M. Wayne

The inclusive production cross sections and mean multiplicities of π±, K±, p, and p¯ in e+e− annihilation at a c.m. energy of 29 GeV have been measured with the time-projection chamber at PEP, using ionization energy loss to separate particle types. On average, 10.7±0.6 π±, 1.35±0.13 K±, and 0.60±0.08 p,p¯ are contained in an annihilation event. The fraction of pions among final-state particles decreases from over 95% at 0.3 GeV/c momentum to about 60% at high momentum; the kaon and proton fractions rise correspondingly.Received 28 December 1983DOI:https://doi.org/10.1103/PhysRevLett.52.577©1984 American Physical Society

Results from a study of the radiation hardness of silicon photomultipliers (SiPMs) are presented. Recently developed high density (>4500 cells/mm2) SiPMs from two manufacturers (Hamamatsu (Japan) and KETEK (Germany) were exposed to 62 MeV protons at fluences up to 1×1012 protons/cm2 at the UCL (Belgium) proton cyclotron (LIF irradiation facility). The measurements were carried out for the purpose of determining radiation hardness under the extreme conditions expected at the CERN Large Hadron Collider (LHC) and SLHC. The SiPMs were biased at operating voltage during the irradiation. An increase of the SiPM's dark currents and noise was observed during and after irradiation as expected for silicon devices. The SiPM's main parameters were measured before and after irradiation. The effects of the proton radiation on breakdown voltage, signal amplitude, dark current and noise for these devices are shown and discussed.

The inclusive production cross sections and transverse momentum distributions of ${K}^{*0}$ and ${{K}_{S}}^{0}$ mesons in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at a center-of-mass energy of 29 GeV have been measured by means of the time projection chamber detector in the PEP-4 experiment. The mean multiplicites are found to be 0.49 \ifmmode\pm\else\textpm\fi{} 0.04(stat.) \ifmmode\pm\else\textpm\fi{} 0.07(syst.) (${K}^{*0}+{\stackrel{-}{K}}^{*0}$) and 1.22 \ifmmode\pm\else\textpm\fi{} 0.03(stat.) \ifmmode\pm\else\textpm\fi{}0.15(syst.) (${K}^{0}+{\stackrel{-}{K}}^{0}$) per event.

Bose-Einstein correlations between like-sign pions have been investigated in ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilation at \ensuremath{\surd}s =29 GeV using the Time Projection Chamber detector at the SLAC ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ storage ring PEP. The production rate of like-sign pion pairs with small relative momentum is found to be increased by more than 50% over the rate expected for uncorrelated production of pions. From the correlation length, a typical source radius of 0.65 fm is derived. Data are consistent with a spherical shape of the pion source. No dependence of radius or correlation strength on the event multiplicity is observed.

Two-photon production of KS0K±π∓ states has been studied by the TPC/Two-Gamma experiment at the SLAC storage ring PEP. A resonance of mass 1.42 GeV was seen when one of the photons was quite virtual but not when both photons were nearly real. Production of a spin-1 meson, which cannot be made by two real photons, would fit these observations. The Q2 dependence of the data in the resonance region agrees with this spin assignment and is incompatible with a spin-0 hypothesis. The mass and width of the resonance are similar to those of the E meson, which has been assigned JP=0− and JP=1+ by different experiments.Received 14 August 1986DOI:https://doi.org/10.1103/PhysRevLett.57.2500©1986 American Physical Society

During the last 5 years we have successfully completed R&D for the instrumentation of silicon photo multipliers (SiPMs) for the CMS HCAL Phase 1 upgrade in 2018. Much focus was put on radiation damage during these years. For the HCAL we expect a maximum total dose of 1012 n/cm2 for a total lifetime integrated luminosity of 3000 fb−1. Good correlation between cell size and performance with high radiation was found during this R&D. To evaluate the possibility of using the SiPMs in the wider CMS environment we have exposed the current state of the art smallest cell SiPMs to radiation of 6×1012 p/cm2 in 62 MeV LIF beam line in 2014 at UCL Belgium and up to 1.3×1014 p/cm2 in the CERN PS 23 GeV proton beam in late 2014. The SiPM׳s main parameters were measured before and after irradiation. Here we report on the effects of noise increase and breakdown voltage shift due to the extremely high dose.

Abstract Measurements have been made of the performance of scintillating fibers read out with visible light photon counters (VLPCs). The light yields of single-clad and multiclad scintillating fibers have been compared. The experiment consisted of 3 m long scintillating fibers of 830 μm diameter optically coupled to 8 m long waveguide fibers of 965 μm diameter read out with HISTE-IV VLPCs. For the case of multiclad scintillating fiber and waveguide, an average of 6.2 photoelectrons was detected from the far end of the scintillating fiber if the fiber end was unmirrored, and 10.2 photoelectrons if the fiber end was mirrored. With this substantial photoelectron yield, minimum-ionizing tracks can be easily detected in fiber arrays, and excellent performance characteristics are expected for the fiber trackers designed for the D0 experiment at the Fermilab Tevatron Collider and the SDC experiment at the SSC Laboratory.

The Visible Light Photon Counter (VLPC) will be used as the photodetector for a large-scale scintillating fiber tracker in the DØ upgrade. The VLPC is a solid-state device capable of high-rate single photon counting with excellent quantum efficiency, low noise and small gain dispersion. The development of the VLPC through several versions will be discussed, including the results of the characterization of more than 4278 channels of version HISTE-IV. Results of a cosmic ray test of a 3072 channel fiber tracking prototype read out with HISTE-IV VLPCs will be presented, including measurements of position resolution, tracking efficiency, and stability of VLPC performance over many months of operation. Finally, preliminary results from tests of the latest version of VLPCs and a discussion of their implementation in the DØ tracker will be given.

Results are presented on the exclusive production of four-prong final states in photon-photon collisions from the TPC/Two-Gamma detector at the SLAC ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ storage ring PEP. Measurement of dE/dx and momentum in the time-projection chamber (TPC) provides identification of the final states 2${\ensuremath{\pi}}^{+}$2${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, ${K}^{+}$${K}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, and 2${K}^{+}$2${K}^{\mathrm{\ensuremath{-}}}$. For two quasireal incident photons, both the 2${\ensuremath{\pi}}^{+}$2${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ and ${K}^{+}$${K}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ cross sections show a steep rise from threshold to a peak value, followed by a decrease at higher mass. Cross sections for the production of the final states ${\ensuremath{\rho}}^{0}$${\ensuremath{\rho}}^{0}$, ${\ensuremath{\rho}}^{0}$${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, and \ensuremath{\varphi}${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ are presented, together with upper limits for \ensuremath{\varphi}${\ensuremath{\rho}}^{0}$, \ensuremath{\varphi}\ensuremath{\varphi}, and ${K}^{\mathrm{*}0}$K\ifmmode\bar\else\textasciimacron\fi{} $^{\mathrm{*}0}$. The ${\ensuremath{\rho}}^{0}$${\ensuremath{\rho}}^{0}$ contribution dominates the four-pion cross section at low masses, but falls to nearly zero above 2 GeV. Such behavior is inconsistent with expectations from vector dominance but can be accommodated by four-quark resonance models or by t-channel factorization. Angular distributions for the part of the data dominated by ${\ensuremath{\rho}}^{0}$${\ensuremath{\rho}}^{0}$ final states are consistent with the production of ${J}^{P}$${=2}^{+}$ or ${0}^{+}$ resonances but also with isotropic (nonresonant) production. When one of the virtual photons has mass (${m}_{\ensuremath{\gamma}}^{2}$=-${Q}^{2}$\ensuremath{\ne}0), the four-pion cross section is still dominated by ${\ensuremath{\rho}}^{0}$${\ensuremath{\rho}}^{0}$ at low final-state masses ${W}_{\ensuremath{\gamma}\ensuremath{\gamma}}$ and by 2${\ensuremath{\pi}}^{+}$2${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ at higher mass. Further, the dependence of the cross section on ${Q}^{2}$ becomes increasingly flat as ${W}_{\ensuremath{\gamma}\ensuremath{\gamma}}$ increases.

We compare the particle flow in the event plane of three-jet $q\overline{q}g$ (quark-antiquark-gluon) events with the particle flow in radiative annihilation events $q\overline{q}\ensuremath{\gamma}$ (quark-antiquark-photon) for similar kinematic configurations. In the angular region between quark and antiquark jet, we find a significant decrease in particle density for $q\overline{q}g$ as compared to $q\overline{q}\ensuremath{\gamma}$. This effect is predicted in QCD as a result of destructive interference between soft-gluon radiation from quark, antiquark, and hard gluon.

The inclusive production cross section of $\ensuremath{\Lambda}$, $\overline{\ensuremath{\Lambda}}$ in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at a c.m. energy of 29 GeV has been measured with the time-projection-chamber detector at PEP. The average $\ensuremath{\Lambda}$, $\overline{\ensuremath{\Lambda}}$ multiplicity has been measured to be 0.197 \ifmmode\pm\else\textpm\fi{} 0.012(stat.) \ifmmode\pm\else\textpm\fi{}0.017(syst.). $\ensuremath{\Lambda}\ensuremath{-}\overline{\ensuremath{\Lambda}}$ pairs have been observed in jets for the first time, and the average number of $\ensuremath{\Lambda}\ensuremath{-}\overline{\ensuremath{\Lambda}}$ pairs per event has been measured to be 0.042 \ifmmode\pm\else\textpm\fi{} 0.017 \ifmmode\pm\else\textpm\fi{} 0.014.

The structure function Fγ2 for a quasireal photon has been measured in the reaction ee→eeX for Q2 in the range 0.2<Q2<7 GeV2, by use of 9200 multihadron events obtained with the TPC/Two-Gamma detector at the SLAC storage ring PEP. The data have been corrected for detector effects by a regularized unfolding procedure and are presented as Fγ2(x,Q2). The structure function shows scaling in the region 0.3<Q2<1.6 GeV2, x<0.3, and rises for higher Q2 and x>0.1. Below Q2=0.3 GeV2, scaling breaks down in accordance with the finite cross-section bound for real photons.Received 3 September 1986DOI:https://doi.org/10.1103/PhysRevLett.58.97©1987 American Physical Society

We report measurements of two-particle correlations in rapidity space between a p¯ or Λ¯ and an additional p, p¯, Λ, or Λ¯. We find evidence for local conservation of baryon number, and for the first time observe a pronounced anticorrelation between baryons with the same value of baryon number. Such an anticorrelation is expected in fragmentation models where the rapidity order of particles closely reflects their ''color order,'' as is the case, for example, in recent versions of the Lund string model.Received 14 October 1986DOI:https://doi.org/10.1103/PhysRevLett.57.3140©1986 American Physical Society

Abstract The barrel section of the novel MIP Timing Detector (MTD) will be constructed as part of the upgrade of the CMS experiment to provide a time resolution for single charged tracks in the range of 30–60 ps using LYSO:Ce crystal arrays read out with Silicon Photomultipliers (SiPMs). A major challenge for the operation of such a detector is the extremely high radiation level, of about 2 × 10 14 1 MeV(Si) Eqv. n/cm 2 , that will be integrated over a decade of operation of the High Luminosity Large Hadron Collider (HL-LHC). Silicon Photomultipliers exposed to this level of radiation have shown a strong increase in dark count rate and radiation damage effects that also impact their gain and photon detection efficiency. For this reason during operations the whole detector is cooled down to about -35°C. In this paper we illustrate an innovative and cost-effective solution to mitigate the impact of radiation damage on the timing performance of the detector, by integrating small thermo-electric coolers (TECs) on the back of the SiPM package. This additional feature, fully integrated as part of the SiPM array, enables a further decrease in operating temperature down to about -45°C. This leads to a reduction by a factor of about two in the dark count rate without requiring additional power budget, since the power required by the TEC is almost entirely offset by a decrease in the power required for the SiPM operation due to leakage current. In addition, the operation of the TECs with reversed polarity during technical stops of the accelerator can raise the temperature of the SiPMs up to 60°C (about 50°C higher than the rest of the detector), thus accelerating the annealing of radiation damage effects and partly recovering the SiPM performance.

The RADiCAL Collaboration is conducting R\&D on high performance electromagnetic (EM) calorimetry to address the challenges expected in future collider experiments under conditions of high luminosity and/or high irradiation (FCC-ee, FCC-hh and fixed target and forward physics environments). Under development is a sampling calorimeter approach, known as RADiCAL modules, based on scintillation and wavelength-shifting (WLS) technologies and photosensor, including SiPM and SiPM-like technology. The modules discussed herein consist of alternating layers of very dense (W) absorber and scintillating crystal (LYSO:Ce) plates, assembled to a depth of 25 $X_0$. The scintillation signals produced by the EM showers in the region of EM shower maximum (shower max) are transmitted to SiPM located at the upstream and downstream ends of the modules via quartz capillaries which penetrate the full length of the module. The capillaries contain DSB1 organic plastic WLS filaments positioned within the region of shower max, where the shower energy deposition is greatest, and fused with quartz rod elsewhere. The wavelength shifted light from this spatially-localized shower max region is then propagated to the photosensors. This paper presents the results of an initial measurement of the time resolution of a RADiCAL module over the energy range 25 GeV $\leq$ E $\leq$ 150 GeV using the H2 electron beam at CERN. The data indicate an energy dependence of the time resolution that follows the functional form: $\sigma_{t} = a/\sqrt{E} \oplus b$, where a = 256 $\sqrt{GeV}$~ps and b = 17.5 ps. The time resolution measured at the highest electron beam energy for which data was currently recorded (150 GeV) was found to be $\sigma_{t}$ = 27 ps.

The Do/ detector is being upgraded in preparation for the next collider run at Fermilab. The Central Fiber Tracker discussed in this report is a major component of the Do/ upgrade. The expected Tevatron luminosity of 2×1032 cm−2 sec−1, the 132ns bunch crossing time, and the Do/ detector constraints of a 2 Tesla solenoid and a 52 cm lever arm, make a scintillating fiber based tracker an optimal choice for the upgrade of the Do/ detector.

Correlations in rapidity space are presented for identified ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ and ${K}^{\ifmmode\pm\else\textpm\fi{}}$ in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at 29-GeV c.m. energy. Short-range $\mathrm{KK}$ correlations indicate local flavor compensation in the hadronization process. Long-range $\mathrm{KK}$ and $\ensuremath{\pi}\ensuremath{\pi}$ correlations prove that the initial partons carry flavor. In addition, we observe significant $K\ensuremath{\pi}$ correlations as a result of heavy-quark decays.

This paper presents results on charm photoproduction in the energy interval 40 to 160 GeV, obtained from the high-statistics charm samples of the NA 14/2 experiment at CERN. We measure the charm cross-section, the distributions inx F andp 2 and various production ratios and charge asymmetries. The total non-diffractive open-charm cross-section per nucleon is measured to be $$\sigma _{(\gamma N \to c\bar cX)} $$ at 〈E γ〉 =100 GeV. We discuss the photoproduction of charm in terms of theoretical and phenomenological models. We compare the measuredp 2 andx F distributions with first-order QCD calculations of photon-gluon fusion and obtain a value for the charm-quark mass ofm c =1.5 +0.2 −0.1 GeV/c2.

We have studied the production of prompt muons in hadronic events from ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilation at a center-of-mass energy of 29 GeV with the PEP4-TPC (Time Projection Chamber) detector. The muon p and ${p}_{t}$ distributions are well described by a combination of bottom- and charm-quark decays, with fitted semimuonic branching fractions of (15.2\ifmmode\pm\else\textpm\fi{}1.9\ifmmode\pm\else\textpm\fi{}1.2)% and (6.9\ifmmode\pm\else\textpm\fi{}1.1\ifmmode\pm\else\textpm\fi{}1.1)%, respectively. The muon spectra imply hard fragmentation functions for both b and c quarks, with 〈z(b quark)〉=0.80\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\pm\else\textpm\fi{}0.05 and 〈z(c quark)〉=0.60\ifmmode\pm\else\textpm\fi{}0.06\ifmmode\pm\else\textpm\fi{}0.04. We derive neutral-current axial-vector couplings of a(b quark)=-0.9\ifmmode\pm\else\textpm\fi{}1.1\ifmmode\pm\else\textpm\fi{}0.3 and a(c quark)=1.5\ifmmode\pm\else\textpm\fi{}1.5\ifmmode\pm\else\textpm\fi{}0.5 from the forward-backward asymmetries.

The spatial resolution and response of the segmented cathode pads of the PEP-4 TPC have been measured with data taken at 8.5 atmospheres of 80% Argon-20% Methane gas with a 4kG magnetic field. The dependence of the spatial resolution and pad response on drift distance and track-anode crossing angle is presented.

Evidence for a narrow state decaying into an F meson and a photon has been obtained in e+e− annihilation events at 29-GeV c.m. energy. This state lies 139.5 ± 8.3(stat.) ± 9.7(syst.) MeV above the F-meson mass and is consistent with the expected F* meson. The F mesons are identified by a peak in the K+K−Kπ± mass at 1.948±0.028±0.010 GeV.Received 13 September 1984DOI:https://doi.org/10.1103/PhysRevLett.53.2465©1984 American Physical Society

We present here some results obtained with the LBL Time Projection Chamber (TPC) regarding the particle identification by the measurement of the ionization losses in the relativistic rise region. This includes the method of calibration using 55Fe sources, the measurement of the resolution using cosmic rays, which shows an equivalent K-π separation of 4.8 standard deviations at 3.5 GeV/c, and the preliminary results obtained with multihadronic events from e+e- annihilations.

We use the time-projection chamber detector to study mechanisms of baryon production in the central rapidity region of jets from ${e}^{+}{e}^{\ensuremath{-}}$ annihilation. On the basis of angular correlations between protons and antiprotons, we exclude the isotropic decay of heavy mesonic clusters as a dominant source of baryons at 95% confidence level. The diquark mechanisms used in string fragmentation models reproduce the data, provided that diquarks are formed in a two-step process which allows mesons to be produced in between the baryon and antibaryon.

The upgraded DØ detector at the Tevatron collider will use about 100 000 pixels of Visible Light Photon Counters (VLPCs) readout for its scintillating fiber tracker and preshower detectors. VLPCs are solid state photodetectors that are operated at the temperature of a few degrees Kelvin, capable of detecting single photons. All VLPC chips were characterized in the presence of a 20 MHz background of photoelectrons. The acceptance rate was 87%. The operating bias ranges from 5.8 to 8.0 V, the gain from 20 000 to 60 000, and the threshold from 5 to 15 fC. All 8 pixels belonging to one chip have very similar efficiencies, thresholds and gains.

The distribution of particles in three-jet events is compared with the predictions of three fragmentation models currently in use: the Lund string model, the Webber cluster model, and an independent fragmentation model. The Lund model and, to a certain extent, the Webber model provide reasonable descriptions of the data. The independent fragmentation model does not describe the distribution of particles at large angles with respect to the jet axes. The results provide evidence that the sources of hadrons are Lorentz boosted with respect to the overall c.m.Received 22 October 1984DOI:https://doi.org/10.1103/PhysRevLett.54.270©1985 American Physical Society

We studied performances of two SiPMs before and after irradiation at the Lubljana reactor. These high density (15 μ m cell pitch size) SiPMs were developed by Hamamatsu (in cooperation with the CMS SiPM group) for the CMS HCAL Upgrade Phase I project. The S10943-4732 is a photosensor selected for the CMS HE HCAL where the SiPMs will be exposed to 2× 1011 n/cm2 (1 MeV equivalent) for the operation time of the SLHC (integrated luminosity—5000 fb−1). The HD-1015CN SiPM was developed using new Hamamatsu trench technology to reduce optical cross-talk (X-talk) between SiPM cells. Both SiPMs are considered as candidates for the CMS HCAL barrel upgrade. The SiPMs were irradiated with reactor neutrons up to 1 MeV equivalent fluence of 2× 1012 n/cm2 (that corresponds to the maximum integrated neutron fluence in the HCAL barrel for the duration of the SLHC operation).

Production of $\ensuremath{\varphi}$ mesons in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at a center-of-mass energy of 29 GeV has been observed with the time-projection chamber detector at the PEP storage ring. The $\ensuremath{\varphi}$ production rate has been measured in the energy range $0.075&lt;x&lt;0.55$ ($x=\frac{2{E}_{\ensuremath{\varphi}}}{\sqrt{s}}$), giving 0.077\ifmmode\pm\else\textpm\fi{}0.012(stat)\ifmmode\pm\else\textpm\fi{}0.016(syst) $\ensuremath{\varphi}$'s per event. The average value of ${{p}_{t}}^{2}$ relative to the thrust axis is 1.0\ifmmode\pm\else\textpm\fi{}0.4 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$.

Two-photon formation of the η' in the reaction e+e−→e+e−ηm'→e+e−π+π−γ has been studied for nearly real and virtual photons at an e+e− center-of-mass energy of 29 GeV. The γγ width of the η' is found to be 4.5±0.3(stat.)±0.7(syst.) keV. The measured dependence of this γγ width upon the photon four-momentum squared in the range 0–5 GeV2 agrees with predictions both from QCD and from ρ dominance. A spin analysis results in a strong preference for a spin-zero, relative to a spin-two, assignment for the η'. No evidence for C-parity violation is found in this η'→π+π−γ decay mode.Received 15 December 1986DOI:https://doi.org/10.1103/PhysRevD.35.2650©1987 American Physical Society

We measure an inclusive branching fraction of (13.9 ± 2.0+1.9−2.2)% for the decay τ−→ντπ−π0+nh0(n>~1), where h0 is a π0 or an η. The data sample, obtained with the time-projection-chamber detector facility at the SLAC e+e− storage ring PEP, corresponds to an integrated luminosity of 72 pb−1 at 29 GeV center-of-mass energy. The measured branching fraction is somewhat greater than the theoretical prediction and, with errors taken into account, could resolve the present difference between the inclusive and the sum of the exclusive τ± branching fractions into one charged prong.Received 1 July 1986DOI:https://doi.org/10.1103/PhysRevLett.57.1836©1986 American Physical Society

□ Leptin-deficient mice show a blunted response to hypercapnia explained by central nervous system effects. The impact of leptin on peripheral chemoreceptor function is unclear. Therefore, 9 mutant (ob/ob) and 9 wild-type ( +/+ ) mice were exposed to room air or 100% oxygen and respiratory rate (RR) and tidal volume (Vt) were measured. Subsequently, ob/ob mice received either leptin or vehicle and measurements were repeated. Compared to baseline, for +/+ mice, RR decreased significantly by 9.4% ± 3.0% (means ± SD), whereas Vt remained unchanged. Transition from normoxia to hyperoxia did not change RR and Vt in untreated ob/ob mice, whereas after leptin treatment, RR and Vt decreased significantly. Leptin deficiency abolishes the response to hyperoxia, which is restored by leptin replacement. Thus, leptin seems to be influential for a competent peripheral chemoreceptor function.

Results from a study of the radiation hardness of silicon photomultipliers (SiPMs) are presented. New ultra high density SiPMs have been recently developed by FBK for the CMS HCAL Barrel phase I upgrade. SiPMs were irradiated to a total dose of 2×1012n∕cm2 (1 MeV equivalent) at the TRIGA reactor at the JSI in Slovenia. The SiPM’s main parameters were measured before and after irradiation. The effects of the neutron radiation on breakdown voltage, signal amplitude, dark current and noise for these devices are shown and discussed.

Proton production in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at 29 GeV has been studied with the time projection chamber. Measurements of the dependence of proton fractions on momentum, transverse momentum with respect to the jet axis, hadron multiplicity, and event sphericity are reported. Our results are consistent with the assumption that primary baryons and mesons have similar production spectra, and indicate that protons provide more direct probes of underlying fragmentation phenomena than do pions.

From a study of $\ensuremath{\tau}$ decays using the Time Projection Chamber (TPC) detector at the SLAC ${e}^{+}{e}^{\ensuremath{-}}$ storage ring PEP, we have measured the one-, three-, and five-charged-particle inclusive branching fractions of the $\ensuremath{\tau}$ to be (85.2\ifmmode\pm\else\textpm\fi{}1.7)%, (14.8\ifmmode\pm\else\textpm\fi{}1.7)%, and 0.3%, respectively. Using particle identification by $\frac{\mathrm{dE}}{\mathrm{dx}}$ in the TPC we have searched for charged $K$ mesons in three-prong $\ensuremath{\tau}$ decays, and have set an upper limit on $B({\ensuremath{\tau}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{K}^{\ifmmode\pm\else\textpm\fi{}}+2 \mathrm{c}\mathrm{h}\mathrm{a}\mathrm{r}\mathrm{g}\mathrm{e}\mathrm{d}+\mathrm{n}\mathrm{e}\mathrm{u}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{l}\mathrm{s})$ of 0.6%.

Properties ofD mesons produced in the photo-production experiment NA 14/2 at CERN are reported. The following ratios of branching fractions were measured: $$\begin{gathered} Br(D^0 \to K^ + K^ - )/Br(D^0 \to K^ - \pi ^ + ) = 0.16 \pm 0.05, \hfill \\ Br(D^0 \to K^ - \pi ^ + \pi ^0 )/Br(D^0 \to K^ - \pi ^ + ) = 4.0 \pm 0.09 \pm 1.0, \hfill \\ Br(D^0 \to K^ - \pi ^ + \pi ^ + \pi ^ - )/Br(D^0 \to K^ - \pi ^ + ) \hfill \\ = 1.9 \pm 0.25 \pm 0.20 \hfill \\ \end{gathered} $$ . TheD 0→K − π + π + π − decay was analysed and the contribution of resonant subprocesses found consistent with 1ρ 0 and 0.23 $$\bar K$$ *0 per event. The angular distributions ofD 0→ $$\bar K$$ *0 showed parity violation and destructive interference betweenS- andD-waves. From a Dalitz-plot analysis of the decayD +→K − π + π + the contribution from the quasi two-body decayD +→ $$\bar K$$ *0 π + was measured to be 0.14±0.04±0.04.

A Geiger-mode electromagnetic shower calorimeter has been constructed for PEP-4. Six trapezoidal modules cover 75% of 4π solid angle in a hexagonal array. Each module contains 40 sense wire planes between 0.25 radiation-length thick lead-laminates, and is divided electrically into submodules of 27 and 13 layers. Half-degree wide hodoscopic channels in projective geometry provide excellent spatial resolution. In each gap three stereo views using the sense wires as well as strips on both cathodes at ±60° to the wires provide good shower reconstruction capabilities in multi-track jet events. Calibration and data analysis procedures are outlined. The performance of the calorimeter in the measurement of Bhabha events and the reconstruction of π0's in jet events is in excellent agreement with Monte Carlo simulations. The π0 mass resolution is MeV (rms).

Detailed measurements of the wavelength shifting fiber response to a stable and reliable light source are presented. Particulars about materials, a double reference method, and measurement technique are included. The fibers studied were several hundred Kuraray, Y-11, multiclad, 1.2-mm outer diameter wavelength shifting fibers, each cut from a reel to about one meter length. The fibers were polished, mirrored, and the mirrors were UV epoxy protected. Each fiber passed quality control requirements before installation. About 94% of the fibers tested have a response within 1% of the overall mean

Kinematic correlations between the charmed D and D mesons produced by a photon beam of mean energy 100GeVc have been measured by the NA142 experiment at CERN using a sample of almost background-free fully reconstructed DD events. The observed D and DD distributions are compared to the predictions of production models using different parameters for the charm fragmentation function and for the intrinsic transverse momentum of the partons.

In a search for heavy charge-$\frac{4}{3}e$ particles produced in ${e}^{+}{e}^{\ensuremath{-}}$ collisions at a center-of-mass energy of 29 GeV, no candidate events were found in 22 ${\mathrm{pb}}^{\ensuremath{-}1}$ of data collected by the time projection chamber at PEP. Upper limits are established on the inclusive cross section for the production of charge-$\frac{4}{3}e$ particles in the mass range of 1-10 GeV/${\mathit{c}}^{2}$.

The CERN charm photoproduction experiment NA14/2 has studied the K+K−π+, φπ+, φπ+π0, and φπ+π+π− decay modes of the Ds+ and D+ charmed mesons, and the corresponding charge conjugate states. We measure branching ratios: Br(D+→φπ+)Br(D+→K−π+π+)=0.098±0.032±0.014, Br(Ds+→K∗0K+)Br(Ds+→φπ+)=0.85±0.34±0.20, and obtain upper for the other channels. Contrary to the prediction of some theoretical models, we do noy observe any decay of Ds into φρ. Using the Lund Monte Carlo to hadronize the final-state partons we derive a value for the absolute branching fraction Br(Ds+ → φπ+) =4.8±1.9%.

The DØ preshower detector consists of scintillator strips with embedded wavelength-shifting fibers, and a readout using Visible Light Photon Counters. The response to minimum ionizing particles has been tested with cosmic-ray muons. We report results on the gain calibration and light-yield distributions. The spatial resolution is investigated taking into account the light sharing between strips, the effects of multiple scattering and various systematic uncertainties. The detection efficiency and noise contamination are also investigated.

The PEP-4 hexagonal barrel calorimeter, with lead-laminate layers and 5×lOmm2 Geiger-mode discharge cells, has demonstrated excellent stability and uniformity in operation. The use of projective geometry in half degree-wide cathode strips at ±60 degrees to the sense wire channels provides excellent spatial resolution and reconstruction capability. The electronic noise-to-signal ratio without preamplification is sufficiently low that individual 50 pC Geiger discharges are accurately measured and used for energy calibration. Measurements made at 14.5 GeV e± beam energy have provided preliminary spectra of Bhabhas and of photon-photon invariant mass. The latter show that πo's can be reconstructed.

The QuarkNet Collaboration has forged nontraditional relationships among particle physicists, high school teachers, and their students. QuarkNet centers are located at 50+ universities and labs across the United States and Puerto Rico. We provide professional development for teachers and create opportunities for teachers and students to engage in particle physics data investigations and join research teams. Students develop scientific knowledge and habits of mind by working alongside scientists to make sense of the world using authentic experimental data. Our program is based on a classroom vision where teaching strategies emulate closely the way scientists build knowledge through scientific and engineering practices. Program outcomes show that student engagement in research and masterclasses does develop an understanding of the process of scientific discovery and science. Teachers provide classroom environments that model scientific discovery and science practices and take advantage of opportunities to expand their involvement in the profession of science teaching. We describe success factors that enhance local center programs, and discuss important benefits of the program that flow on to the university faculty.

The design of the CMS phase II upgrade for the HL-LHC uses SiPMs for the Barrel Timing Layer (BTL) and the Behind HCAL detector (BH or CEH). In both sub-detectors the SiPMs will see a 1 MeV equivalent dose of around 1014 n/cm2. To lower the noise in the SiPMs the design is to keep the SiPMs at a low temperature of −30 °C. Different samples from two manufactures of SiPMs were irradiated to a total dose of resp. 2 × 1012, 5 × 1013 at the TRIGA reactor at the JSI in Slovenia. The noise in SiPMs is dominated by trap assisted tunneling which is a result of the high internal electric field in SiPMs. We therefore studied the noise behavior from ＋10 °C to −40 °C from standard high internal field and specially designed low field SiPMs from FBK-irst and Hamamatsu. After the initial characterization before annealing the noise decrease in SiPMs was also studied using accelerated annealing.

Studies have been done and continue on the design and construction of a Shashlik detector using Radiation hard quartz capillaries filled with wavelength shifting liquid to collect the scintillation light from LYSO crystals for use as a calorimeter in the Phase II CMS upgrade at CERN. The work presented here focuses on the studies of the capillaries and liquids that would best suit the purpose of the detector. Comparisons are made of various liquids, concentrations, and capillary construction techniques will be discussed.

The performance of the High-density Projection Chamber (HPC), the barrel electromagnetic calorimeter of the DELPHI experiment, is described. The detector adopts the time projection technique in order to obtain exceptionally fine spatial granularity in the three coordinates (/spl sim/2/spl times/20 mrad/sup 2/ in /spl theta//spl times//spl phi/ with nine samplings along the shower axes), using a limited number of readout channels (18432). Among the various topics concerning the HPC construction and operation, major emphasis is given to the aspects related to the calibration in energy of the calorimeter, based mainly on the analysis of the detector response to /sup 83m/Kr decays, and to the treatment of ageing in the readout proportional counters.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A large scale scintillating fiber tracker using visible light photon counter (VLPC) readout was built as a prototype far the upgraded DO central tracker. This prototype has been under test at Fermilab for six months using cosmic rays. A description of the components of the tracker including the photodetector, fibers, lightguides, ribbons, and DAQ is given. Preliminary results on detected photon yield, position resolution, efficiency and VLPC performance are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Abstract The results from a test beam experiment at Fermilab using 830 μm scintillating fibers, a version of a solid state photomultiplier, the VLPC, and a 256 channel multianode phototube are reported. Muon tracks were observed in a combined tracking system read out by VLPCs and the multianode phototube. A tracking algorithm was developed to unfold the complex cross talk pattern observed in the multianode phototube. A spatial resolution of ∼ 130 μm was obtained.

Recently developed high dynamic range Hamamatsu and FBK SiPMs were irradiated with reactor neutrons at JSI (Ljubljana) up to 2× 1014 n/cm2 (1 MeV equivalent). Parameters of the irradiated SiPMs were studied using pulsed light illumination. In this presentation we report about change in the SiPMs PDE, gain, dark current, noise and breakdown voltage after irradiation.

In 2012 the HCAL SiPM photo sensor upgrade was approved for the increased luminosity (5*1034) of SLHC. The upgrade will replace the current hybrid photodiodes (HPDs) with multi-pixel Geiger-mode avalanche photodiodes, also known as silicon photomultipliers (SiPMs). A key aspect of the upgrade to SiPMs is to add longitudinal segmentation and improve signal to noise to compensate for scintillator radiation damage. After 5 years of R&D with multiple companies we developed custom large dynamic range SiPMs with large PDE and small ENC. To ensure good mechanical alignment and easy handling of the large number of production channels (>20,000) we have developed a custom ceramic package with a very thin 0.3 mm quartz window with Kyocera. Each package holds 8 channels of SiPMs. Here we report on the final SiPM parameters of the 2014 preproduction run from Hamamatsu (HPK) who has produced a series of 175 arrays with a total of 1400 SiPMs. An overview of our QA results and measurements of the photon detection efficiency, spectral response, crosstalk and cell recovery time will be discussed.

In a search for heavy Q=23e and Q=13e particles produced in e+e− collisions at a center-of-mass energy of 29 GeV, no candidate events were found in 77 pb−1 of data collected by the time projection chamber at PEP. Upper limits are established on the inclusive cross section for the production of Q=23e and Q=13 particles in the mass range 1-13 GeV/c2, improving upon previously established limits.Received 3 April 1984DOI:https://doi.org/10.1103/PhysRevLett.52.2332©1984 American Physical Society

The DØ detector is undergoing a major upgrade to prepare for Run II with the Main Injector at the Fermilab collider. Key elements of the upgrade include a new, magnetic tracking system containing a silicon vertex detector and scintillating fiber outer tracker inside a 2 T field. The upgrades will increase the physics reach of the DØ experiment in several areas, including the study of the physics of the b-quark. In particular, simulation studies show that a measurement of sin2β can be made with an uncertainty of order 0.15, and that by fully reconstructing decays of the Bs, values of xs≤20 can be resolved.

Characterization of a large number of visible light photon counters (VLPC) is an integral part of the scintillating fiber system test for the DO upgrade, currently underway at Fermilab. We report results from our investigation of 4200 channels of HISTE IV VLPC's, for use in a cosmic ray test. We have studied the dependence of critical device characteristics like quantum efficiency, gain, and noise as a function of operating temperature and VLPC bias voltage, and the variation of these characteristics over the large sample. We also discuss the general operation of the devices and the problems encountered during the characterization.

In a photoproduction experiment using a mean photon energy of 100 GeV we have observed 29±8 Λc(Λc) charmed-baryon and antibaryon decays in the pK−π+ (pK+π−) final state. Quasi two-body final states do not contribite significantly to this channel. The mass of the Λc was measured to be 2281.7±2.7±2.6 MeV/c2 and its lifetime 0.18±0.03±0.03 ps. The ratio of ΛcD production, measured in this experiment, is significantly greater than that predicted by photon-gluon fusion and using a Lund model to describe the hadronization. This excess cannot be completely accounted for in this model, even using a Λc branching fraction in pKπ as high as 5%.

Fermilab has long had the world's most intense antiproton source. Despite this, the opportunities for medium-energy antiproton physics at Fermilab have been limited in the past and - with the antiproton source now exclusively dedicated to serving the needs of the Tevatron Collider - are currently nonexistent. The anticipated shutdown of the Tevatron in 2010 presents the opportunity for a world-leading medium-energy antiproton program. We summarize the current status of the Fermilab antiproton facility and review some physics topics for which the experiment we propose could make the world's best measurements. Among these, the ones with the clearest potential for high impact and visibility are in the area of charm mixing and CP violation. Continued running of the Antiproton Source following the shutdown of the Tevatron is thus one of the simplest ways that Fermilab can restore a degree of breadth to its future research program. The impact on the rest of the program will be minor. We request a small amount of effort over the coming months in order to assess these issues in more detail.

A 96-channel, 3-superlayer, scintillating-fiber tracking system has been tested in a 5 GeV/cπ− beam. The scintillating fibers were 830 μm in diameter, spaced 850 μm apart, and 4.3 m in length. They were coupled to 6 m long, clear fiber waveguides and finally to visible light photon counters. A spatial resolution of ∼ 150 μm for a double-layered ribbon was achieved with this tracking system. This first prototype of a charged-particle tracking system configured for the Solenoidal Detector Collaboration at the Superconducting Super Collider is a benchmark in verifying the expected number of photoelectrons from the fibers.

The performance of a large scale scintillating fiber tracker with VLPC readout has been studied in a cosmic-ray test. Approximately 9.6 photoelectrons per single layer per trigger were detected at a VLPC bias voltage of 6.5V. The doublet efficiency was nearly 100% at a 0.1% noise level and a position resolution of about 140μm was measured. We also studied the relationship between VLPC performance and VLPC bias voltage by measuring single fiber efficiency as a function of VLPC bias in the range 6.2V to 7.OV at a fixed temperature of 6.5 °K. We observed no significant variation in VLPC performance within this bias range.

A svstem of two cylindrical drift chambers has been designed and constructed to trigger the Time Projection Chamber and to assist in tracking and momentum reconstruction. Performance of these chambers has been studied with data collected from cosmic rays and actual e+e-collisions during recent experimental runs.

A large muon detection system has been constructed and is fully operational in the PEP 4 facility. It is more than 99.6% efficient. The system is rugged and reliable. It is possible to verify the integrity of all the chambers in a few minutes. Associated software for identifying muons has been written and is working.

High performance calorimetry conducted at future hadron colliders, such as the FCC-hh, poses a significant challenge for applying current detector technologies due to unprecedented beam luminosities and radiation fields. Solutions include developing scintillators that are capable of separating events at the sub-fifty picosecond level while also maintaining performance after extreme and constant neutron and ionizing radiation exposure. The RADiCAL is an approach that incorporates radiation tolerant materials in a sampling 'shashlik' style calorimeter configuration, using quartz capillaries filled with organic liquid or polymer-based wavelength shifters embedded in layers of tungsten plates and LYSO crystals. This novel design intends to address the Priority Research Directions (PRD) for calorimetry listed in the DOE Basic Research Needs (BRN) workshop for HEP Instrumentation. Here we report preliminary results from an experimental run at the Fermilab Test Beam Facility in June 2022. These tests demonstrate that the RADiCAL concept is capable of &lt; 50 ps timing resolution.

High-performance calorimetry conducted at future hadron colliders, such as the FCC-hh, poses a significant challenge for applying current detector technologies due to unprecedented beam luminosities and radiation fields. Solutions include developing scintillators that are capable of separating events at the sub-fifty picosecond level while also maintaining performance after extreme and constant neutron and ionizing radiation exposure. The radiation-hard innovative calorimeter (RADiCAL) is an approach that incorporates radiation tolerant materials in a sampling “shashlik”-style calorimeter configuration, using quartz capillaries filled with organic liquid or polymer-based wavelength shifters embedded in layers of tungsten plates and lutetium-yttrium oxyorthosilicate (LYSO) crystals. This novel design intends to address the priority research directions (PRD) for calorimetry listed in the DOE basic research needs (BRN) workshop for high energy physics (HEP) instrumentation. Here we report preliminary results from an experimental run at the Fermilab Test Beam Facility (FTBF) in June 2022. These tests demonstrate that the RADiCAL concept is capable of <50 ps timing resolution.

The barrel section of the novel MIP Timing Detector (MTD) will be constructed as part of the upgrade of the CMS experiment to provide a time resolution for single charged tracks in the range of $30-60$ ps using LYSO:Ce crystal arrays read out with Silicon Photomultipliers (SiPMs). A major challenge for the operation of such a detector is the extremely high radiation level, of about $2\times10^{14}$ 1 MeV(Si) Eqv. n/cm$^2$, that will be integrated over a decade of operation of the High Luminosity Large Hadron Collider (HL-LHC). Silicon Photomultipliers exposed to this level of radiation have shown a strong increase in dark count rate and radiation damage effects that also impact their gain and photon detection efficiency. For this reason during operations the whole detector is cooled down to about $-35^{\circ}$C. In this paper we illustrate an innovative and cost-effective solution to mitigate the impact of radiation damage on the timing performance of the detector, by integrating small thermo-electric coolers (TECs) on the back of the SiPM package. This additional feature, fully integrated as part of the SiPM array, enables a further decrease in operating temperature down to about $-45^{\circ}$C. This leads to a reduction by a factor of about two in the dark count rate without requiring additional power budget, since the power required by the TEC is almost entirely offset by a decrease in the power required for the SiPM operation due to leakage current. In addition, the operation of the TECs with reversed polarity during technical stops of the accelerator can raise the temperature of the SiPMs up to $60^{\circ}$C (about $50^{\circ}$C higher than the rest of the detector), thus accelerating the annealing of radiation damage effects and partly recovering the SiPM performance.

We report on results of a cosmic ray test of a scintillating fiber tracker using Visible Light Photon Counter (VLPC) readout. Two different detector configurations have been constructed and operated, the first with a total of 3072 channels and the second with 1,785 channels. The 3072 channel system is a prototype for the DO detector tracking upgrade and represents a configuration that is similar to that in the final detector. The second, smaller test was specifically designed to study the position resolution capabilities of the fiber tracker. A description of the cosmic ray test including trigger, fiber configuration, undoped lightguides, VLPC cassettes and cryogenics, and calibration system is given. Final results from the 3072 channel test will be presented, including measurements of resolution, light yield per minimum ionizing particle, singlet and doublet efficiency, and long-term stability. Resolution results from the second, 1785 channel test will be compared to the predicted resolution from Monte Carlo studies.

Using a high-statistics sample of more than 1000 reconstructed charmed-particle decays, the lifetimes of the weakly decaying charmed mesons and of theΛ + baryon have been measured: $$\begin{gathered} \tau _{D^ + } = 1.03 \pm 0.08 + 0.06 ps,\tau _{D^0 } = 0.417 \pm 0.018 \pm 0.015 ps \hfill \\ \tau _{D_s^ + } = 0.33_{ - 0.08}^{ + 0.12} \pm 0.03 ps,\tau _{\Lambda _c^ + } = 0.18 \pm 0.03 \pm 0.03 ps. \hfill \\ \end{gathered} $$

A search for the decay Ds+→η′π+;η′→ϱγ has been performed by the NA14/2 photoproduction experiment at CERN. A signal compatible with the Ds+ has been observed, leading to a ratio of branching fractions of Br(Ds+→η′π+)Br(Ds+→φπ+)=2.5±1.0-0.4+1.5. A value of Br(D+→η′π+)Br(D+→K−π+π+)<0.1 is set at 90% CL.

Abstract In order to fully exploit the physics opportunities of the Fermilab Tevatron in the Main Injector era, the D0 collaboration is building a major detector upgrade. All of the current D0 central and forward tracking detectors will be removed and replaced with a magnetic tracking system. Key components of this system include a silicon micro-vertex detector and a scintillating-fiber outer tracking detector surrounded by a 2 T superconducting solenoid. A preshower detector, based on scintillating tiles with fiber readout, is situated just outside the solenoid. Detailed simulations of this tracking system have been carried out. These studies show that the tracking and triggering capabilities of the upgraded tracking system will greatly enhance D0's ability to detect and study the top quark and will enable D0 to take advantage of the large amount of B physics available with the Main Injector.

The Time Projection Chamber has operated in the PEP colliding beams at SLAC since January 1982. Its signal processing system, containing 16020 channels, has been calibrated and monitored using a computer-controlled test pulser system. We describe the test system and review measurements made with the system of signal processing electronics.

We compare the pT dependence of pion, kaon and proton production cross sections in the central rapidity region in e+e− annihilation events and in proton-proton collisions at ISR energies. We find similarities both in the pT dependence of cross sections and in the particle composition as a function of pT, in agreement with the hypothesis of a universal mechanism of particle production.

We have designed, constructed, and operated a small cryostem which supports the operation of 32 channels of Visible Light Photon Counters (HISTE-IV VLPCs). The VLPCs are situated within a small enclosure which can be lowered into a 36-100 liter dewar. The enthalpy of the boil-off helium keeps the VLPCs cold, and allows the system to be operated with stability for many days within the desired temperature range of 6-7.5 K. The cryostem is instrumented with clear fiber waveguides which transport the light from an optical connector situated at the top of the cryostem and outside of the dewar to the photosensors at cryogenic temperatures within the dewar. Electrical signals from the VLPCs are amplified at room temperature using QPA02 preamplifiers. Details of design and performance are reviewed.

We report on the first search with virtual photon-photon collisions for narrow, neutral resonances with even C parity in the mass range 4.5&lt;W&lt;19 GeV. The data were obtained via the process ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\gamma}}^{\mathrm{*}}$${\ensuremath{\gamma}}^{\mathrm{*}}$\ensuremath{\rightarrow}e $^{+}e^{\mathrm{\ensuremath{-}}}$R with both the scattered ${e}^{+}$ and ${e}^{\mathrm{\ensuremath{-}}}$ detected. We find upper limits (95% confidence level) for the partial decay width of a resonance into two photons, ranging from 50 keV at W=4.5 GeV to 10 MeV at W=19 GeV. These limits constrain theoretical models involving neutral composite bosons.

We have been investigating the performance of scintillating pad detectors, individual small tiles of scintillator that are read out with wavelength-shifting fibers and visible light photon counters, for application in high luminosity colliding beam experiments such as the DO Upgrade. Such structures could provide "pixel" type readout over large fiducial volumes for tracking, preshower detection and triggering.

A calibration system for the testing of scintillating fibers and visible light photon counters (VLPC) has been constructed at Notre Dame and installed in a cosmic ray test facility at Fermilab. The purpose of the cosmic ray test is to assess the viability of the fiber tracking technique for the upgraded D0 central detector. The purpose of this calibration system is to monitor the performance of the 3072 fiber VLPC detector elements for continuity, gain and uniformity of response. Here we report on the design, construction and operation of the calibration system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Trackers based on scintillating-fiber technology are being considered by the Solenoidal Detector Collaboration at SSC and the DO collaboration at Fermilab. Some 600 fibers in the Fermilab Tevatron CO area were irradiated, thereby obtaining a hadronic irradiation at realistic rates. Four-meter-long samples of ten Bicron polystyrene-based fibre types, maintained in air, dry nitrogen, argon, and vacuum atmospheres within stainless-steel tubes, were irradiated for seven weeks at various distances from the accelerator beam pipes. Maximum doses, measured by thermoluminescence detectors, were about 80 krad. Fiber properties, particularly light yield and attenuation length, were measured over a one-year period. A description of the work together with the results is presented. At the doses achieved, corresponding to a few years of actual fiber-tracking detector operation, little degradation was observed. Recovery after several days' exposure to air was noted. Properties of unirradiated samples kept in darkness show no changes after one year.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Appears in: EDULEARN16 Proceedings Publication year: 2016Pages: 7495-7503ISBN: 978-84-608-8860-4ISSN: 2340-1117doi: 10.21125/edulearn.2016.0639Conference name: 8th International Conference on Education and New Learning TechnologiesDates: 4-6 July, 2016Location: Barcelona, Spain

We have been studying ways in which the light from several optical fibers that transmit light from scintillating tiles can be mixed and combined a single Silicon Photo Multiplier (SiPM). The purpose for mixing is to prevent a single high intensity fiber from saturating an area of the SiPM and thus causing an inaccurate reading of the overall light collected. In particular this is for use in detectors such as CMS HCAL <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1, 2</sup> where light is transmitted from scintillating tiles in 940µm fibers to a single photo-detector. If one tile has a large optical signal it can saturate an area of the SiPM and produce a signal lower than would be expected, resulting in an in-accurate energy measurement. The results of the test and the test setup will be described.

Extruded scintillator with wavelength shifting (wls) fiber for light collection and silicon avalanche photo-detection (SiPM), followed by modest amplification remains an attractive candidate for large area counters such as are required for muon detectors/tail catchers for collider detectors.We report on R & D for the optimization of such detectors which has included the development of ad hoc SiPMs and frontend electronics with 12 bit waveform digitization at 100 -200 MHz.Bias voltage is generated locally and provision is made for on board data storage and fast transfer to a local PC for immediate analysis.In addition to describing the data collection and counter assembly we will present representative data results from tests performed at the Fermilab Test Beam Facility.

A large scale scintillating fiber tracker using visible light photon counter (VLPC) readout was built as a prototype for the upgraded DO central tracker. This prototype has been under test at Fermilab for six months using cosmic rays. A description of the components of the tracker including the photodetector, fibers, lightguides, ribbons, and DAQ is given. Preliminary results indicate a mean detected yield of about 10 photoelectrons per fiber, position resolution of 140 /spl mu/m for a fiber doublet, and a doublet efficiency greater than 99%.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The QuarkNet collaboration has forged new, nontraditional relationships among particle physicists, high school teachers and their students.QuarkNet provides professional development for teachers and creates opportunities for teachers and students to engage in particle physics data investigations and join research teams.Embedded in the U.S. particle research community, QuarkNet leverages the nature of particle physics research-the long duration of the experiments with extensive lead times, construction periods, and data collection and analysis periods.QuarkNet is patterned after the large collaborations with a central management infrastructure and a distributed workload across university-and lab-based research groups.We describe the important benefits of the QuarkNet outreach program that flow to university faculty and present successful strategies that others can adapt for use in their countries.

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text Randy Ruchti and Mitchell Wayne, "Turning High Schoolers into High-Energy Physicists," Optics & Photonics News 19(11), 16-17 (2008) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Experimental applications requiring fast timing and/or high efficiency position and energy measurements typically use scintillation materials. Scintillators utilized for triggering, tracking, and calorimetry in colliding beam detectors are vulnerable to the high radiation fields associated with such experiments. We have begun an investigation of several fluorescent dyes which might lead to fast, efficient, and radiation resistant scintillators. Preliminary results of spectral analysis and efficiency are presented.

We are developing a calibration system for the Central Fiber Tracker (CFT) for the DO Upgrade to monitor the optical integrity, channel gain, and gain stability for the 76000 fiber channels with VLPC readout which comprise the system. Excitation is by blue Light Emitting Diodes (LEDs), with light distributed to the CFT fiber ribbons via luminous fiber panels. System design and performance will be presented.

A tracking detector using scintillating fibers is being developed for the D0 collaboration at Fermilab. The scintillating fibers will be coupled to clear fibers that will transport light to the photodetectors. We have developed connectors which couple the two types of fibers. The first 128-channel prototypes were machined using Delrin plastic to have v-shaped grooves. Fibers were glued into the grooves and their ends were finished with diamond fly-cut tools. Mating connectors were optically coupled by optical grease. Using a green light-emitting diode and a silicon photodiode, we measured average light transmission between 97% and 99%. Later versions of the v-groove connectors were made of acrylonitrile-butadiene-styrene plastic by injection molding.