Plastic Scintillator Hodoscope Research Articles

Development and application of CATCH: A cylindrical active tracker and calorimeter system for hyperon–proton scattering experiments

In this study, we developed a new proton detector system called CATCH, which was designed for a scattering experiment involving a Σ hyperon and a proton (J-PARC E40). CATCH is a cylindrical detector system covering an inner target that can be used to measure the trajectory and energy of a proton emitted from the target for the kinematic identification of a Σp scattering event. It comprises a cylindrical fiber tracker (CFT), a bismuth germanate (BGO) calorimeter, and a plastic scintillator hodoscope (PiID), which are coaxially arranged from the inner to the outer sides. The CFT is a tracking detector consisting of 5,000 scintillation fibers, and it has two types of cylindrical layers in which the fibers are arranged in straight and spiral configurations. 24 BGO crystals are placed around the CFT to measure the kinetic energy of the recoil proton. The PiID is used to determine whether the recoil proton is stopped in the BGO calorimeter . We performed proton–proton (pp) and proton–carbon (pC) scattering experiments using an 80 MeV proton beam to evaluate the performance of CATCH. The total energy resolution for the recoil proton was 2.8 MeV in σ for the entire angular region after the energy calibrations of the BGO calorimeter and the CFT. The angular resolution of the CFT was 1.27 degrees in σ for the proton, and the time resolution was more than 1.8 ns in σ. We also developed an analysis method for deriving the cross section of the pp scattering using CATCH. The obtained relative differential cross section for the pp elastic scattering was consistent with that obtained by reliable partial wave analysis, and the systematic error was maintained at below 10%. These performance results satisfy our requirements for a reliable detection system for the Σp scattering experiment conducted at J-PARC.

Monte-Carlo based performance assessment of ASACUSA’s antihydrogen detector

An antihydrogen detector consisting of a thin BGO disk and a surrounding plastic scintillator hodoscope has been developed. We have characterized the two-dimensional positions sensitivity of the thin BGO disk and energy deposition into the BGO was calibrated using cosmic rays by comparing experimental data with Monte-Carlo simulations. The particle tracks were defined by connecting BGO hit positions and hits on the surrounding hodoscope scintillator bars. The event rate was investigated as a function of the angles between the tracks and the energy deposition in the BGO for simulated antiproton events, and for measured and simulated cosmic ray events. Identification of the antihydrogen Monte Carlo events was performed using the energy deposited in the BGO and the particle tracks. The cosmic ray background was limited to 12 mHz with a detection efficiency of 81%. The signal-to-noise ratio was improved from 0.22 s−1∕2 obtained with the detector in 2012 to 0.26 s−1∕2 in this work.

Design and construction of the POLAR detector

The POLAR detector is a space based Gamma Ray Burst (GRB) polarimeter with a wide field of view, which covers almost half the sky. The instrument uses Compton scattering of gamma rays on a plastic scintillator hodoscope to measure the polarization of the incoming photons. The instrument has been successfully launched on board of the Chinese space laboratory Tiangong 2 on September 15, 2016. The construction of the instrument components is described in this article. Details are provided on problems encountered during the construction phase and their solutions. Initial performance of the instrument in orbit is as expected from ground tests and Monte Carlo simulation.

The FOREST detector for meson photoproduction experiments at ELPH

An electromagnetic calorimeter complex, FOREST, has been constructed for meson photoproduction experiments at the Research Center for Electron Photon Science, Tohoku University. It consists of three types of calorimeters, which are made of pure cesium-iodide crystals, lead scintillating-fiber modules, and lead glass Cherenkov counters. Each calorimeter is equipped with a plastic scintillator hodoscope to identify charged particles. The design and performance of FOREST are described. The energy responses of test calorimeters have been investigated by using 100–800MeV positron beams. The energy resolutions of the three calorimeters are found to be approximately 3%, 7%, and 5% for 1-GeV photons, respectively. A cryogenic hydrogen/deuterium target system fitted to the FOREST experiments and a newly developed data acquisition system are also presented.

Measurement of cosmic-ray muons and muon-induced neutrons in the Aberdeen Tunnel Underground Laboratory

We have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be $I_{\mu} = (5.7 \pm 0.6) \times 10^{-6}$ cm$^{-2}$s$^{-1}$sr$^{-1}$. The yield of muon-induced neutrons in the liquid scintillator was determined to be $Y_{n} = (1.19 \pm 0.08 (stat) \pm 0.21 (syst)) \times 10^{-4}$ neutrons/($\mu\cdot$g$\cdot$cm$^{-2}$). A fit to the recently measured neutron yields at different depths gave a mean muon energy dependence of $\left\langle E_{\mu} \right\rangle^{0.76 \pm 0.03}$ for liquid-scintillator targets.

Measurement of Cosmic-ray Muon-induced Spallation Neutrons in the Aberdeen Tunnel Underground Laboratory

Muon-induced neutrons are one of the major backgrounds to various underground experiments, such as dark matter searches, low-energy neutrino oscillation experiments and neutrino-less double beta-decay experiments. Previous experiments on the underground production rate of muon-induced neutrons were mostly carried out either at shallow sites or at very deep sites. The Aberdeen Tunnel experiment aims to measure the neutron production rate at a moderate depth of 611 meters water equivalent. Our apparatus comprises of six layers of plastic-scintillator hodoscopes for tracking the incident cosmic-ray muons, and 760 L of gadolinium-doped liquid-scintillator for both neutron production and detection targets. In this paper, we describe the design and the performance of the apparatus. The preliminary result on the measurement of neutron production rate is also presented.

An apparatus for studying spallation neutrons in the Aberdeen Tunnel laboratory

In this paper, we describe the design, construction and performance of an apparatus installed in the Aberdeen Tunnel laboratory in Hong Kong for studying spallation neutrons induced by cosmic-ray muons under a vertical rock overburden of 611m water equivalent (m.w.e.). The apparatus comprises six horizontal layers of plastic-scintillator hodoscopes for determining the direction and position of the incident cosmic-ray muons. Sandwiched between the hodoscope planes is a neutron detector filled with 650kg of liquid scintillator doped with about 0.06% of Gadolinium by weight for improving the efficiency of detecting the spallation neutrons. Performance of the apparatus is also presented.

A Mott polarimeter for the search of time reversal violation in the decay of free neutrons

A new polarimeter for low-energy electrons has been built and tested. The device was developed for the measurement of the transverse polarization of beta particles emitted in the decay of polarized cold neutrons. The decay electrons are identified by multi-wire proportional chambers made of low- Z materials and are detected with plastic scintillator hodoscopes. The transverse polarization is analyzed by means of large angle Mott scattering on a thin Pb foil. We describe here the elements of the apparatus and present the results of test measurements which illustrate its performance.

Development of a compact scintillator hodoscope with wavelength-shifting fibre read-out

We report on the prototyping of a plastic scintillator hodoscope with wavelength-shifting fibre read-out by a multi-anode photomultiplier as part of the development of a detector for cosmic-ray muons to be carried aboard an aircraft. Light yield and light attenuation measurements on single- and double-clad wavelength-shifting fibres were performed. Low power, low-threshold, discriminators were designed. A prototype 16-channel hodoscope with two planes was built and tested with cosmic rays. After correcting for geometrical factors a global intrinsic efficiency of ε > 98 % was obtained in both planes. The overall performance of the hodoscope proved it to be well suited for the A dler experiment to measure the high-altitude muon flux.

Design, commissioning and performance of the PIBETA detector at PSI

We describe the design, construction and performance of the PIBETA detector built for the precise measurement of the branching ratio of pion beta decay, π +→π 0e +ν e, at the Paul Scherrer Institute. The central part of the detector is a 240-module spherical pure CsI calorimeter covering ∼3 π sr solid angle. The calorimeter is supplemented with an active collimator/beam degrader system, an active segmented plastic target, a pair of low-mass cylindrical wire chambers and a 20-element cylindrical plastic scintillator hodoscope. The whole detector system is housed inside a temperature-controlled lead brick enclosure, which in turn is lined with cosmic muon plastic veto counters. Commissioning and calibration data were taken during two 3-month beam periods in 1999/2000 with π + stopping rates between 1.3·10 3 π +/ s and 1.3·10 6 π +/ s . We examine the timing, energy and angular detector resolution for photons, positrons and protons in the energy range of 5– 150 MeV , as well as the response of the detector to cosmic muons. We illustrate the detector signatures for the assorted rare pion and muon decays and their associated backgrounds.

ADC common noise correction and zero suppression in the PIBETA detector

We describe a simple procedure for reducing Analog-to-Digital Converter (ADC) common noise in modular detectors that does not require additional hardware. A method using detector noise groups should work well for modular particle detectors such as segmented electromagnetic calorimeters, plastic scintillator hodoscopes, cathode strip wire chambers, segmented active targets, and the like. We demonstrate a “second pedestal noise correction” method by comparing representative ADC pedestal spectra for various elements of the PIBETA detector before and after the applied correction.

DISTO: a large acceptance multiparticle spectrometer for 1–3 GeV proton beams

A magnetic spectrometer system has been constructed for the study of reactions with multiple charged particles in the final state, induced by polarized proton beams of few GeV energy. The system is based on a large-gap dipole magnet, with a liquid hydrogen target and scintillating fiber tracking detectors embedded inside the magnet. Multiwire proportional chambers, plastic scintillator hodoscopes, and threshold Cherenkov detectors placed outside the magnet provide additional tracking, triggering and particle identification capabilities. The system has been applied to study exclusive hyperon as well as pseudoscalar and vector meson production reactions at bombarding energies below 3 GeV. Additionally, it has been used to monitor the proton beam polarization at Laboratoire National Saturne. The components and performance of the system are reported.

A profile and flux monitor for the few GeV neutron beam at KEK

We describe a neutron beam monitor in the few GeV region developed for an experiment of the n + p → d + γ differential cross section measurement at the KEK-PS. It was used to monitor the profile and the flux of the neutron beam. The detector is a 3-plane plastic scintillator hodoscope. We present the design and performance of the monitor. The detection efficiencies evaluated with various Monte Carlo simulation codes are compared to the results of the measurements.

Method of probing inner-structure of geophysical substance with the horizontal cosmic-ray muons and possible application to volcanic eruption prediction

One potential use of cosmic-ray muons arriving nearly horizontally along the earth is a probe of the inner-structure of a gigantic geophysical substance, such as a volcanic mountain. A simple detection system comprising a plastic scintillator hodoscope which is expandable to a larger scale was developed. The first successful measurement of the inner-structure of Mt. Tsukuba is described. The future perspective of the application of the present method towards the prediction of volcanic eruption is discussed.

宇宙線ミュオンを用いた火山体トモグラフィ

One potential use of cosmic-ray muons arriving nearly horizontally along the earth is a probe of the inner-structure of a gigantic geophysical substane, such as a volcanic mountain. A simple detection system comprising a plastic scintillator hodoscope which is expandable to a larger scale was developed. The first successful measurements of the inner-structure of Mt. Tsukuba as well as Mt. Asama are described. The natural extension towards tomographic measurement is considered. The future perspective of the application of the present method towards the prediction of volcanic eruption is discussed.

The kaon spectrometer at SIS

A double-focussing QD magnetic spectrometer has been developed and installed at the SIS heavy-ion facility at GSI in Darmstadt. The spectrometer's primary purpose is to study meson production in energetic nucleus-nucleus collisions in detail. Its compact design is matched to the requirements of kaon detection with short flight path (5–6.5 m), large solid angle (up to 35 msr), wide momentum acceptance ( p max p min ⋍ 2) , maximum momentum 1.6 GeV/ c (1.9 GeV/ c at reduced solid angle) and reasonable momentum resolution (⋍ 1% without and ⋍ 10 −3 with ray tracing). A focal-plane length of about 1.5 m allows the efficient use of the detectors necessary for particle identification and ray-tracing, involving wire chambers, time-of-flight scintillators and Cherenkov detectors. Collisions can be characterized by two multiple-module plastic-scintillator hodoscopes detecting reaction fragments in the forward hemisphere. While the primary purpose for the construction of the spectrometer is the measurement of kaons, it can serve as a general purpose magnetic spectrometer. Its large solid angle also allows the study of two-particle correlations.

A scintillator hodoscope at the Tevatron collider

A plastic scintillator hodoscope for an experiment at the Fermilab Tevatron proton-antiproton collider is described. The hodoscope is used on-line to form a charged multiplicity trigger and off-line to study charged particle multiplicity distributions. The hodoscope consists of 240 counters covering the pseudorapidity range of ±3.25. It is designed to survive a radiation dose of up to 100 krad over the experiment's lifetime.

Quasi-free compton scattering by the neutron

Using non-tagged bremsstrahlung produced by a 130 MeV–20 μA c.w. electron beam of MAMI A quasi-free Compton scattering by the neutron was investigated via the 2H( γ, γ'n) 1H reaction for lab scattering angles of θ γ = 90° and 135°. The energy spectrum and angular distribution of recoiling neutrons were measured via time of flight and a plastic-scintillator hodoscope, respectively. Double-differential cross sections for quasi-free scattering by the neutron were determined on an absolute scale by normalizing to the Compton cross section of the proton. By comparing the experimental double-differential cross sections with predictions the electric polarizability of the neutron was determined, leading to α n = (10.7 −10.7 +3.3) × 10 −4 fm 3 . Thus, the upper limit of α n is further reduced as compared to our previous result, but the lower limit is still consistent with zero.

Small angle proton-proton correlations in collisions of high energy light ions with carbon and gold nuclei

Small angle correlations of protons ( p>320MeV/ c) emitted in 5.1 GeV/ c proton, 4 GeV /c deuteron and 8 GeV/ c helium-4 collisions with carbon and gold targets were measured using plastic scintillator hodoscopes and NaI(Tl) detectors placed at 72° and 101° with respect to the beam. It has been found that for both targets the two-proton correlation function depends on the emission angle and that this dependence is stronger for the carbon target than for the gold one.

Search forμ+→e+γ

This paper describes a kinematically complete search for the muon decay ${\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}{e}^{+}\ensuremath{\gamma}$. The experiment used a magnetic spectrometer outfitted with proportional chambers to measure the positron momentum vector and a large segmented NaI(T1) array to determine the $\ensuremath{\gamma}$-ray energy and impact point. The positrons were mostly from normal muon decay while the $\ensuremath{\gamma}$ rays were mostly from internal and external bremsstrahlung. Approximately 3\ifmmode\times\else\texttimes\fi{}${10}^{2}$ muons were stopped in a 50-mg/${\mathrm{cm}}^{2}$ polyethylene target. The relative timing between the positron and the $\ensuremath{\gamma}$ ray was measured with a resolution of 1.9 ns full width at half maximum (FWHM) by the use of a plastic-scintillator hodoscope for the positron and by NaI(T1) constant-fraction timing for the $\ensuremath{\gamma}$ ray. The positron energy resolution averaged over all data was 8.8% FWHM, and the $\ensuremath{\gamma}$-ray energy resolution was 8% FWHM, both at 52.8 MeV. When the $\ensuremath{\gamma}$ ray is assumed to originate at the same place in the target as the positron, the rms error in the measurement of the angle between the positron and $\ensuremath{\gamma}$-ray momentum vectors was 37 mrad. The acceptance of the apparatus for ${\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}{e}^{+}\ensuremath{\gamma}$ events was (1.75\ifmmode\pm\else\textpm\fi{}0.04)%. A maximum-likelihood analysis established a 90%-confidence upper limit for the branching ratio $\frac{\ensuremath{\Gamma}({\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}{e}^{+}\ensuremath{\gamma})}{\ensuremath{\Gamma}({\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}{e}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}})}$ of 1.7\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}10}$.