Scintillator Tiles Research Articles

Tests of Scintillator Tiles for the Technological Prototype of Highly Granular Hadron Calorimeter

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SiPM photosensors and fast timing readout for the Barrel Time-of-Flight detector in P̄ANDA

The Barrel Time-of-Flight detector system will be installed in the upcoming P̄ANDA experiment at FAIR in Germany. The detector has a barrel shape of ϕ=0.5 m and 1.8 m long, covering about 5 m2, which corresponds to the laboratory polar angle coverage of 22̂<θ<140̂. The detector is a scintillation tile hodoscope. A single scintillation tile segment has a dimension of 90× 30 mm2 and 5 mm thickness, and photons are detected by Silicon Photomultipliers at both ends. 4 Silicon Photomultipliers are combined to work as a single sensor in order to increase the sensitive area and to improve the timing performance. In total, the system consists of 1920 scintillator tiles, 3840 readout channels, and makes use of 15360 Silicon Photomultiplier sensors. In this paper, the requirement, design and the result of an actual performance test of the P̄ANDA Barrel Time-of-Flight detector are presented. The test shows that the current design fulfils satisfactorily the required timing performance (σt∼ 56 ps) and the timing performance depends little on the hit position on the surface.

Brightness and uniformity measurements of plastic scintillator tiles at the CERN H2 test beam

We study the light output, light collection efficiency and signal timing of a variety of organic scintillators that are being considered for the upgrade of the hadronic calorimeter of the CMS detector. The experimental data are collected at the H2 test-beam area at CERN, using a 150 GeV muon beam. In particular, we investigate the usage of over-doped and green-emitting plastic scintillators, two solutions that have not been extensively considered. We present a study of the energy distribution in plastic-scintillator tiles, the hit efficiency as a function of the hit position, and a study of the signal timing for blue and green scintillators.

The P̄ANDA Barrel-TOF Detector

The P̄ANDA experiment is a fixed target experiment in which antiprotons collide with stationary hydrogen atoms. The main physics program of the experiment is to study open questions in hadron physics by performing charmonium spectroscopy and precisely measuring the width, mass and decay branches, and investigating possible exotic states like glueballs and hybrids. The Barrel Time-of-Flight detector (Barrel TOF), located between the DIRC detector and the electromagnetic calorimeter (EMC), which is built in the P̄ANDA target spectrometer, has been designed to measure the time at which a charged particle transits the detector with a resolution superior to the other sub-detectors of P̄ANDA. A time resolution below 100 ps (sigma) is mandatory for this sub-detector to fulfil the requirements of good event separation and particle identification below the Cherenkov threshold. The implementation of the Barrel TOF is based on very fast organic scintillator tiles with a size of 87 x 29.5 x 5 mm3 coupled to Silicon Photomultipliers. The total of 1920 tiles are read out by 8 SiPMs each and cover almost the full azimuthal range and polar angles from 22.5∘ to 140∘ and an area of about 5 m2. The current prototypes achieve ∼60 ps, well below the design goal. The detector R&D is now in a matured stage.

Comparison of Energy Reconstruction Schemes and Different Granularities in the CALICE Scintillator-Steel Analogue Hadron Calorimeter

The CALICE collaboration develops different high-granularity hadronic calorimeter technologies for a future linear collider. These technologies differ in active material, granularity and their readout and thus their energy reconstruction schemes. The Analogue Hadron Calorimeter (AHCAL), based on scintillator tiles with Silicon Photomultiplier readout, measures the signal amplitude of the energy deposition in cells of at most 3 × 3 cm2 size. The Digital, Resistive Plate Chamber (RPC) based, HCAL (DHCAL) detects hits above a certain threshold by firing pad sensors of 1 × 1 cm2. A 2 bit readout is provided by the, also RPC based, Semi-Digital HCAL (SDHCAL), which counts hits above three different thresholds per 1 × 1 cm2 cell. All three calorimeter concepts have been realised in a 1m3 prototype with interleaved Steel absorber and tested at various test beams. This study investigates the impact of the readout, granularity and active medium on the energy resolution individually by applying the reconstruction procedures on AHCAL data, that can also be processed in a way which emulates a (semi-) digital readout system. The difference in granularity is studied via simulations of an AHCAL with 1 × 1 cm2 cell sizes.Additionally, a so-called Software Compensation algorithm is developed to weight hits dependent on their energy content and correct for the difference in the response to the electromagnetic and hadronic sub-showers and thus reduce the influence of fluctuations in the π0 generation. The impact on the energy resolution will be discussed and compared to the other energy reconstruction schemes.

The upgraded calibration system for the scintillator-PMT tile hadronic calorimeter of the ATLAS experiment at CERN/LHC

The TileCal section of the hadronic calorimeter of the ATLAS detector at the Large Hadron Collider (LHC), CERN, is a sampling calorimeter employing steel plates as absorber and plastic scintillator tiles read out by photomultiplier tubes (PMTs) as the active medium. We present an overview of the calibration system that enables the TileCal to meet its design goals of sub-1% level accuracy as well as excellent short- and long-term stability through constant monitoring.

The P̄ANDA Barrel-TOF Detector at FAIR

The barrel-Time-of-Flight subdetector is one of the outer layers of the multi-layer design of the \\panda target spectrometer. It is designed with a minimal material budget in mind mainly consisting of 90×30×5 mm3 thin plastic scintillator tiles read out on each end by a serial connection of 4 SiPMs. 120 such tiles are placed on 16 2460 × 180 mm2 PCB boards forming a barrel covering an azimuthal angle from 22.5̂ to 150̂. The detector is designed to achieve a time resolution below σ< 100 ps which allows to distinguish events in the constant stream of hits, as well as particle identification below the Cherenkov threshold via the time-of-flight; simultaneously providing the interaction times of events. The current prototype achieved a time resolution of ∼54 ps, well below the design goal.

Performance of the ATLAS Tile Calorimeter

The Tile Calorimeter (TileCal) is the central scintillator-steel sampling hadronic calorimeter of the ATLAS experiment at the LHC . Jointly with other calorimeters it is designed for energy reconstruction of hadrons, jets, tau-particles and missing transverse energy. The scintillation light produced in the scintillator tiles is transmitted by wavelength shifting fibers to photomultiplier tubes (PMTs). The analog signals from the PMTs are amplified, shaped and digitized by sampling the signal every 25 ns. The TileCal frontend electronics reads out the signals produced by about 10000 channels measuring energies ranging from ∼30 MeV to ∼2 TeV . Each stage of the signal production from scintillation light to the signal reconstruction is monitored and calibrated. The performance of the calorimeter has been established with cosmic ray muons and the large sample of the proton-proton collisions. The response of high momentum isolated muons is used to study the energy response at the electromagnetic scale, isolated hadrons are used as a probe of the hadronic response and its modelling by the Monte Carlo simulations. The calorimeter time resolution is studied with multijet events. Results on the calorimeter operation and performance are presented, including the calibration, stability, absolute energy scale, uniformity and time resolution. These results show that the TileCal performance is within the design requirements and has given essential contribution to reconstructed objects and physics results.

The Mu3e Experiment

The Mu3e experiment will search for lepton flavor violation in the neutrinoless muon decay μ+→e+e−e+ with a sensitivity down to 10−16 (90% C.L.) using the world most intense muon beam at the Paul Scherrer Institute. The μ+→e+e−e+ decay is strongly suppressed in the Standard Model whilst several Beyond the SM models predict observable effects accessible to the new generation of LFV experiments. The search for the μ+→e+e−e+ decay requires a large acceptance detector capable of measuring up to 2 × 109 decays of stopped muons per second with excellent momentum, space, and time resolution to suppress backgrounds below the 1016 level. The required Mu3e detector performance is possible thanks to tracking detectors based on thin monolithic active silicon pixel sensors (HV-MAPS) and very precise timing measurements using scintillating fibers and tiles both coupled to silicon photo-multipliers. The first phase of the Mu3e experiment has been recently approved. Following an intense R&D program the construction of the detector is about to start. First data taking is expected in 2019.

Sensors for the CMS High Granularity Calorimeter

The CMS experiment is currently developing high granularity calorimeter endcaps for its HL-LHC upgrade. The design foresees silicon sensors as the active material for the high radiation region in the electromagnetic section and the forward region of the hadronic part. Regions of lower radiation are equipped with plastic scintillator tiles. This technology is similar to the calorimeter prototypes developed in the framework of the Linear Collider by the CALICE collaboration. The current status of the silicon sensor development is presented. Results of single diode measurements are shown as well as tests of full 6-inch hexagonal sensor wafers. A short summary of test beam results concludes the report.

Status of the Mu3e detector

Mu3e is an experiment searching for charged lepton flavour violation in the decay μ+ → e+e−e+. Decay vertex position, decay time and particle momenta have to be precisely measured in order to reject both accidental and physics background. A silicon pixel tracker based on 50 μm thin High-Voltage Monolithic Active Pixel Sensors (HV-MAPS) in a 1 T magnetic field provides precise vertex and momentum information. A scintillating fibre detector and a scintillating tile detector provide sub-nanosecond time information. The status of the Mu3e detector is presented, summarizing the development of HV-MAPS chips, the pixel detector modules as well as the timing detectors.

Geant4 simulation of optical photon transport in scintillator tile with direct readout by silicon photomultiplier

The direct coupling of silicon photomultiplier to the scintillator tile is considered to be the main option for active elements of the highly granular hadron calorimeter developed for future linear collider experiments. In this study, the response of the scintillator-SiPM system to minimum ionising particles was simulated using the optical photon transport functionality available in the Geant4 package. The uniformity of response for both flat tile and tile with dimple was estimated from the simulations and compared to the experimental results obtained in the previous studies.

MuTRiG: a mixed signal Silicon Photomultiplier readout ASIC with high timing resolution and gigabit data link

MuTRiG is a mixed signal Silicon Photomultiplier readout ASIC designed in UMC 180 nm CMOS technology for precise timing and high event rate applications in high energy physics experiments and medical imaging. It is dedicated to the readout of the scintillating fiber detector and the scintillating tile detector of the Mu3e experiment. The MuTRiG chip extends the excellent timing performance of the STiCv3 chip with a fast digital readout for high rate applications. The high timing performance of the fully differential SiPM readout channels and 50 ps time binning TDCs are complemented by an upgraded digital readout logic and a 1.28 Gbps LVDS serial data link. The design of the chip and the characterization results of the analog front-end, TDC and the LVDS data link are presented.

Liquid scintillator tiles for calorimetry

Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. The light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity, and some preliminary results on radiation hardness.

SPHENIX Calorimeter Design and Jet Performance

The PHENIX collaboration is planning a detector upgrade, sPHENIX, which consists of large acceptance calorimetry and tracking detectors built around the superconducting solenoid recently shipped to Brookhaven from the decommissioned BaBar experiment at SLAC. The sPHENIX calorimeter system includes three radial layers of sampling calorimeters, a tungsten-scintillating fiber electromagnetic calorimeter, and two longitudinally segmented sampling hadron calorimeters that are made of scintillator tiles and steel plates. Together, they provide hermetic coverage in |η|<1 for calorimetry based jet measurements as well as minimal bias jet trigger capability, which coupled with high resolution tracking, enable an extremely rich jet physics program at RHIC.

Optimization of the light yield properties from scintillator tiles read out directly by silicon photomultipliers

The research of the light yield from the scintillator tiles with direct readout by silicon photomultipliers (SiPM) has been performed. The tile size is 30 x 30 x 3 mm3 as planned for the AHCAL of the ILD at the ILC. The different tile geometries were studied. The uniformity of light yield has been optimized and one geometry has been selected. The results are compared to the studies on the same topic, performed by another groups.

Highly granular hadron calorimeter: software compensation and shower decomposition

The highly granular analogue hadron calorimeter was developed and constructed by the CALICE collaboration. The active layers of the calorimeter are assembled from scintillator tiles with individual readout by silicon photomultipliers and are interleaved with absorber plates. The response and resolution of the calorimeter equipped with steel absorber was intensively tested in single particle beams. The application of software compensation techniques developed for the scintillator-steel prototype allows for reduction of the stochastic term of the single particle resolution from 58%/ √E/GeV to 45%/ √E/GeV. The detailed study and decomposition of the longitudinal and radial profiles of hadron-induced showers in the energy range from 10 to 80 GeV are presented and compared to GEANT4 simulations.

Efficiency and timing resolution of scintillator tiles read out with silicon photomultipliers

Silicon photomultipliers (SiPM) are semiconductor photo sensors that have the potential to replace photomultiplier tubes (PMT) in various fields of application. We present detectors consisting of 30 × 30 × 0.5 cm3 fast plastic scintillator tiles read out with SiPMs. The detectors offer great electronic and mechanical advantages over the classical PMT-scintillator combination. SiPMs are very compact devices that run independent of magnetic fields at low voltages and no light guides between the scintillator and the SiPM are necessary in the presented layouts. Three prototypes, two of which with integrated wavelength shifting fibres, have been tested in a proton beam at the COSY accelerator at Forschungszentrum Jülich. The different layouts are compared in terms of most probable pulse height, detection efficiency and noise behaviour as well as timing resolution. The spatial distributions of these properties across the scintillator surface are presented. The best layout can be operated at a mean efficiency of ϵ̄=99.9 % while sustaining low noise rates in the order of 10 Hz with a timing resolution of less than 3 ns. Both efficiency and timing resolution show good spatial homogeneity.

Barrel time-of-flight detector for the PANDA experiment at FAIR

The barrel time-of-flight detector for the PANDA experiment at FAIR is foreseen as a Scintillator Tile (SciTil) Hodoscope based on several thousand small plastic scintillator tiles read-out with directly attached Silicon Photomultipliers (SiPMs). The main tasks of the system are an accurate determination of the time origin of particle tracks to avoid event mixing at high collision rates, relative time-of-flight measurements as well as particle identification in the low momentum regime. The main requirements are the use of a minimum material amount and a time resolution of σ<100ps. We have performed extensive optimization studies and prototype tests to prove the feasibility of the SciTil design and finalize the R&D phase. In a 2.7GeV/c proton beam at Forschungszentrum Jülich a time resolution of about 80ps has been achieved using SiPMs from KETEK and Hamamatsu with an active area of 3×3mm2. Employing the Digital Photon Counter from Philips a time resolution of about 30ps has been reached.

Scintillator tiles read out with silicon photomultipliers

A detector prototype based on a fast plastic scintillator read out with silicon photomultipliers is presented. All studies have been done with cosmic muons and focus on parameter optimization such as coupling the SiPM to the scintillator or wrapping the scintillator with reflective material. The prototype shows excellent results regarding the light-yield and offers a detection efficiency of 99.5% with a signal purity of 99.9% for cosmic muons.