/ψ + X in the range 3520–3530 MeV/c2. A cluster of five events has been observed in a narrow energy band, centred on the centre of gravity of the 3PJ states where the 1P1 is expected to be. When interpreted as a new resonace, these data yield a mass m = 3525.4±0.8 MeV/c2.

Fermilab experiment E835 has measured the cross section for the reaction p̄p→e+e− at s=11.63, 12.43, 14.40 and 18.22 GeV2. From the analysis of the 66 observed events new high-precision measurements of the proton magnetic form factor are obtained.

We report on a study of the χ1(3P1) and χ2(3P2) states of charmonium formed in antiproton-proton annihilations. An energy scan through the resonances, performed with a very narrow momentum-band beam of antiprotons intersecting a hydrogen jet target, enables us to perform very precise measurements of the mass and the total width of the two resonances. From a sample of 513 χ1 and 585 χ2 events we find Mχ1 = (3510.53±0.13) MeV/c2, Mχ2 = (3556.15±0.14) MeV/c2, Γχ1 = (0.88±0.14) MeV and Γχ2 = (1.98±0.18) MeV. From our measurement of the quantity Γ(R → pp) × BR(R → Jψ → e+ e−), using known branching ratios, we obtain Λ(χ1 → pp) = (69±13) eV and Λ(χ2 → pp) = (180±31) eV.

We report evidence for the hc state of charmonium in its ηcγ decay mode and lack of evidence in the J/ψπ0 mode. We studied these channels in p¯p annihilations near the center of gravity of the PJ3 states, where the hc was reported in the J/ψπ0 mode by E760, our previous experiment, at 3526.2±0.15±0.2 MeV, with ΓR≤1 MeV. We observe an event excess in the ηcγ mode near 3526 MeV. Testing the null hypothesis of a linearly varying background cross section against the alternate hypothesis that includes a resonance near 3526 MeV, we reject the null hypothesis with P∼0.001. The resonance mass is 3525.8±0.2±0.2 MeV and the resonance width ≤1 MeV. We estimate 10.0±3.5<Γp¯pBηcγ<12.0±4.5 eV, corresponding to fixed values 0.5<ΓR<1.0 MeV. We find no event excess within the search region in the J/ψπ0 mode.4 MoreReceived 13 May 2005DOI:https://doi.org/10.1103/PhysRevD.72.032001©2005 American Physical Society

X-ray computed tomography (CT) is now used in the cultural heritage field because it is non-invasive and it can give a large amount of information on the inner structure of the object under study. Until recently mainly medical CT scanners or micro-CT setups have been used, limiting the analysis to relatively small artworks or requiring multiple acquisition and difficult image-joining for objects larger than detector dimensions. To overcome the limitations of ordinary CT devices, a facility for the X-ray tomography of large size artefacts has recently been designed and installed in a protected area of the Fondazione Centro Conservazione e Restauro "La Venaria Reale", a Centre for Preservation and Restoration. This facility, based on a X-ray source, a linear X-ray detector and a high precision mechanical system, has been and will be used to gather information on materials, manufacturing techniques and conservative conditions of artworks undergoing the restoration process. In this paper the results of the tomography of the first analyzed large artistic object are presented, giving an idea of the wealth of information obtained from the CT scan. The presented artwork is the writing cabinet called "doppio corpo", a masterpiece of furniture more than 3 m high, inlaid for Savoy Residences by Pietro Piffetti, the most famous cabinet-maker in Piedmont in the XVIII century. The artwork is now housed in the Quirinale Palace, the official residence of the Italian President in Rome. The CT analysis permitted us to obtain valuable information about the conservative conditions, the presence of previous interventions, the distribution of various materials and the dimensions and arrangement of several wooden pieces, thus allowing for interesting hypotheses about the building technique of this masterpiece.

The high-luminosity phase of operation of the CERN Large Hadron Collider (HL-LHC) will pose new challenges to the detectors and their readout electronics. In particular, the Compact Muon Solenoid (CMS) barrel electromagnetic calorimeter will require a full redesign of the electronic readout chain in order to cope with the increase in luminosity and trigger rate. In this framework, a new application-specific integrated circuit (ASIC) integrating A/D conversion, lossless data compression, and high-speed transmission has been developed and tested. The ASIC, named Lisboa-Torino Ecal Data Transmission Unit (LiTE-DTU), is designed in a commercial CMOS 65-nm process and embeds two 12-bit, 160-MS/s analog-to-digital converters (ADCs), a data selection and compression logic, and a 1.28-Gb/s output serial link. The high-speed 1.28-GHz clock is generated internally from the 160-MHz input by a clock multiplication phase-locked loop (PLL). The circuit has been designed implementing radiation-tolerant techniques in order to work in the harsh environment of the HL-LHC upgrade. The LiTE-DTU is currently in the preproduction phase. A sample of 600 chips has been tested and incorporated into front-end (FE) boards for systems performance testing.

We report new measurements for the mass, width, and branching ratios for the $\frac{J}{\ensuremath{\psi}}$ and the ${\ensuremath{\psi}}^{\ensuremath{'}}$. These charmonium states are formed exclusively in $\overline{p}p$ annihilations at the Fermilab Antiproton Accumulator ring, where stochastically cooled antiprotons are brought into collision with the protons of an internal hydrogen gas jet target. The antiproton energy is precisely controlled and measured allowing an accurate measurement of the resonance parameters. From the shape of the excitation curves we find that the widths of $\frac{J}{\ensuremath{\psi}}$ and ${\ensuremath{\psi}}^{\ensuremath{'}}$ are $\ensuremath{\Gamma}(\frac{J}{\ensuremath{\psi}})=99\ifmmode\pm\else\textpm\fi{}12\ifmmode\pm\else\textpm\fi{}6$ keV and $\ensuremath{\Gamma}({\ensuremath{\psi}}^{\ensuremath{'}})=306\ifmmode\pm\else\textpm\fi{}36\ifmmode\pm\else\textpm\fi{}16$ keV, and that the mass of the $\frac{J}{\ensuremath{\psi}}$ is 3096.87 \ifmmode\pm\else\textpm\fi{} 0.03 MeV/${\mathit{c}}^{2}$. For the $\frac{J}{\ensuremath{\psi}}$ we obtain $B(\frac{J}{\ensuremath{\psi}}\ensuremath{\rightarrow}\overline{p}p)B(\frac{J}{\ensuremath{\psi}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}})=({1.14}_{\ensuremath{-}0.12}^{+0.16}\ifmmode\pm\else\textpm\fi{}0.10)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$; for the ${\ensuremath{\psi}}^{\ensuremath{'}}$ we obtain $B({\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}\overline{p}p)[B({\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}})+B({\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}\frac{J}{\ensuremath{\psi}X})B(\frac{J}{\ensuremath{\psi}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}})]=({1.17}_{\ensuremath{-}0.12}^{+0.14}\ifmmode\pm\else\textpm\fi{}0.08)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$.

We present the first high-statistics study of the ηη system over the mass range 1000–3000 MeV/c2. The experiment was performed at the Fermilab Antiproton Accumulator, and the data sample consists of six-photon final states produced in antiproton-proton annihilations at s in the range 2950–3620 MeV. We find evidence for three states with masses 1488 ± 10 MeV/c2, 1748 ± 10 MeV/c2 and 2104 ± 20 MeV/c2 respectively.

In an experiment performed at the CERN-ISR the direct formation is observed of the χ1 and χ2 charmonium states in proton-antiproton annihiliation. A novel technique provided excellent energy resolution together with small background and reduced systematics. The following values for the masses and total widths of the states were obtained: Λχ1 <3 MeV (95% CL); mχ1 = (3511.3±0.4±0.4) MeV; Λχ2=(2.6 +1.4−1.0) MeV; mξ2=(3556.9±0.4±0.5) MeV. First measurements of the partial widths to antiproton-proton are also reported: Λ(χ1→pp)=57+13-11±11) and Λ(χ2→pp)=(233 +51-45±48) eV.

As part of the charmonium formation experiment at the CERN Intersecting Storage Rings, we studied the reaction pp→cc→γγ in an antiproton momentum scan through the ηc, χ1, and χ2 regions. We report events observed in the ηc and χ2 regions, whilst no event was observed in the χ1 region, as expected for a spin-1 state.

We report on a study of the angular distributions in the radiative decay of the χc1 and χc2 states formed in p¯p annihilations. These distributions depend on the dynamics of the formation process and the multipole structure of the radiative decay. Using 2090 χc1 and 5908 χc2 events, we have measured the fractional magnetic quadrupole amplitude to be a2(χc1)≃M2/E1=0.002±0.032, and a2(χc2)=−0.093−0.041+0.039. We have also measured the square of the helicity 0 fractional amplitude in the χc2 formation process to be B02=0.13±0.08. Received 3 July 2001DOI:https://doi.org/10.1103/PhysRevD.65.052002©2002 American Physical Society

Experiment R704, the last to be performed at the CERN-ISR, has successfully applied a new method to study (cc) states formed directly in antiproton-proton annihilations. The novelty of the method rests on the capability to build a highly performing annihilation source by letting a cold

The design of a future multi-TeV muon collider needs new ideas to overcome the technological challenges related to muon production, cooling, accumulation and acceleration. In this paper a layout of a positron driven muon source known as the Low EMittance Muon Accelerator (LEMMA) concept is presented. The positron beam, stored in a ring with high energy acceptance and low emittance, is extracted and driven to a multi-target system, to produce muon pairs at threshold. This solution alleviates the issues related to the power deposited and the integrated Peak Energy Density Deposition (PEDD) on the targets. Muons produced in the multi-target system will then be accumulated before acceleration and injection in the collider. A multi-target line lattice has been designed to cope with the focusing of both the positron and muon beams. Studies on the number, material and thickness of the targets have been carried out. A general layout of the overall scheme and a description is presented, as well as plans for future R&D.

Introduction: Charged Particle Therapy plays a key role in the treatment of deep-seated tumours, because of the advantageous energy deposition culminating in the Bragg peak. However, knowledge of the dose delivered in the entrance channel is limited by the lack of data on the beam and fragmentation of the target. Methods: The FOOT experiment has been designed to measure the cross sections of the nuclear fragmentation of projectile and target with two different detectors: an electronic setup for the identification of Z ≥ 3 fragments and a nuclear emulsion spectrometer for Z ≤ 3 fragments. In this paper, we analyze the data taken by exposing four nuclear emulsion spectrometers, with C and C 2 H 4 targets, to 200 MeV/n and 400 MeV/n oxygen beams at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany), and we report the charge identification of produced fragments based on the controlled fading induced on nuclear emulsion films. Results: The goal of identifying fragments as heavy as lithium has been achieved. Discussion: The results will contribute to a better understanding of the nuclear fragmentation process in charged particle therapy and have implications for refining treatment planning in the presence of deep-seated tumors.

Accurate measurements of physical processes in high energy frontier experiments demand exceptional spatial, temporal, and energy precision to discern the physics behind high-energy particle jets. Calorimeters, like other detection systems, must be able to meet these increasingly challenging performance requirements. In the prospective TeV-scale Muon Collider, the primary hurdle in designing detectors and devising event reconstruction algorithms is the challenge posed by Beam-Induced Background (BIB). Nevertheless, it is conceivable to mitigate the impact of BIB on the Muon Collider’s calorimeter by capitalizing on certain characteristics and ensuring key features such as high granularity, precise timing, longitudinal segmentation, and superior energy resolution. This is what the here described R&D is trying to achieve with an innovative semi-homogeneous electromagnetic calorimeter constructed from stackable and interchangeable modules composed of lead fluoride crystals (PbF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). These modules are equipped with surface-mount UV-extended Silicon Photomultipliers (SiPMs) and are collectively referred to as the Crilin calorimeter (CRystal calorImeter with Longitudinal INformation). The challenge lies in making sure this calorimeter can operate effectively within an extremely harsh radiation environment, enduring an annual neutron flux of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1MeV</sub> / <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cm</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a total ionizing dose of 10 kGy. In this paper, the radiation tolerance measured in several irradiation campaigns is discussed and the timing performances during a test beam at CERN-H2 with 120-GeV electrons. Additionally a description of the latest prototype, Proto-1, is provided together with the results of the latest low-energy beam test at the LNF Beam Test Facility with 450 MeV electrons.

The E760 Collaboration has studied the reaction p¯p→χ2→γγ using a hydrogen gas jet target in the Fermilab antiproton acumulator ring. The following values are obtained for the branching ratio and partial width to two photons; B(χ2→γγ)=(1.60±0.45)×10−4 and Γ(χ2→γγ)=321±95 eV.Received 2 October 1992DOI:https://doi.org/10.1103/PhysRevLett.70.2988©1993 American Physical Society

Fermilab experiment E-760 studies the resonant formation of charmonium states in proton-antiproton interactions using a hydrogen gas-jet target in the Antiproton Accumulator ring at Fermilab. Precision measurements of the mass and width of the charmonium states χc1,χc2, a direct measurement of the ψ’ width, and a new precision measurement of the J/ψ mass are presented.Received 3 February 1992DOI:https://doi.org/10.1103/PhysRevLett.68.1468©1992 American Physical Society

The resonance parameters of the χc0, the 13P0 state of charmonium, have been measured at the Fermilab Antiproton Accumulator in the reaction p̄p→χc0→γJ/ψ→γ(e+e−). A large data sample collected during the year 2000 run yields the results: M(χc0)=3415.4±0.4±0.2 MeV/c2, Γ(χc0)=9.8±1.0±0.1 MeV, B(χc0→p̄p)×B(χc0→γJ/ψ)×B(J/ψ→(e+e−))=(1.61±0.11±0.08)×10−7. Taking B(χc0→γJ/ψ) and B(J/ψ→e+e−) from the literature, we obtain B(χc0→p̄p)=(4.1±0.3+1.6−0.9)×10−4 and Γ(χc0→p̄p)=(4.0±0.4+1.6−0.9) keV.

The E760 Collaboration performed an experiment in the Antiproton Accumulator at Fermilab to study the two photon decay of the ηc(1 1S0) charmonium state formed in p¯p annihilations. This resulted in a new measurement of the mass Mηc=2988.3+3.3−3.1 MeV/c2 and of the product B(ηc→p¯p)×Γ(ηc→γγ) =(8.1+2.9−2.0) eV. We performed a search for the process p¯p→η′c(2 1S0)→γγ over a limited range of center-of-mass energies. Since no signal was observed, we derived upper limits on the product of branching ratios B(η′c→p¯p)×B(η′c→γγ) in the center-of-mass energy range 3584≤ √s ≤3624 MeV. We observed no signal for the nonresonant process p¯+p→γ+γ and obtain upper limits.Received 20 April 1995DOI:https://doi.org/10.1103/PhysRevD.52.4839©1995 American Physical Society

We report on a study of the angular distribution in the reaction ¯pp→χc2→Jψγ→e+e−γ. Using a sample of 1904 events, we find that the contribution of helicity zero in the formation process is B20<0.22 (90% C.L.), and that the normalized quadrupole amplitude in the radiative decay is a2=−0.14±0.06. The normalized radiative decay octupole amplitude a3 is found to be consistent with zero.Received 5 March 1993DOI:https://doi.org/10.1103/PhysRevD.48.3037©1993 American Physical Society

We report the branching ratios of the ${\ensuremath{\chi}}_{c2}{(1}^{3}{P}_{2})$ and ${\ensuremath{\chi}}_{c0}{(1}^{3}{P}_{0})$ charmonium resonances to two photons using event samples collected by Fermilab experiment E835 in the reactions $\overline{p}\stackrel{\ensuremath{\rightarrow}}{p}{\ensuremath{\chi}}_{c2}{(1}^{3}{P}_{2})[{\ensuremath{\chi}}_{c0}{(1}^{3}{P}_{0})].$ Our result for the ${\ensuremath{\chi}}_{c2}$ is $B({\ensuremath{\chi}}_{c2}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})=(1.35\ifmmode\pm\else\textpm\fi{}0.25\ifmmode\pm\else\textpm\fi{}0.12)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}.$ We set a 95% upper limit for the ${\ensuremath{\chi}}_{c0}$ branching ratio $B({\ensuremath{\chi}}_{c0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})$ at $2.09\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}.$

We provide a comprehensive description of experiment E835 at Fermilab, a high-precision experimental study of charmonium bound states. The c̄c states are formed in p̄p annihilations of cooled antiprotons stored in the Fermilab Antiproton Accumulator using a dense internal hydrogen gas-jet target. We describe the experimental strategies adopted for detecting the tiny c̄c resonant signals in the huge non-resonant hadronic background, and for measuring resonance parameters with high precision.

The neu_ART project aims at developing state of the art transmission imaging and computed tomography techniques, applied to art objects, by using neutrons as well as more conventional X-rays. In this paper a facility for digital X-ray radiography of large area paintings on canvas or wooden panels and for the X-ray tomography of large size wooden artifacts, recently installed in a protected area, is presented. The results of a K-edge radiography facility that will soon be installed in the same area are also shown.

Abstract The measurement of physics processes at new energy frontier experiments requires excellent spatial, time, and energy resolutions to resolve the structure of collimated high-energy jets. In a future Muon Collider, the beam-induced backgrounds (BIB) represent the main challenge in the design of the detectors and of the event reconstruction algorithms. The technology and the design of the calorimeters should be chosen to reduce the effect of the BIB, while keeping good physics performance. Several requirements can be inferred: i) high granularity to reduce the overlap of BIB particles in the same calorimeter cell; ii) excellent timing (of the order of 100 ps) to reduce the out-of-time component of the BIB; iii) longitudinal segmentation to distinguish the signal showers from the fake showers produced by the BIB; iv) good energy resolution (less than 10%/ √E ) to obtain good physics performance, as has been already demonstrated for conceptual particle flow calorimeters. Our proposal consists of a semi-homogeneous electromagnetic calorimeter based on lead fluoride crystals (PbF 2 ) read out by surface-mount UV-extended Silicon Photomultipliers (SiPMs): the Crilin calorimeter. In this paper, the performance of the Crilin calorimeter in the Muon Collider framework for hadron jets reconstruction has been analyzed. We report the characterisation of individual components together with the development of a small-scale prototype, consisting of 2 layers of 3 × 3 crystals each.

The muon collider represents one of the most promising solutions for a future machine exploring the high energy frontier, but several challenges due to the 2.2 $\mu$sec muon lifetime at rest have to be carefully considered. The LEMMA project is investigating the possibility of producing low emittance muon/antimuon pairs from the e$^+$e$^-$ annihilation process at threshold energy, resulting in small transverse emittance beams without any additional beam cooling. However most of the measurements available are performed at higher $\sqrt{s}$ values. It is therefore necessary to measure muons production in positron annihilation at threshold energy and compare the experimental results with the predictions in this specific energy regime. Apart from being a topic of physical interest by itself, these near to threshold measurements can have a sizeable impact on the estimation of the ultimate luminosity achievable in a muon collider with the LEMMA injection scheme.

Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadron and electron machines. They should thus be regarded as complementary. Parameters are given of 4 TeV and 0.5 TeV high luminosity \mumu colliders, and of a 0.5 TeV lower luminosity demonstration machine. We discuss the various systems in such muon colliders, starting from the proton accelerator needed to generate the muons and proceeding through muon cooling, acceleration and storage in a collider ring. Problems of detector background are also discussed.

Abstract A tracking detector composed of aluminized mylar drift tubes is under development for the Fermilab experiment 760. A prototype chamber has been constructed. Results on the longitudinal coordinate determined by charge division are given. Spatial resolution values below 2 mm (rms) were found, corresponding to

We present new precision measurements of the ψ(2S) total and partial widths from excitation curves obtained in antiproton–proton annihilations by Fermilab experiment E835 at the Antiproton Accumulator in the year 2000. A new technique of complementary scans was developed to study narrow resonances with stochastically cooled antiproton beams. The technique relies on precise revolution-frequency and orbit-length measurements, while making the analysis of the excitation curve almost independent of machine lattice parameters. We study the ψ(2S) meson through the processes p¯p→e+e− and p¯p→J/ψ+X→e+e−+X. We measure the width to be Γ=290±25(sta)±4(sys)keV and the combination of partial widths Γe+e−Γp¯p/Γ=579±38(sta)±36(sys)meV, which represent the most precise measurements to date.

Abstract In hadron therapy, the accelerated ions, interacting with the body of the patient, cause the fragmentation of both projectile and target nuclei. The fragments interact with the human tissues depositing energy both in the entrance channel and in the volume surrounding the tumor. The knowledge of the fragments features is crucial to determine the energy amount deposited in the human body, and - hence - the damage to the organs and to the tissues around the tumor target. The FOOT (FragmentatiOn Of Target) experiment aims at studying the fragmentation induced by the interaction of a proton beam (150-250 MeV/n) inside the human body. The FOOT detector includes an electronic setup for the identification of Z ≥ 3 fragments integrated with an emulsion spectrometer to measure Z ≤ 3 fragments. Charge identification by nuclear emulsions is based on the development of techniques of controlled fading of the particle tracks inside the nuclear emulsion, that extend the dynamical range of the films developed for the tracking of minimum ionising particles. The controlled fading strongly depends on temperature, relative humidity and treatment duration. In this study the performances in terms of charge separation of proton, helium and carbon particles, obtained on a batch of new emulsion films produced in Japan are reported.

Abstract The FOOT (FragmentatiOn Of Target) experiment is an international project designed to carry out the fragmentation cross-sectional measurements relevant for charged particle therapy (CPT), a technique based on the use of charged particle beams for the treatment of deep-seated tumors. The FOOT detector consists of an electronic setup for the identification of <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:mi>Z</m:mi> <m:mo>≥</m:mo> <m:mn>3</m:mn> </m:math> Z\ge 3 fragments and an emulsion spectrometer for <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:mi>Z</m:mi> <m:mo>≤</m:mo> <m:mn>3</m:mn> </m:math> Z\le 3 fragments. The first data taking was performed in 2019 at the GSI facility (Darmstadt, Germany). In this study, the charge identification of fragments induced by exposing an emulsion detector, embedding a <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:msub> <m:mrow> <m:mi mathvariant="normal">C</m:mi> </m:mrow> <m:mrow> <m:mn>2</m:mn> </m:mrow> </m:msub> <m:msub> <m:mrow> <m:mi mathvariant="normal">H</m:mi> </m:mrow> <m:mrow> <m:mn>4</m:mn> </m:mrow> </m:msub> </m:math> {{\rm{C}}}_{2}{{\rm{H}}}_{4} target, to an oxygen ion beam of 200 MeV/n is discussed. The charge identification is based on the controlled fading of nuclear emulsions in order to extend their dynamic range in the ionization response.

Abstract In recent years, a Muon collider has attracted a lot of interest in the high-energy physics community, thanks to its ability of achieving clean interaction signatures at multi-TeV collision energies in the most cost-effective way. Estimation of the physics potential of such an experiment must take into account the impact of beam-induced background on the detector performance, which has to be carefully evaluated using full detector simulation. Tracing of all the background particles entering the detector region in a single bunch crossing is out of reach for any realistic computing facility due to the unprecedented number of such particles. To make it feasible a number of optimisations have been applied to the detector simulation workflow. This contribution presents an overview of the main characteristics of the beam-induced background at a Muon collider, the detector technologies considered for the experiment and how they are taken into account to strongly reduce the number of irrelevant computations performed during the detector simulation. Special attention is dedicated to the optimisation of track reconstruction with the conformal tracking algorithm in this high-occupancy environment, which is the most computationally demanding part of event reconstruction.

In the path towards a muon collider with center of mass energy of 10 TeV or more, a stage at 3 TeV emerges as an appealing option. Reviewing the physics potential of such muon collider is the main purpose of this document. In order to outline the progression of the physics performances across the stages, a few sensitivity projections for higher energy are also presented. There are many opportunities for probing new physics at a 3 TeV muon collider. Some of them are in common with the extensively documented physics case of the CLIC 3 TeV energy stage, and include measuring the Higgs trilinear coupling and testing the possible composite nature of the Higgs boson and of the top quark at the 20 TeV scale. Other opportunities are unique of a 3 TeV muon collider, and stem from the fact that muons are collided rather than electrons. This is exemplified by studying the potential to explore the microscopic origin of the current $g$-2 and $B$-physics anomalies, which are both related with muons.

Detectors for new energy frontier experiments require excellent spatial, time, and energy resolutions to resolve the structure of collimated high-energy jets. In a future Muon Collider, the beam-induced backgrounds represent the main challenge for detector design and event reconstruction. Our proposal - Crilin - consists in a semi-homogeneous Cherenkov electromagnetic calorimeter based on P b F 2 crystals with surface-mount UV-extended Silicon Photomultipliers readout.

The resonance parameters of the charmonium ground state, ηc(11S0), have been measured by means of the reaction p̄p→ηc→γγ. The mass and total width are determined to be 2984.1±2.1±1.0 MeV/c2 and 20.4+7.7−6.7±2.0 MeV, respectively. The product of branching ratios B(p̄p→ηc)B(ηc→γγ) is determined to be 22.4+3.8−3.7±2.0×10−8, from which B(ηc→γγ)=1.87+0.32+0.95−0.31−0.50×10−4, and Γ(ηc→γγ)=3.8+1.1+1.9−1.0−1.0 keV are derived using B(ηc→p̄p)=(12±4)×10−4 from the literature.

We have studied the 3PJ (χc) states of charmonium in formation by antiproton–proton annihilations in experiment E835 at the Fermilab Antiproton Source. We report new measurements of the mass, width, and B(χcJ→p¯p)Γ(χcJ→J/ψ+anything) for the χc1 and χc2 by means of the inclusive reaction p¯p→χcJ→J/ψ+anything→(e+e−)+anything. Using the subsample of events where χcJ→γ+J/ψ→γ+(e+e−) is fully reconstructed, we derive B(χcJ→p¯p)Γ(χcJ→J/ψ+γ). We summarize the results of the E760 (updated) and E835 measurements of mass, width and B(χcJ→p¯p)Γ(χcJ→J/ψ+γ) (J=0,1,2) and discuss the significance of these measurements.

This paper describes the development and characterization of a ΔE-TOF detector composed of a plastic scintillator bar coupled at both ends to silicon photomultipliers. This detector is a prototype of a larger version which will be used in the FOOT (FragmentatiOn Of Target) experiment to identify the fragments produced by ion beams accelerated onto a hydrogen-enriched target. The final ΔE-TOF detector will be composed of two layers of plastic scintillator bars with orthogonal orientation and will measure, for each crossing fragment, the energy deposited in the plastic scintillator (ΔE), the time of flight (TOF), and the coordinates of the interaction position in the scintillator. To meet the FOOT experimental requirements, the detector should have energy resolution of a few percents and time resolution of 70 ps, and it should allow to discriminate multiple fragments belonging to the same event. To evaluate the achievable performances, the detector prototype was irradiated with protons of kinetic energy in the 70–230 MeV range and interacting at several positions along the bar. The measured energy resolution σΔE∕ΔE was 6–14%, after subtracting the fluctuations of the deposited energy. A time resolution σ between 120 and 180 ps was obtained with respect to a trigger detector. A spatial resolution σ of 1.9 cm was obtained for protons interacting at the center of the bar.

We present measurements of the 2π0 mass spectrum in proton—antiproton annihilations. The f2 (1520) resonance is strongly produced in the 3π0 channel. Its production along with an η is observed, but strongly suppressed. Other features are seen in the data, including the f2 (1270) and structures at 2000 MeV/c2 and above.

We have observed exclusive decays of the ψ′ in an experiment where the ψ′ is formed in antiproton-proton annihilations. We report the branching ratios B(ψ′→e+e−)=(8.3±0.5stat±0.7syst)×10−3, B(ψ′→J/ψπ+π−)=0.283±0.021stat±0.020syst, B(ψ′→J/ψπ0π0)=0.184±0.019stat±0.013syst, B(ψ′→J/ψη)=0.032±0.010stat±0.002syst. Received 3 September 1996DOI:https://doi.org/10.1103/PhysRevD.55.1153©1997 American Physical Society

We report on a search by Fermilab experiment E835 for the η′c (21S0) charmonium resonance in the process ¯p→pη′c→γγ. No signal was observed and, based on 34 pb−1 integrated luminosity, we determine the following upper limits (90% confidence level) to the product of the branching ratios for a resonance mass in the region 3575–3660 MeV/c2: Br(η′c→¯pp)×Br(η′c→γγ)<12.0×10−8 for Γ=5 MeV; <5.9×10−8 for Γ=10 MeV; <4.8×10−8 for Γ=15 MeV. Combining the present data with those of the predecessor experiment, E760, the upper limits become 8.0×10−8, 5.0×10−8, and 4.5×10−8, respectively. In the restricted region 3589–3599 MeV/c2, where a candidate was reported by the Crystal Ball experiment, we obtain the following limits from the combined E760–E835 experiments: Br(η′c→¯pp)×Br(η′c→γγ)<5.6×10−8 for Γ=5 MeV; <3.7×10−8 for Γ=8 MeV. A comparison of these with other experimental results is presented.Received 18 January 2001DOI:https://doi.org/10.1103/PhysRevD.64.052003©2001 American Physical Society

We present the first measurement of the angular distribution for the exclusive process p¯p→ψ(2S)→e+e− based on a sample of 6844 events collected by the Fermilab E835 experiment. We find that the angular distribution is well described by the expected functional form dNdcosθ∗∝1+λcos2θ∗, where θ∗ is the angle between the antiproton and the electron in the center of mass frame, with λ=0.67±0.15(stat)±0.04(sys). The measured value for λ implies a small but non-zero ψ(2S) helicity 0 formation amplitude in p¯p, comparable to what is observed in J/ψ decays to baryon pairs.

The resonance parameters of χc0, the 31P0 resonance of charmonium, have been measured at the Fermilab Antiproton Accumulator by means of the reaction ¯pp→χc0→γJ/ψ→γ(e+e−). The results are M(χc0)=3417.4+1.8−1.9±0.2MeV/c2, Γ(χc0)=16.6+5.2−3.7±0.1MeV, and Γ(χc0→¯pp)×B(χc0→J/ψγ)×B(J/ψ→e+e−)=2.89+0.67−0.53±0.14eV. Using known branching ratios we also obtain Γ(χc0→¯pp)=8.0+1.9+3.5−1.5−1.9keV. These results are discussed in relation to the other χcJ states and to theoretical predictions.Received 3 June 1999DOI:https://doi.org/10.1103/PhysRevLett.83.2902©1999 American Physical Society

Differential cross sections for pp elastic scattering have been measured for very small momentum transfers at six different incident antiproton momenta in the range 3.7 to 6.2 GeV/c by the detection of recoil protons at scattering angles close to 90°. Forward scattering parameters σT, b, and ϱ have been determined. For the ϱ-parameter, up to an order of magnitude higher level of precision has been achieved compared to that in earlier experiments. It is found that existing dispersion theory predictions are in disagreement with our results for the ϱ-parameter.

We have performed an experiment in the Antiproton Accumulator at Fermilab to study two-body neutral final states formed in ¯pp annihilations. Differential cross sections are determined in the center-of-mass energy range 2.911<√s<3.686 GeV for the final states π0π0, ηπ0, ηη, π0γ, and γγ. The energy dependence of differential cross sections at 90° in the center of mass is studied to test the predictions of phenomenological QCD scaling hypotheses which predict power-law dependence.Received 30 December 1996DOI:https://doi.org/10.1103/PhysRevD.56.2509©1997 American Physical Society

Fermilab experiment E835 has observed (-)pp annihilation production of the charmonium state chi(c0) and its subsequent decay into pi(0)pi(0). Although the resonant amplitude is an order of magnitude smaller than that of the nonresonant continuum production of pi(0)pi(0), an enhanced interference signal is evident. A partial wave expansion is used to extract physics parameters. The amplitudes J=0 and 2, of comparable strength, dominate the expansion. Both are accessed by L=1 in the entrance (-)pp channel. The product of the input and output branching fractions is determined to be B((-)pp-->chi(c0))xB(chi(c0)-->pi(0)pi(0))=(5.09+/-0.81+/-0.25)x10(-7).

Abstract The Italian Neutron Experimental Station (INES) located at the ISIS pulsed neutron source (Didcot, United Kingdom) provides a thermal neutron beam mainly used for diffraction analysis. A neutron transmission imaging system was also developed for beam monitoring and for aligning the sample under investigation. Although the time-of-flight neutron diffraction is a consolidated technique, the neutron imaging setup is not yet completely characterized and optimized. In this paper the performance for neutron radiography and tomography at INES of two scintillator screens read out by two different commercial CCD cameras is compared in terms of linearity, signal-to-noise ratio, effective dynamic range and spatial resolution. In addition, the results of neutron radiographies and a tomography of metal alloy test structures are presented to better characterize the INES imaging capabilities of metal artifacts in the cultural heritage field.

Within the neu_ART project, funded by Regione Piemonte (Italy), a team of specialists in different scientific fields coming from Istituto Nazionale di Fisica Nucleare (INFN), Physics Department of University of Torino and Centro Conservazione e Restauro (CCR) “La Venaria Reale” has developed a new digital X-ray apparatus expressly designed for painted canvas and panels up to about 3 m × 4 m. Compared to all other systems scanning time is faster, the procedure to obtain the whole radiography is easier and images are available in real time. This apparatus has been widely tested on artworks restored at CCR “La Venaria Reale”, allowing to study and optimize the operating parameters and to evaluate its performance, thanks to the feedback provided by professionals involved in the activities of conservation. Supported by the results presented in this work, restorers had the possibility to investigate the materials characteristics and to plan the operating strategy in advance: indeed, radiographs revealed areas with losses of paint, repainted areas, canvas damages, hidden pictures, writings and previous restorations. The X-Ray system for Digital Radiography is integrated in a more complex apparatus that can be used also for computed tomography of voluminous objects up to 2.5 m in height and 2 m in width, making the apparatus developed in the neu_ART project a unique and comprehensive tool at conservators' disposal.

Charged particle therapy exploits proton or 12C beams to treat deep-seated solid tumors. Due to the advantageous characteristics of charged particles energy deposition in matter, the maximum of the dose is released to the tumor at the end of the beam range, in the Bragg peak region. However, the beam nuclear interactions with the patient tissues induces fragmentation both of projectile and target nuclei and needs to be carefully taken into account. In proton treatments, target fragmentation produces low energy, short range fragments along all the beam range, which deposit a non negligible dose in the entry channel. In 12C treatments the main concern is represented by long range fragments due to beam fragmentation that release their dose in the healthy tissues beyond the tumor. The FOOT experiment (FragmentatiOn Of Target) of INFN is designed to study these processes, in order to improve the nuclear fragmentation description in next generation Treatment Planning Systems and the treatment plans quality. Target (16O and 12C nuclei) fragmentation induced by –proton beams at therapeutic energies will be studied via an inverse kinematic approach, where 16O and 12C therapeutic beams impinge on graphite and hydrocarbon targets to provide the nuclear fragmentation cross section on hydrogen. Projectile fragmentation of 16O and 12C beams will be explored as well. The FOOT detector includes a magnetic spectrometer for the fragments momentum measurement, a plastic scintillator for ΔE and time of flight measurements and a crystal calorimeter to measure the fragments kinetic energy. These measurements will be combined in order to make an accurate fragment charge and isotopic identification.

The study that we present is part of the preparation work for the setup of the FOOT (FragmentatiOn Of Target) experiment whose main goal is the measurement of the double differential cross sections of fragments produced in nuclear interactions of particles with energies relevant for particle therapy. The present work is focused on the characterization of the gas-filled drift chamber detector composed of 36 sensitive cells, distributed over two perpendicular views. Each view consists of six consecutive and staggered layers with three cells per layer. We investigated the detector efficiency and we performed an external calibration of the space–time relations at the level of single cells. This information was then used to evaluate the drift chamber resolution. An external tracking system realized with microstrip silicon detectors was adopted to have a track measurement independent on the drift chamber. The characterization was performed with a proton beam at the energies of 228 and 80 MeV. The overall hit detection efficiency of the drift chamber has been found to be 0.929±0.008, independent on the proton beam energy. The spatial resolution in the central part of the cell is about 150±10 μ m and 300±10 μ m and the corresponding detector angular resolution has been measured to be 1.62±0.16 mrad and 2.1±0.4 mrad for the higher and lower beam energies, respectively. In addition, the best value on the intrinsic drift chamber resolution has been evaluated to be in the range 60−100 μ m. In the framework of the FOOT experiment, the drift chamber will be adopted in the pre-target region, and will be exploited to measure the projectile direction and position, as well as for the identification of pre-target fragmentation events.

FOOT (FragmentatiOn Of Target) is an applied nuclear physics experiment conceived to conduct high-precision cross section measurements of nuclear fragmentation processes relevant for particle therapy and radiation protection in space. These measurements are important to estimate the physical and biological effects of nuclear fragments, which are produced when energetic particle beams penetrate human tissue. A component of the FOOT experiment is the ΔE-TOF system. It is designed to measure energy loss and time-of-flight of nuclear fragments produced in particle collisions in thin targets in order to extract their charge and velocity. The ΔE-TOF system is composed of a start counter, providing the start time for the time-of-flight, and a 40 × 40 cm2 wall of thin plastic scintillator bars, providing the arrival time and energy loss of the fragments passing through the detector. Particle charge discrimination can be achieved by correlating the energy loss in the scintillator bars with the measured time-of-flight. Recently, we have built a full-size ΔE-TOF detector. In this work, we describe the energy and time-of-flight calibration procedure and assess the performance of this system. We use data acquired during beam tests at CNAO with proton and 12C beams and at GSI with 16O beams in the energy range relevant for particle therapy, i.e., from 60 to 400 MeV/u. For heavy fragments (C and O), we obtain energy and time resolutions ranging from 4.0 to 5.2% and from 54 to 76 ps, respectively. The procedure is also applied to a fragmentation measurement of a 400 MeV/u 16O beam on a 5 mm carbon target, showing that the system is able to discriminate the charges of impinging fragments.

A proportional chamber made with aluminized mylar drift tubes is described. The design is optimized for lightness and good performance in drift time and charge division on resistive sense wires. The design makes it possible to minimize the effect of failures, since a broken wire does not prevent the rest of the chamber from operation, and allows a very low weight. The use of resistive wire, not common to other detectors of this kind, makes it possible to measure the longitudinal coordinate by comparing the charges collected at the two anode ends. The design of the chamber is described, its readout characteristics are examined, and preliminary results are reported.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with heavy absorber plates, and read out by wavelength-shifting (WLS) fibers is being studied as a calorimeter option for detectors at the upgraded High-Luminosity LHC (HL-LHC) collider at CERN. A prototype has been exposed to electron beams of different energies at the INFN Frascati (Italy) Beam Test Facility. This paper presents results from the studies performed on the prototype, such as signal amplitudes, light yield and energy resolution.

In a carbon ion treatment the nuclear fragmentation of both target and beam projectiles impacts on the dose released on the tumor and on the surrounding healthy tissues. Carbon ion fragmentation occurring inside the patient body has to be studied in order to take into account this contribution. These data are also important for the development of the range monitoring techniques with charged particles. The production of charged fragments generated by carbon ion beams of 115-353 MeV/u kinetic energy impinging on carbon, oxygen, and hydrogen targets has been measured at the CNAO particle therapy center (Pavia, Italy). The use of thin targets of graphite (C), PMMA (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sub> ) and polyvinyl-toluene [plastic scintillator (PS), CbHa] allowed to measure fragments production cross sections, exploiting a time-of-flight (ToF) technique. PS detectors have been used to perform the ToF measurements, while LYSO crystals have been used for the deposited energy measurement and to perform particle identification. Cross sections have been measured at 90° and 60° with respect to the beam direction. The measured proton, deuteron, and triton differential production cross sections on C, O, and H, obtained exploiting the target subtraction strategy, are presented here as a function of the fragment kinetic energy.

We describe our R&D effort to develop radiation-hard scintillating and wavelength shifting fibers by doping fused-silica with cerium. This new type of cerium-doped fiber potentially offers myriad new applications in calorimeters for high-energy physics, tracking systems, and profiling of charged particle beams.

The Muon Collider is a possible option for the next generation of high energy collider machines. It would permit to achieve the energy frontier in lepton collisions, without occurring in significant synchrotron radiation losses as in electrons rings. Among the technological challenges in the realization of such a machine, the treatment of the beam-induced background is one of the most critical issues for the detectors. Beams with intensity of the order of $10^{12}$ muons per bunch are necessary to obtain the desired luminosity, therefore the muons decay rate is very high. Beam decay products and subsequent particles from secondary interactions with the machine elements can reach the interaction point, limiting the physical performance of the detector. A study of the beam-induced background is presented together with possible strategies for its reduction. Preliminary results on the reconstruction of a benchmark process, $\mu^+\mu^-\to H\nu\bar{\nu}\to b \bar{b}\nu\bar{\nu}$, including the beam-induced background are illustrated as demonstration of physics measurements feasibility in this harsh environment.

We report on the decay to two photons of the χ c 0 (1 3 P 0 ) charmonium resonance formed in pp interactions at Fermilab experiment E835.We have measured the product of branching ratios BR(χ c 0 → pp) × BR(χ c 0 → γ γ ) = (6.52 ± 1.18(stat) +0.48 -0.72 (sys)) × 10 -8 .Using values from the 2002 PDG, this measurement leads to the partial width Γ (χ c 0 → γ γ ) = 2.9 ± 0.9 keV.

A Muon Collider represents a possible option for the next generation of high-energy machines.Among the technological challenges in the realization of such a machine, the mitigation of the beam-induced background is one of the most critical issues for the experiments.At the desired instantaneous luminosity, the decay rate of the circulating muons is very high, the decay products and subsequent particles from their interactions with the machine elements can reach the detector and compromise its performance.In this contribution, the results of a first preliminary study is presented of the beam-induced background effects on the detector response in the case of muon beams collisions at a center of mass energy of 1.5 TeV and some background mitigation strategies are illustrated.

Abstract A threshold gas Cherenkov counter is used in Fermilab Experiment 760 to tag electrons in the detection of charmonium states. Mechanical structures and mirrors were built with carbon-fiber-epoxy composites, resulting in a light weight detector covering 2π in azimuthal angle. The counter is operated at atmospheric pressure with different gases, CO 2 and Freon 13, respectively in the two cells at small and large polar angles, to maximize pion rejection. Design considerations, construction details, and performance of the counter are described.

We report the first observation of the (radiative) decay $\frac{J}{\ensuremath{\psi}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}\ensuremath{\gamma}$. Our data are from an experiment in which $\frac{J}{\ensuremath{\psi}}$ is formed in antiproton-proton annihilations. The observed rate is consistent with a QED calculation based on final state radiation. Our measurement gives a branching ratio for this mode of (8.8\ifmmode\pm\else\textpm\fi{}1.3\ifmmode\pm\else\textpm\fi{}0.4)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$ for $\ensuremath{\gamma}$ energy&gt;100 MeV.

In the experiment R704 at the CERN Intersecting Storage Rings, the two p-wave charmonium states χ1 and χ2 were formed directly in proton-antiproton annihilation, and detected through the decay chain χj→γ+Jψ→ψ+e+e−. The angular d istributions of the events found are studied here. A maximum likehood analysis shows that χ1 radiative transition to the Jψ is compatible with a pure dipole. Indications of a nonzero, positive quadropole contribution to the χ2 radiative transition are found. Finally, it is found that the χ2 data are consistent with the conventional assumption that a single quark radiates the photon in the transition from the χ2 to the Jψ.

We have determined the following ${\ensuremath{\psi}}^{\ensuremath{'}}$ branching ratios using the large event sample collected by Fermilab experiment E835 in the reaction $p\overline{p}\ensuremath{\rightarrow}{\ensuremath{\psi}}^{\ensuremath{'}}:$ $\mathcal{B}({\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}})=(7.4\ifmmode\pm\else\textpm\fi{}0.2\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3},$ $\mathcal{B}({\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}J/\ensuremath{\psi}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0})=(18.7\ifmmode\pm\else\textpm\fi{}0.9\ifmmode\pm\else\textpm\fi{}1.3)%$ and $\mathcal{B}({\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\eta})=(4.1\ifmmode\pm\else\textpm\fi{}0.3\ifmmode\pm\else\textpm\fi{}0.5)%.$

Particle therapy uses protons or $^{12}$C beams for the treatment of deep-seated solid tumors. Due to the features of the energy deposition of charged particles in matter, a limited amount of dose is released to the healthy tissue in the beam entrance region, while the maximum of the dose is released to the tumor at the end of the beam range, in the Bragg peak region. However nuclear interactions between beam and patient tissues induce fragmentation both of projectile and target. This has to be carefully taken into account since different ions have different effectiveness in producing a biological damage. par In $^{12}$C treatments the main concern are long range forward emitted secondary ions produced in projectile fragmentation that release dose in the healthy tissue after the tumor. Instead, in a proton treatment, the target fragmentation produces low energy, short range fragments along all the beam range. The FOOT experiment (FragmentatiOn Of Target) is designed to study these processes. Target nuclei ($^{16}$O, $^{12}$C) fragmentation induced by 150-250 MeV proton beam will be studied by means of the inverse kinematic approach: $^{16}$O,$^{12}$C therapeutic beams, at the quoted kinetic energy per nucleon, collide on graphite and hydrocarbons target. The cross section on Hydrogen can be then extracted by subtraction. This configuration explores also the projectile fragmentation of these O and C beams, or other ions of therapeutic interest, such as $^4$He for instance. The detector includes a magnetic spectrometer based on silicon pixel and strip detectors, a scintillating crystal calorimeter able to stop the heavier produced fragments, and a $\Delta E$ detector, with TOF capability, to achieve the needed energy resolution and particle identification. In addition to the electronic apparatus, an alternative setup based on the concept of the "Emulsion Cloud Chamber", coupled with the interaction region of the electronic FOOT setup, will provide the measurement of lighter charged fragments: protons, deuterons, tritons and Helium nuclei. The FOOT data taking is foreseen in the available experimental rooms existing in the presently operational charged particle therapy facilities in Europe, and possibly at GSI. An initial phase with the emulsion setup will start in early 2018, while the complete electronic detector will take data starting in 2019. In this work a general description of the FOOT experiment and of its expected performances is presented.

Physics at a multi-TeV muon collider needs a change of perspective for the detector design due to the large amount of background induced by muon beam decays. Preliminary studies, based on simulated data, on the composition and the characteristics of the particles originated from the muon decays and reaching the detectors are presented here. The reconstruction performance of the physics processes $H\to b\bar b$ and $Z\to b\bar b$ has been investigated for the time being without the effect of the machine induced background. A preliminary study of the environment hazard due to the radiation induced by neutrino interactions with the matter is presented using the FLUKA simulation program.

A prototype for a sampling calorimeter made out of cerium fluoride crystals interleaved with tungsten plates, and read out by wavelength-shifting fibres, has been exposed to beams of electrons with energies between 20 and 150 GeV, produced by the CERN Super Proton Synchrotron accelerator complex. The performance of the prototype is presented and compared to that of a Geant4 simulation of the apparatus. Particular emphasis is given to the response uniformity across the channel front face, and to the prototype׳s energy resolution.

The study of nuclear fragmentation plays a central role in many important applications: from the study of Particle Therapy (PT) up to radiation protection for space (RPS) missions and the design of shielding for nuclear reactors. The FragmentatiOn Of Target (FOOT) collaboration aims to study the nuclear reactions that describe the interactions with matter of different light ions (like <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">H</mml:mi><mml:mspace width="0.3333em" class="nbsp" /></mml:mrow><mml:none /><mml:none /><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m3"><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">H</mml:mi><mml:mi mathvariant="normal">e</mml:mi><mml:mspace width="0.3333em" class="nbsp" /></mml:mrow><mml:none /><mml:none /><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m4"><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">C</mml:mi><mml:mspace width="0.3333em" class="nbsp" /></mml:mrow><mml:none /><mml:none /><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>12</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m5"><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:none /><mml:none /><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>16</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> ) of interest for such applications, performing double differential fragmentation cross section measurements in the energy range of interest for PT and RPS. In this manuscript, we present the analysis of the data collected in the interactions of an oxygen ion beam of 400 MeV/u with a graphite target using a partial FOOT setup, at the GSI Helmholtz Center for Heavy Ion Research facility in Darmstadt. During the data taking the magnets, the silicon trackers and the calorimeter foreseen in the final FOOT setup were not yet available, and hence precise measurements of the fragments kinetic energy, momentum and mass were not possible. However, using the FOOT scintillator detectors for the time of flight (TOF) and energy loss (Δ E ) measurements together with a drift chamber, used as beam monitor, it was possible to measure the elemental fragmentation cross sections. The reduced detector set-up and the limited available statistics allowed anyway to obtain relevant results, providing statistically significant measurements of cross sections eagerly needed for PT and RPS applications. Whenever possible the obtained results have been compared with existing measurements helping in discriminating between conflicting results in the literature and demonstrating at the same time the proper functioning of the FOOT ΔE-TOF system. Finally, the obtained fragmentation cross sections are compared to the Monte Carlo predictions obtained with the FLUKA software.

I present preliminary results on the search for $h_c$ in its $\eta_c\gamma$ and $J/\psi\pi^0$ decay modes. We observe an excess of \eta_c\gamma$ events near 3526 MeV that has a probability ${\cal P} \sim 0.001$ to arise from background fluctations. The resonance parameters are $M=3525.8 \pm 0.2 \pm 0.2 $MeV, $\Gamma\leq$ 1 MeV, and $10.6\pm 3.7\pm3.4(br) < \Gamma_{\bar{p}p}B_{\eta_c\gamma} < 12.8\pm 4.8\pm4.5(br) $eV. We find no event excess within the search region in the $J/\psi\pi^0$ mode.

Two layers of proportional drift tubes (aluminum mylar straws) are staggered in two cylindrical light chambers to measure charged particles’ azimuthal angle. To stand the high rates (∼10kHz/cm2) and minimize the pile-up of the high luminosity experiment 835 at FNAL, a fast ASIC Amplifier-Shaper-Discriminator (ASD-8B) was chosen. The front-end electronics, designed exclusively with SMD components, was mounted on the downstream end plug of each chamber to avoid oscillations and noise. Design, construction and operational performances of these detectors are presented.

From the measurement of e+e- pairs from the reaction p̄p→e+e- at the CERN-ISR, using an antiproton beam and a hydrogen jet target, we derived upper limits for the proton magnetic form factor in the time-like region at Q2⋍8.9(GeVc)2 and Q2⋍12.5(GeVc)2.

The Pierre Auger Observatory will study cosmic rays with energy exceeding 10/sup 19/ eV. The experiment will measure properties of extensive air showers with a hybrid detector consisting of a surface array and an atmospheric fluorescence telescope. This paper presents the characteristics and performance of the optical system for the fluorescence detector prototype. The system adopts a Schmidt camera design with a diaphragm to remove coma aberration. A large spherical mirror (approximately 3.6/spl times/3.6 m, with radius of curvature 3.47 m), segmented in 49 trapezoidal elements, is supported by a mechanical structure, where segments are positioned on the meridians of the spherical cap. At the diaphragm, an absorption filter is installed to preferentially transmit the nitrogen fluorescence light. The construction technique, image characteristics, and results of tests performed on the system are discussed.

I present preliminary results on the search for hc in its ηcγ and J/ψπ0 decay modes. We observe an excess of ηcγ events near 3526 MeV that has a probability P∼0.001 to arise from background fluctations. The resonance parameters are M=3525.8±0.2±0.2MeV, Γ⩽1MeV, and 10.6±3.7±3.4(br)<Γp¯pBηcγ<12.8±4.8±4.5(br)eV. We find no event excess within the search region in the J/ψπ0 mode.

We have evaluated the performance of a Ce-doped fused-silica fiber as wavelength shifter coupled to a CeF3 crystal using electron beams at CERN . The pulse shape and collection efficiency were measured using irradiated (100 kGy) and un-irradiated fibers. In addition, we evaluated the light yield of various Ce-doped fibers and explored the possibility of using them in the future, including for precision timing applications in a high-luminosity collider environment.

Particle therapy uses proton or 12C beams for the treatment of deep-seated solid tumors. Due to the features of energy deposition of charged particles a small amount of dose is released to the healthy tissue in the beam entrance region, while the maximum of the dose is released to the tumor at the end of the beam range, in the Bragg peak region. However nuclear interactions between beam and patient tissues induce fragmentation both of projectile and target and must be carefully taken into account. In 12C treatments the main concern are long range fragments due to projectile fragmentation that release dose in the healthy tissue after the tumor, while in proton treatment the target fragmentation produces low energy, short range fragments along all the beam range. The FOOT experiment (FragmentatiOn Of Target) is designed to study these processes. Target nuclei (16O,12C) fragmentation induced by 150-250 AMeV proton beam will be studied via inverse kinematic approach. 16O,12C therapeutic beams, with the quoted kinetic energy, collide on graphite and hydrocarbons target to provide the cross section on Hydrogen. This configuration explores also the projectile fragmentation of these 16O,12C beams. The detector includes a magnetic spectrometer based on silicon pixel detectors, a scintillating crystal calorimeter with TOF capabilities, able to stop the heavier fragments produced, and a ∆E detector to achieve the needed energy resolution and particle identification. An alternative setup of the experiment will exploit the emulsion chamber capabilities. A specific emulsion chambers will be coupled with the interaction region of the FOOT setup to measure the production in target fragmentation of light charged fragments as protons, deuterons, tritons and Helium nuclei. The FOOT data taking is foreseen at the CNAO experimental room and will start during early 2018 with the emulsion setup, while the complete electronic detector will take data since 2019

Experimental results and simulation models show that crystals might play a relevant role for the development of new generations of high-energy and high-intensity particle accelerators and might disclose innovative possibilities at existing ones. In this paper we describe the most advanced manufacturing techniques of crystals suitable for operations at ultra-high energy and ultra-high intensity particle accelerators, reporting as an example of potential applications the collimation of the particle beams circulating in the Large Hadron Collider at CERN, which will be upgraded through the addition of bent crystals in the frame of the High Luminosity Large Hadron Collider project.

Particle therapy uses proton and ion beams to treat deep-seated solid tumors, exploiting the favorable energy deposition profile of charged particles. Nuclear interactions with patient tissues can induce fragments production that must be taken into account in treatment planning: in proton treatments target fragmentation produces low-energy, short-range fragments depositing a non-negligible dose in the entry channel, while in heavier-ion beam treatments long-range fragments due to projectile fragmentation release dose in tissues surrounding the tumor. The FOOT experiment aims to study these processes to improve the nuclear interactions description in next generation Treatment Planning Systems softwares and hence the treatments quality. Target (16O and 12C) fragmentation induced by 150–250 MeV proton beams will be studied via inverse kinematics: 16O and 12C beams (150–250 MeV/u) collide on graphite and hydrocarbon targets to provide nuclear fragmentation cross sections on hydrogen. The projectile fragmentation of these beams will be explored as well. The FOOT detector includes a magnetic spectrometer to measure fragments momentum, a plastic scintillator for ΔE and TOF measurements and a scintillating crystal calorimeter to measure fragments kinetic energy. These measurements will be combined to accurately identify fragments charge and mass.

Physics at a multi-TeV muon collider needs a change of perspective for the detector design due to the large amount of background induced by muon beam decays. Preliminary studies, based on simulated data, on the composition and the characteristics of the particles originated from the muon decays and reaching the detectors are presented here. The reconstruction performance of the physics processes $H\to b\bar b$ and $Z\to b\bar b$ has been investigated for the time being without the effect of the machine induced background. A preliminary study of the environment hazard due to the radiation induced by neutrino interactions with the matter is presented using the FLUKA simulation program.

A threshold gas Cherenkov counter is used in Fermilab experiment 835 to tag electrons from the decay of charmonium states. It is an improved version of the counter used in a previous charmonium experiment, E760. The new features of the design, the technique used to build a set of ellipsoidal mirrors, and the counter performance are presented.

In an experiment performed at the CERN Intersecting Storage Rings as a part of an energy scan to detect the ηc formation in pp annihilation, we studied the reaction pp→φφ→K+K−K+K−. The total cross section has been determined to be 25.0± 7.4±3.8 nb.

Fermilab experiment E835 has studied reactions $\overline{p}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0},{\ensuremath{\pi}}^{0}\ensuremath{\eta},\ensuremath{\eta}\ensuremath{\eta},$ ${\ensuremath{\pi}}^{0}{\ensuremath{\eta}}^{\ensuremath{'}}$ and $\ensuremath{\eta}{\ensuremath{\eta}}^{\ensuremath{'}}$ in the energy region of the ${\ensuremath{\chi}}_{c0}({1}^{3}{P}_{0})$ from $3340$ MeV to $3470$ MeV. Interference between resonant and continuum production is observed in the ${\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ and $\ensuremath{\eta}\ensuremath{\eta}$ channels, and the product of the input and output branching fractions is measured. Limits on resonant production are set for the ${\ensuremath{\pi}}^{0}\ensuremath{\eta}$ and ${\ensuremath{\pi}}^{0}{\ensuremath{\eta}}^{\ensuremath{'}}$ channels. An indication of interference is observed in the $\ensuremath{\eta}{\ensuremath{\eta}}^{\ensuremath{'}}$ channel. The technique for extracting resonance parameters in an environment dominated by continuum production is described.

We have measured several branching ratios for ψ′ decay using the data collected by the FNAL E835 experiment during the year 2000, obtaining B(ψ′→e+e−)=0.0068±0.0001±0.0004, B(ψ′→J/ψπ+π−)=0.292±0.005±0.018, B(ψ′→J/ψπ0π0)=0.167±0.005±0.014, and B(ψ′→J/ψη)=0.028±0.002±0.002. We also present a measurement of the dipion mass distribution in the decays ψ′→J/ψππ.Received 6 August 2004DOI:https://doi.org/10.1103/PhysRevD.71.032006©2005 American Physical Society

The measurement of physics processes at new energy frontier experiments requires excellent spatial, time, and energy resolutions to resolve the structure of collimated high-energy jets. Calorimeters, as other detectors, must face this increasing performance demand. In a future TeV-scale Muon Collider, the beam-induced background (BIB) represents the main challenge in the design of the detectors and of the event reconstruction algorithms and can pose serious limitations to the physics performance. However, it is possible to reduce the BIB impact on the Muon Collider calorimeter by exploiting some of its characteristics and by ensuring high granularity, excellent timing, longitudinal segmentation and good energy resolution. The proposed R&amp;D is an innovative semi-homogeneous electromagnetic calorimeter based on stackable modules of lead fluoride crystals (PbF 2 ) readout by surface-mount UV-extended Silicon Photomultipliers (SiPMs): the Crilin calorimeter (CRystal calorImeter with Longitudinal INformation). The calorimeter should operate in a very harsh radiation environment, withstanding yearly a neutron flux of 10 14 n1MeV /cm 2 and a dose of 100 krad. In this paper, the radiation tolerance measured in several irradiation campaigns and the timing performances evaluated during a test beam at CERN-H2 with 120-GeV electron are discussed. A description of the latest prototype Proto-1, that will be shortly tested, is also provided.

A tracking detector made of scintillating fibers wound on a cylinder is being developed at FNAL, for the experiment E835 (study of the spectroscopy of charmonium formed in pp annihilations, at the Fermilab Antiproton Accumulator). The tracker will be used for the measurement of the polar angle, i.e. of the longitudinal coordinate. The small amount of light from the fibers will be detected by solid state devices (Visible Light Photon Counters) with very high QE, currently being developed and tested by the D0 Fiber Tracking Group at FNAL. This paper reports the performance of a prototype fiber tracker, as measured at FNAL. We present results on light yield/mip, attenuation, efficiency, homogeneity of response and cross-talk. The data are then compared with Monte Carlo predictions. We measured an average number of 14 photoelectrons per mip and a very low noise level. An efficiency greater than 99% is foreseen for the future double layered tracker.

The main goal of the FOOT (FragmentatiOn Of Target) experiment is the measurement of the differential cross sections as a function of energy and direction of the produced fragments in the nuclear interaction between a ion beam (proton, helium, carbon, ...) and different targets (proton, carbon, oxygen, ...). Depending on the beam energy, the purpose of the measurements is twofold: in the [150-400] MeV/u range, the data will be used to evaluate the side effects of the nuclear fragmentation in the hadrontherapy treatment, while in the [700-1000] MeV/u range it will be used to optimize the shielding of spaceships for long term space missions. The experiment has been funded by the INFN since September 2017 and it is currently in the construction phase. An overview of the detector, of the results obtained in several beam tests and of the expected performances will be presented.

This work introduces an experimental test of the new proposal for a low–emittance muon accelerator (LEMMA). A low–emittance muon beam is obtained from the e$^+$ e$^-$ → μ$^+$ μ$^-$ annihilation process at the threshold energy of 45 GeV eliminating the need for a dedicated muon cooling system. A series of two testbeam campaigns were carried out at CERN to validate this concept. The experimental setup is presented together with first preliminary results from the obtained data.

A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with absorber plates made of tungsten, and read out by wavelength-shifting fibres has been tested with high-energy electron beams at the CERN SPS H4 beam line, as well as with lower-energy beams at the INFN Frascati Beam Test Facility in Italy. Energy resolution studies revealed a low stochastic term (<10%/E). This result, combined with high radiation hardness of the material used, marks this sampling calorimeter as a good candidate for the detectors׳ forward regions during the high luminosity phase of LHC.

The investigation of the energy frontier in physics requires novel concepts for future colliders. The idea of a muon collider is very appealing since it would allow to study particle collisions at up to tens of TeV energy, while offering a cleaner experimental environment with respect to hadronic colliders. One key element in the muon collider design is the low-emittance muon production. Recently,the Low EMittance Muon Accelerator (LEMMA) collaboration has explored the muon pair production close to its kinematic threshold by annihilating 45 GeV positrons with electrons in a low Z material target. In this configuration, muons are emerging from the target with a naturally low-emittance. In this paper we describe the performance of a system, to study this production mechanism, that consists in several segmented absorbers with alternating active layers composed of fast Cherenkov detectors together with a muon identification technique based on this detector. Passive layers were made of tungsten. We collected data corresponding to muon and electron beams produced at the H2 line in the North Area of the European Organization for Nuclear Research (CERN) in September 2018.

A muon collider is being proposed as a next generation facility.This collider would have unique advantages, since clean events as in electron-positron colliders are possible, and high collision energy as in hadron colliders could be reached due to negligible beam radiation losses.The beaminduced background, produced by the muon decays in the beams and subsequent interactions, reaches the interaction region and the detectors and presents unique features and challenges with respect to other machines.As an example, a diffused flux of photons and neutrons passes through the calorimeter system, which thus requires a design to avoid this substantial background.In this talk an overview of the calorimetry at the Muon Collider is given, with a particular focus on the reconstruction and measurement of hadronic jets, that are studied with the full simulation of the detector.RD for new calorimeter technologies, developed specifically for the Muon Collider, will be also presented.

Calorimeters, as other detectors, have to face the increasing performance demands of the new energy frontier experiments. For a future Muon Collider the main challenge is given by the Beam Induced Background that may pose limitations to the physics performance. However, it is possible to reduce the BIB impact by exploiting some of its characteristics by ensuring high granularity, excellent timing, longitudinal segmentation and good energy resolution. The proposed design, the Crilin calorimeter, is an alternative semi-homogeneous ECAL barrel for the Muon Collider based on Lead Fluoride Crystals (PbF2) with a surface-mount UV-extended Silicon Photomultipliers (SiPMs) readout with an optimized design for a future Muon Collider.

The High-Luminosity phase of the Large Hadron Collider at CERN (HL-LHC) poses stringent requirements on calorimeter performance in terms of resolution, pileup resilience and radiation hardness. A tungsten-CeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> sampling calorimeter is a possible option for the upgrade of current detectors. A prototype, read out with different types of wavelength-shifting fibers, has been built and exposed to high energy electrons, representative for the particle energy spectrum at HL-LHC, at the CERN SPS H4 beam line. This paper shows the performance of the prototype, mainly focussing on energy resolution and uniformity. A detailed simulation has been also developed in order to compare with data and to extrapolate to different configurations to be tested in future beam tests. Additional studies on the calorimeter and the R&D projects ongoing on the various components of the experimental setup will be also discussed.

The CMS electromagnetic calorimeter at the CERN Large Hadron Collider (LHC) has been designed to measure the energy of electrons and photons with high resolution over a wide dynamic range, using lead tungstate scintillating crystals. To minimize external noise most of the readout chain must be placed within the detector in a high radiation environment, inside the 4 T magnetic field. To cope with these demanding constraints innovative solutions have been adopted since most of the common technologies are excluded. The basic architecture and the first prototype tests of the on-detector readout chain are described.

The high antiproton-proton luminosity obtained by using a target system consisting of a hydrogen gas-jet crossing a coasting beam of cooled antiproton circulating in one of the rings of CERN's ISR provides the possibility to measure low cross section reactions with very high precision. We present measurements of the antiproton-proton elastic cross section at 90° CM at incident momenta between 3.5 GeV/c and 5.7 GeV/c. The precision of these measurements is much higher than previously reported results. The data show that the cross section of this reaction decreases faster than s−12 over this momentum range.

A tracking detector made of scintillating fibers is being developed at FNAL, for the experiment E835. The tracker will be used for the measurement of the polar angle /spl theta/, i.e. of the coordinate along the beam. The small amount of light from the fibers will be detected by solid state devices (visible light photon counters) with very high quantum efficiency. This paper reports the performance of a fiber tracker prototype, as measured at FNAL. We present results on light yield/mip, efficiency and homogeneity of response. We measured an average number of about 14 photoelectrons per mip and an efficiency higher than 99%.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>