Muon Detection Efficiency Research Articles

The JUNO water Cherenkov detector system

The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton liquid scintillator detector with the primary physics goal of the neutrino mass ordering determination. The detector will be built in a laboratory 650-m underground. The pool is filled with 34 kton ultrapure water outside the central detector as a water Cherenkov detector for cosmic muon detection. 2400 MCP-PMTs detect the water Cherenkov light produced by cosmic muons. The inner surface of the water veto is covered with a Tyvek reflector to increase the light collection efficiency. A water system is used for water purification and circulation to maintain high water quality for optimal detector performance. A set of radon removal equipment will be integrated with the water system to reduce the radon-induced background in the central detector. Based on prototype studies, the radon concentration in water could be reduced to less than 10 mBq/m3. The cosmic muon detection efficiency of the water Cherenkov detector can reach 99.5%. With this veto system, the cosmic muon-induced fast neutron background can also be reduced to the level of about ∼0.1/day level.

Characterisation of Hamamatsu SiPM for cosmic muon veto detector at IICHEP

A test setup is built to characterise the SiPM and to measure muon detection efficiency of an extruded plastic scintillator detector. In the setup, light from the scintillator is readout by SiPMs using two embedded Wavelength Shifting Fibres (WLS) fibres. The SiPM was calibrated using LED source, but alternate calibration procedures using radio-active source as well as noise data were also established. The SiPM is studied at various over voltages (V ov ) and determined the operating V ov by optimising the muon detection efficiency and noise rate. The muon position along the length of the scintillator is measured using timing information from both sides of the fibres. Results from our characterisation studies of SiPM (2mm × 2mm, Model S1330-2050VE), e.g. after pulse, cross-talk, recovery time etc. will be discussed in this paper.

A feasibility study of extruded plastic scintillator embedding WLS fiber for AMoRE-II muon veto

AMoRE-II is the second phase of the Advanced Molybdenum-based Rare process Experiment aiming to search for the neutrino-less double beta decay of 100Mo isotopes using ∼200 kg of molybdenum-containing cryogenic detectors. The AMoRE-II needs to keep the background level below 10−5 counts/keV/kg/year with various methods to maximize the sensitivity. One of the methods is to have the experiment be carried out deep underground free from the cosmic ray backgrounds. The AMoRE-II will run at Yemilab with ∼1,000 m depth. However, even in such a deep underground environment, there are still survived cosmic muons, which can affect the measurement and should be excluded as much as possible. A muon veto detector is necessary to reject muon-induced particles coming to the inner detector where the molybdate cryogenic detectors are located. We have studied the possibility of using an extruded plastic scintillator and wavelength shifting fiber together with SiPM as a muon veto system. We found that the best configuration is two layers of plastic scintillators (PSs, 150 cm × 25 cm × 1.2 cm) with two WLS fibers per groove, which could separate radiogenic gammas well with muon detection efficiency above 99.4% along the length of the PS. Based on the expected flux from a prototype measurement at a 700 m deep underground, we found that the dead time of the muon veto system for AMoRE-II at the Yemilab with a 1 ms veto window is 0.6% of whole muon events.

Performance of a prototype bakelite RPC at GIF++ using self-triggered electronics for the CBM experiment at FAIR

The Muon Chamber (MuCh) is a sub-system of the Compressed Baryonic Matter (CBM) experiment for the detection of low-mass-vector mesons produced in high energy heavy ion collisions at beam energies ranging from 2 AGeV to 11 AGeV and decaying in the di-muon channel. MuCh consists of a segmented absorber and four detector triplet stations sandwiched between the absorber segments. At the 3rd and 4th stations of MuCh, Resistive Plate Chambers (RPCs) have been conceived for muon tracking. We have tested the performance of a low resistivity bakelite RPC prototype equipped with self-triggered front end electronics (MuCh-XYTER) for the CBM Muon Chamber. A systematic study on the muon detection efficiency and time resolution has been carried out in a high-rate photon background at the Gamma Irradiation Facility (GIF++) at CERN. The details of the measurement setup and the results are presented here.

Characterization of Silicon-Photomultipliers for a Cosmic Muon Veto detector

A Cosmic Muon Veto (CMV) detector using extruded scintillators is being designed around the mini-Iron Calorimeter detector at the transit campus of the India-based Neutrino Observatory, Madurai for measuring its efficiency at shallow depth underground experiments. The scintillation signal is transmitted through a Wavelength Shifting (WLS) fibre and readout by Hamamatsu Silicon-Photomultipliers (SiPMs). A Light Emitting Diode (LED) system is included on the front-end readout for in-situ calibration of the gain of each SiPM. A characterization system was developed for the measurement of gain and choice of the overvoltage (V ov) of SiPMs using the LED as well as a cosmic muon telescope. The V ov is obtained by studying the noise rate, the gain of the SiPM, and the muon detection efficiency. In case of any malfunction of the LED system during the operation, the SiPM can also be calibrated with the noise data as well as using radioactive sources. This paper describes the basic characteristics of the SiPM and the comparison of the calibration results using all three methods, as well as the V ov of the SiPMs and muon selection criteria for the veto detector.

Commissioning of the New sMDT Monitored Drift Tube Detectors for the Phase-1 Upgrade of the ATLAS Muon Spectrometer

The Muon Drift Tube (MDT) chambers provide very precise and reliable muon tracking and momentum measurement in the ATLAS muon spectrometer. Already in Run 2 of the LHC they have to cope with very high background counting rates up to 500 Hz/cm{}^{2} in the inner endcap layers. At High-Luminosity LHC (HL-LHC), the background rates are expected to increase by almost a factor of 10. New small (15 mm)-diameter Muon Drift Tube (so-called sMDT) detectors have been developed for upgrades of the muon spectrometer. They provide an order of magnitude higher rate capability and allow for the installation of additional new triplet thin-gap RPC trigger chambers in the barrel inner layer of the muon detector for HL-LHC. They have been designed for mass production at the Max Planck Institute (MPI) for Physics in Munich and achieve a sense of wire positioning accuracy of 5 mum. A pilot project for the barrel inner layer upgrade is underway during the 2019/2021 LHC shutdown. Several sMDT chambers have already been installed and operated in the ATLAS detector. The detailed studies of the muon detection efficiency and muon track resolution have been carried out after the assembling of the sMDT detectors in MPI and repeated at CERN after the integration with the new RPC detectors. The author will describe the detector design, the quality assurance and certification path, as well as will present the status of the installation and commissioning, worth its preliminary results and an overview for the complete integration of the sMDT project In the ATLAS experiment.

Triple-GEM detectors operation under gas recirculation in high-rate radiation environment

At the CERN LHC experiments, several gaseous detector technologies are operated in gas recirculation mode to lower operational costs and gas emissions. In the next years, Micro Pattern Gaseous Detector (MPGD) technologies will be largely implemented in the LHC experiments, with dedicated gas systems, and they will experience a significantly increased background radiation rate, especially in the HL-LHC phase. It is therefore fundamental to study MPGD operated with LHC gas systems, especially under gas recirculation, to be able to guarantee their safe long-term operation. In this context, the performance of Gas Electron Multiplier (GEM) detectors operated in gas recirculating systems have been studied at the CERN Gamma Irradiation Facility (GIF++), which provides an intense gamma irradiation along with a Muon beam from the SPS accelerator. Triple-GEM detectors performance has been studied in relation to operation stability during long-term high rate irradiation, as well as in terms of Muon detection efficiency with different gamma background rates. Both tests were realized with various gas mixtures and gas system conditions. A complete overview of the results obtained at the GIF++ is presented, showing the successful operation of Triple-GEM detectors during long-term high-rate irradiation and good Muon detection efficiency in LHC HL-like background radiation.

Discharge mitigation strategies for the CMS GE1/1 Triple-GEM detectors

During the next shutdowns of the LHC, three stations of the CMS muon system will be instrumented with Triple-GEM detectors. In particular, the installation of the GE1/1 station is foreseen during the Long Shutdown 2. A test installation of ten GE1/1 chambers was performed in 2016 as a proof of concept, referred to as the Slice Test. During its two years of operation, an irreversible loss in the number of efficient front-end electronics channels has been observed. This can potentially compromise the muon detection efficiency during operations of the High Luminosity LHC and will worsen the overall muon system trigger capabilities. An R&D campaign was started in June 2018, aimed to identify the source of channel loss and then ensure the safeness of the front-end electronics channels for the entire lifetime (0> 1 years) of GE1/1 detectors.

Study on the efficiency of the underground muon detectors in YangBaJing Hybrid Array

The $$\gamma $$ -ray astronomy at 100 TeV is important to unravel the puzzles related to the origin and acceleration of the Galactic cosmic rays up to PeV energy. The YangBaJing Hybrid Array (YBJ-HA), about 2% the scale of LHAASO-KM2A, is such a kind of detection instrument capable of detecting 100 TeV $$\gamma $$ -rays. And the muon detection efficiency stability of the MD array in YBJ-HA is crucial for high quality $$\gamma $$ -ray observation. To measure and monitor the muon detection efficiency, we develop a method in this work. We develop a muon bundle method to measure and monitor the efficiency of each muon detector. In this method, muon detection efficiency of the target MD unit is calculated based on the surrounding MD units and the MC simulation. The average actual muon detection efficiency of the 16 MD units is up to 83.4% during 4 years’ observation. The muon detection efficiency of each MD unit is found to be stable during 4 years’ operation. In the future, a similar method may be applicable to the muon detection efficiency study for LHAASO.

Development and characterization of single gap glass RPC

India-based Neutrino Observatory (INO) facility is going to have a 50kton magnetized Iron CALorimeter (ICAL) detector for precision measurements of neutrino oscillations using atmospheric neutrinos. The proposed ICAL detector will be a stack of magnetized iron plates (acting as target material) interleaved with glass Resistive Plate Chambers (RPCs) as the active detector elements. An RPC is a gaseous detector made up of two parallel electrode plates having high bulk resistivity like that of a float glass and bakelite. For the ICAL detector, glass is preferred over bakelite as it does not need any kind of surface treatment to achieve better surface uniformity and also the cost of associated electronics is reduced. Under the detector R&D efforts for the proposed glass RPC detector, a few glass RPCs of 1m × 1m dimension are fabricated procuring glass of ∼2mm thickness from one of the Indian glass manufacturers (Asahi). In the present paper, we report the characterization of RPC based on leakage current, muon detection efficiency and noise rate studies with varying gas compositions.

The performance of the Muon Veto of the Gerda experiment

Low background experiments need a suppression of cosmogenically induced events. The GERDA experiment located at LNGS is searching for the neutrinless double beta decay of $^{76}$Ge. It is equipped with an active muon veto the main part of which is a water Cherenkov veto with 66 PMTs in the watertank surrounding the GERDA cryostat. With this system 806 live days have been recorded, 491 days were combined muon-germanium data. A muon detection efficiency of $\varepsilon_{\mu d}=(99.935\pm0.015)$ \% was found in a Monte Carlo simulation for the muons depositing energy in the germanium detectors. By examining coincident muon-germanium events a rejection efficiency of $\varepsilon_{\mu r}=(99.2_{-0.4}^{+0.3})$ \% was found. Without veto condition the muons by themselves would cause a background index of $\textrm{BI}_{\mu}=(3.16 \pm 0.85)\times10^{-3}$ cts/(keV$\cdot$kg$\cdot$yr) at $Q_{\beta\beta}$.

A plastic scintillator-based muon tomography system with an integrated muon spectrometer

A muon scattering tomography system which uses extruded plastic scintillator bars for muon tracking and a dedicated muon spectrometer that measures scattering through steel slabs has been constructed and successfully tested. The atmospheric muon detection efficiency is measured to be 97% per plane on average and the average intrinsic hit resolution is 2.5mm. In addition to creating a variety of three-dimensional images of objects of interest, a quantitative study has been carried out to investigate the impact of including muon momentum measurements when attempting to detect high-density, high-Z material. As expected, the addition of momentum information improves the performance of the system. For a fixed data-taking time of 60s and a fixed false positive fraction, the probability to detect a target increases when momentum information is used. This is the first demonstration of the use of muon momentum information from dedicated spectrometer measurements in muon scattering tomography.

High-rate performance of the MWPCs for the LHCb muon system

The high-rate performance of a multiwire proportional chamber of the LHCb muon detector was tested. The chamber, equipped with the final front-end electronics, was tested using a ∼ 100 GeV muon beam superimposed on a 662 keV γ flux of variable intensity produced by the 137Cs radioactive source of the CERN Gamma Irradiation Facility (GIF). No significant variation in the muon detection efficiency or in the time response of the chamber was observed at the highest gamma rate.

A Plane Parallel Chamber Used as a Stopped Muon Detector for the Active Target of the FAMILON Project

The performance characteristics of a plane parallel chamber were investigated on beams of slow muons and positrons, as well as on an electron beam from a 106Ru β source. The chamber was filled with CO2 or a gas mixture of Ar (30%) + CO2(70%) at atmospheric pressure. The amplitude spectra of charged particles and the efficiency of their detection were measured. The muon and positron momenta were ∼27 MeV/c. It was shown that the muon detection efficiency of the plane parallel chamber with a 1-mm gas gap and CO2 (100%) used as a working gas was as high as 99%, while that of the chamber with a 0.4-mm gas gap and a working gas mixture of Ar(30%) + CO2(70%) was 88%. This result, along with the detector's high response speed, allows the plane parallel chamber to be used as an active target being developed for a future experiment (FAMILON) on searching for neutrinoless muon decay with the release of a scalar Goldstone's boson (µ → eα).

Muon identification in the Belle experiment at KEKB

This paper describes the muon identification method and its performance in the Belle experiment at KEKB. Muon and hadron likelihood are calculated for each track using its range and transverse scattering in the KL-and-muon detector (KLM). We apply a cut on the normalized muon likelihood Lμ to identify the track as a muon. Above the detection threshold of 0.6GeV/c, the measured muon detection efficiency and pion fake rate are approximately constant for momenta greater than 1.0 and 1.5GeV/c, respectively. Between 1.0 and 3.0GeV/c, the averaged muon detection efficiency is 89% and the pion fake rate per track is 1.4% over the KLM acceptance, using the standard selection criterion Lμ>0.9.

Performance test of a micro-pattern stereo detector with two gas electron multipliers

We report on the performance of a large micro-pattern detector with two gas electron multiplier foils and a two-layer readout structure at ground potential. The two readout layers each have a 406 μm pitch and cross at an effective angle of 6.7°. This structure allows for two orthogonal coordinates to be determined. Using a muon beam at CERN together with a silicon tracking system, the position resolutions of the two coordinates are measured to be 50 μm and 1 mm respectively (1 standard deviation). The muon detection efficiency for the two-dimensional space points reaches 96%. The detector was found to be well operational over a wide range in the settings of the different electrical fields.

Construction and performance of a micro-pattern stereo detector with two gas electron multipliers

The construction of a micro-pattern gas detector of dimensions 40×10 cm 2 is described. Two gas electron multiplier foils (GEM) provide the internal amplification stages. A two-layer readout structure was used, manufactured using the same technology as the GEM foils. The strips of each layer cross at an effective crossing angle of 6.7° and have a 406 μm pitch. The performance of the detector has been evaluated in a muon beam at CERN using a silicon telescope as reference system. The position resolutions of two orthogonal coordinates are measured to be 50 μm and 1 mm , respectively. The muon detection efficiency for two-dimensional space points reaches 96%.

Theoretical estimate of multimuon events μ + Fe → multimuons + x

We estimate the production of charmed particles in the μ-iron Fermilab experiment at 150 GeV/ c using the ψ vector dominance. In order to derive the leptonic branching ratio of charmed paticles B μ from multimuon events, we compute the muon detection efficiency which depends on the shape of the charmed particle momentum distribution and which turns out to be low (⋍0.15 to 0.25) . We obtain a good fit of the kinematical features of the multimuon events. A leptonic branching ratio of a few percent (≲4%) is compatible with the number of dimuons but the predicted number of trimuons is too low. Due to the very limited statistics, no firm conclusions can yet be drawn.