Identification Detector Research Articles

Latest results from the TORCH R&D Project

TORCH (Timing Of internally Reflected CHerenkov photons) is a precision time-of-flight detector for particle identification at low momentum. It uses Cherenkov photons produced by charged particles passing through a quartz radiator plate. Some of these photons propagate by total internal reflection, they emerge at the edges and are subsequently focused onto photon detectors. The recorded positions and arrival times of the photons are used to precisely reconstruct their trajectory and propagation time in the quartz. This allows to determine the crossing time of the particles through the plate. The TORCH design requires the development of fast photon detectors with fine and asymmetric anode segmentation. The overall per-photon time precision must be better than 70 ps after signal processing and photon path reconstruction in the quartz. In addition, the photon detectors must survive several years of high illumination levels. The on-going R&D programme aims at demonstrating the TORCH basic concept through the realization of a detector module equipped with custom photon detectors featuring the required granularity and lifetime, with dedicated fast front-end electronics and with high-quality quartz radiator and focussing optics. This paper will report on the latest TORCH results achieved in the laboratory and in charged particle beam tests. It will also introduce the developments towards a full-scale module prototype.

Data management and database framework for the MICE experiment

The international Muon Ionization Cooling Experiment (MICE) currently operating at the Rutherford Appleton Laboratory in the UK, is designed to demonstrate the principle of muon ionization cooling for application to a future Neutrino Factory or Muon Collider. We present the status of the framework for the movement and curation of both raw and reconstructed data. A raw data-mover has been designed to safely upload data files onto permanent tape storage as soon as they have been written out. The process has been automated, and checks have been built in to ensure the integrity of data at every stage of the transfer. The data processing framework has been recently redesigned in order to provide fast turnaround of reconstructed data for analysis. The automated reconstruction is performed on a dedicated machine in the MICE control room and any reprocessing is done at Tier-2 Grid sites. In conjunction with this redesign, a new reconstructed-data-mover has been designed and implemented. We also review the implementation of a robust database system that has been designed for MICE. The processing of data, whether raw or Monte Carlo, requires accurate knowledge of the experimental conditions. MICE has several complex elements ranging from beamline magnets to particle identification detectors to superconducting magnets. A Configuration Database, which contains information about the experimental conditions (magnet currents, absorber material, detector calibrations, etc.) at any given time has been developed to ensure accurate and reproducible simulation and reconstruction. A fully replicated, hot-standby database system has been implemented with a firewall-protected read-write master running in the control room, and a read-only slave running at a different location. The actual database is hidden from end users by a Web Service layer, which provides platform and programming language-independent access to the data.

NeutronSTARS: A segmented neutron and charged particle detector for low-energy reaction studies

NeutronSTARS (Neutron-S ilicon T elescope A rray for R eaction S tudies) consists of 2.2-tons of gadolinium-doped liquid scintillator for neutron detection and large area silicon detectors for charged particle identification. This detector array is intended for low-energy-nuclear-reaction measurements that result in the emission of neutrons such as (n,xn) and fission. This paper describes the NeutronSTARS experimental setup, calibration, and the array’s response to neutral and charged particles.

Electronic readout system for the Belle II imaging Time-Of-Propagation detector

The imaging Time-Of-Propagation (iTOP) detector, constructed for the Belle II experiment at the SuperKEKB e+e− collider, is an 8192-channel high precision Cherenkov particle identification detector with timing resolution below 50 ps. To acquire data from the iTOP, a novel front-end electronic readout system was designed, built, and integrated. Switched-capacitor array application-specific integrated circuits are used to sample analog signals. Triggering, digitization, readout, and data transfer are controlled by Xilinx Zynq-7000 system on a chip devices.

TPC status for MPD experiment of NICA project

In a frame of the JINR scientific program on study of hot and dense baryonic matter a new accelerator complex Ion Collider fAcility (NICA) based on the Nuclotron-M is under realization. It will operate at luminosity up to 1027 cm−2s−1 for Au79+ ions. Two interaction points are foreseen at NICA for two detectors which will operate simultaneously. One of these detectors, the Multi-Purpose Detector (MPD), is optimized for investigations of heavy-ion collisions. The Time-Projection Chamber (TPC) is the main tracking detector of the MPD central barrel. It is a well-known detector for 3-dimensional tracking and particle identification for high multiplicity events. The conceptual layout of MPD and detailed description of the design and main working parameters of TPC, the readout system based on MWPC and readout electronics as well as the TPC subsystems and tooling for assembling and integration TPC into MPD are presented.

The TORCH detector R&D: Status and perspectives

TORCH (Timing Of internally Reflected CHerenkov photons) is a time-of-flight detector for particle identification at low momentum. It has been originally proposed for the LHCb experiment upgrade. TORCH is using plates of quartz radiator in a modular design. A fraction of the Cherenkov photons produced by charged particles passing through this radiator propagate by total internal reflection, they emerge at the edges and are subsequently focused onto fast, position-sensitive single-photon detectors. The recorded position and arrival time of the photons are used to precisely reconstruct their trajectory and propagation time in the quartz. The on-going R&D programme aims at demonstrating the TORCH basic concept through the realization of a full detector module and has been organized on the following main development lines: micro-channel plate photon detectors featuring the required granularity and lifetime, dedicated fast front-end electronics preserving the picosecond timing information provided by single photons, and high-quality quartz radiator and focussing optics minimizing photon losses. The present paper reports on the TORCH results successfully achieved in the laboratory and in charged particle beam tests. It will also introduce the latest developments towards a final full-scale module prototype.

The High Momentum Particle IDentification (HMPID) detector PID performance and its contribution to the ALICE physics program

The ALICE apparatus is dedicated to study the properties of strongly interacting matter under extremely high temperature and energy density conditions. For this, enhanced particle identification (PID) capabilities are required. Among the PID ALICE detectors, the ALICE-HMPID (High Momentum Particle IDentification) detector is devoted to the identification of charged hadrons, exploiting the Cherenkov effect. It consists of seven identical RICH modules, with liquid C6F14 as Cherenkov radiator (n ≈1.298 at λ=175nm). Photon and charged particle detection is performed by a MWPC, coupled with a pad segmented CsI coated photo-cathode. The total CsI active area is 10.3m2. The HMPID provides 3 sigma separation for pions and kaons up to pT=3GeV/c and for kaons and (anti-)protons up to pT=5GeV/c. A review of the HMPID PID performance, in particular in the challenging central Pb–Pb collisions, and its contribution to the ALICE physics program, using the LHC RUN1 (2010–2013) and RUN2 (2015) data, are presented.

Conception and design of a control and monitoring system for the mirror alignment of the CBM RICH detector

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Anti-proton and Ion Research (FAIR) will investigate the phase diagram of strongly interacting matter at high net-baryon density and moderate temperature in A+A collisions. One of the key detectors of CBM to explore this physics program is a Ring Imaging CHerenkov (RICH) detector for electron identification. For a high performance of the RICH detector precise mirror alignment is essential. A three-step correction cycle has been developed, which will be discussed: First a qualitative, fast check of the mirror positions, second a quantitative determination of possible misalignments and third a software correction routine, allowing a proper functioning of the RICH under misalignment conditions.

The TORCH time-of-flight detector for particle identification and photon vertex association

TORCH (Time Of internally Reflected CHerenkov light) is a novel time-of-flight detector, designed to provide π /K/p particle identification up to 0∼ 1 GeV/c momentum and beyond. To achieve this, a time resolution of ∼ 15 ps combining information from 0∼ 3 detected photons is required over a 10 m flight path. Large areas can be covered with TORCH, nominally up to 30 m2. One such application is for the LHCb experiment, to complement the particle identification capabilities of its RICH detectors. TORCH has a DIRC-like construction with 10 mm-thick synthetic amorphous fused-silica plates as a radiator. Cherenkov photons propagate by total internal reflection to the plate edges and there are focussed onto an array of position-sensitive photodetectors. Custom-built micro-channel plate photo-multipliers (MCP-PMTs) are being developed in collaboration with industry to provide the lifetime, granularity and time resolution to meet the TORCH specifications. In the present paper, laboratory tests of the MCP-PMTs developed for TORCH and its readout electronics are presented. Test beam measurements of a prototype TORCH detector in a low-momentum mixed beam of pions and protons are highlighted. Time resolutions for individual photons approaching 100 ps is achieved, after correction for dispersion effects in the quartz medium. In addition to the particle identification capabilities, the high-precision timing information that TORCH provides could be used at the high-luminosity LHC to associate high-energy photons with the correct primary interaction vertex amongst the many expected.

Performance of the High Momentum Particle IDentification detector of ALICE during the LHC run period 2015–2016

In the period June 2015–September 2016 the LHC has delivered pp and Pb-Pb collisions respectively at √s=13TeV and √sNN=5.02TeV for a total integrated luminosity in ALICE of 14pb−1. The High Momentum Particle IDentification detector (HMPID) is part of the ALICE experiment. It is based on seven Ring Imaging Cherenkov (RICH) modules, 1.3×1.3m2 each, with a proximity focusing geometry. The Cherenkov photon detection is achieved by pad segmented photocathodes, coated with 300nm thick Caesium Iodide layer, installed in multiwire proportional chambers. Liquid C6F14 (perfluorohexane) with n=1.2989 at λ=175nm is used as Cherenkov radiator. The HMPID identifies with three sigma separation charged π and K in the momentum range 1–3GeV/c and protons in the range 1.5–5GeV/c. The scatter plots of the Cherenkov angle for both pp and Pb-Pb events are presented as preliminary Particle Identification (PID) performance. After the good results shown during 2010–2013, in this paper the HMPID performance in the period 2015–2016, with emphasis on the CsI quantum efficiency stability, are presented. Finally the perspectives of the detector operation in the period HL-LHC 2019–2022, are briefly discussed.

The laser calibration system of the TOP detector

The TOP detector of the Belle II Experiment at KEK is a particle identification detector, devoted mainly to the separation of charged pions and kaons. The Cherenkov photons produced in fused silica bars are detected by an array of micro-cannel plate photomultipliers, and the position and time of arrival of the photoelectrons are used to identify the particle. In order to achieve a time resolution of less than 100ps, the performance of electronics and PMTs must be continuously monitored by a high resolution laser calibration system. Here we report about the design, characterization, construction and installation of this light distribution system consisting of a picosecond laser source, a printed light circuit (PLC), long single mode fibers coupled to bundles of multimode fibers terminated with graded index microlenses, to provide illumination of all the PMT pixels with time jitter less than 50ps.

Test of the photon detection system for the LHCb RICH Upgrade in a charged particle beam

The LHCb detector will be upgraded to make more efficient use of the available luminosity at the LHC in Run III and extend its potential for discovery. The Ring Imaging Cherenkov detectors are key components of the LHCb detector for particle identification. In this paper we describe the setup and the results of tests in a charged particle beam, carried out to assess prototypes of the upgraded opto-electronic chain from the Multi-Anode PMT photosensor to the readout and data acquisition system.

Remote leakage current detector for identification of insulators discharges

Performances of high voltage insulators can be evaluated by analyses of leakage current (LC) patterns. When insulators are polluted, the development of the LCs may lead to discharges causing insulator flashovers. This paper proposes a simple method of identifying the state of discharge activities through remotely sensed LCs. A remote detector, which is capable of detecting LC by capturing resultant electromagnetic field, was first developed. Preliminary tests were conducted at the laboratory considering typical near-by interference effects on polluted insulators such as effects due to corona and line current in order to test the robustness of the proposed system under the said interference effects. The tests were extended by obtaining different LC patterns by conducting salt-fog spray tests on five different types of clean insulators (made of porcelain, glass and silicone rubber), at two salinity levels (10 g/L and 40 g/L) and six different voltage levels (50%–300% of rated voltage). LCs were also measured on five different field polluted insulators through clean fog tests. In order to verify the proposed method, LCs were measured directly for all the test cases. The directly measured LCs were classified in to three classes: sinusoidal, non-sinusoidal and discharge. The remotely sensed LCs were also classified to these three classes using a kurtosis analysis. The statistical measure of kurtosis was observed as a viable and robust parameter to distinguish these three classes based on the remote measurement. The sinusoidal class had kurtosis values less than 5; discharge group had kurtosis greater than 12; the non-sinusoidal class had kurtosis values between these two levels. Hence, this paper suggests the possibility of using kurtosis values of remotely sensed LCs to identify the state of discharge activity prior to the insulator flashover remotely while proving to be robust under typical interference effects.

SHiP: a new facility with a dedicated detector to search for new neutral particles and studying tau neutrino properties

SHiP (Search for Hidden Particles) is a new general purpose fixed target facility, whose Technical Proposal has been recently reviewed by the CERN SPS Committee and by the CERN Research Board. The two boards recommended that the experiment proceeds further to a Comprehensive Design phase in the context of the new CERNWorking group Physics Beyond Colliders, aiming at presenting a CERN strategy for the European Strategy meeting of 2019. In the initial phase of SHiP, the 400 GeV proton beam extracted from the SPS will be dumped on a heavy target with the aim of integrating 2×1020 pot in 5 years. A dedicated detector, based on a long vacuum tank followed by a spectrometer and particle identification detectors, will allow probing a variety of models with light long-lived exotic particles and masses below O (10) GeV/c2 . The main focus will be the physics of the so-called Hidden Portals, i.e. search for Dark Photons, Light scalars and pseudo-scalars, and Heavy Neutrinos. The sensitivity to Heavy Neutrinos will allow for the first time to probe, in the mass range between the kaon and the charm meson mass, a coupling range for which Baryogenesis and active neutrino masses could also be explained. Another dedicated detector will allow the study of neutrino cross-sections and angular distributions.

Silicon Carbide for Realization of “Telescope” Ion Detectors

SiC detectors for charged particle identification can be assembled as a “telescope” device. It represents a powerful detector showing some advantages with respect to the traditional silicon ones. Their high gap energy, high density, high sensitivity, and high radiation resistance confer indisputable advantages with respect to silicon. A special geometry for this telescope is proposed and discussed in order to detect ions from low kiloelectron-volts energy up to energies of 100 MeV using different fluence. An active depth of $100~\mu \text{m}$ is employed for the ion stopper detector and an active superficial layer of 4- $\mu \text{m}$ depth for the energy loss detector. Applications to low fluence use radioactive sources, while short plasma pulses generated by high intensity lasers are used at high fluence.

Organic and inorganic decomposition products from the thermal desorption of atmospheric particles

Abstract. Atmospheric aerosol composition is often analyzed using thermal desorption techniques to evaporate samples and deliver organic or inorganic molecules to various designs of detectors for identification and quantification. The organic aerosol (OA) fraction is composed of thousands of individual compounds, some with nitrogen- and sulfur-containing functionality and, often contains oligomeric material, much of which may be susceptible to decomposition upon heating. Here we analyze thermal decomposition products as measured by a thermal desorption aerosol gas chromatograph (TAG) capable of separating thermal decomposition products from thermally stable molecules. The TAG impacts particles onto a collection and thermal desorption (CTD) cell, and upon completion of sample collection, heats and transfers the sample in a helium flow up to 310 °C. Desorbed molecules are refocused at the head of a gas chromatography column that is held at 45 °C and any volatile decomposition products pass directly through the column and into an electron impact quadrupole mass spectrometer. Analysis of the sample introduction (thermal decomposition) period reveals contributions of NO+ (m/z 30), NO2+ (m/z 46), SO+ (m/z 48), and SO2+ (m/z 64), derived from either inorganic or organic particle-phase nitrate and sulfate. CO2+ (m/z 44) makes up a major component of the decomposition signal, along with smaller contributions from other organic components that vary with the type of aerosol contributing to the signal (e.g., m/z 53, 82 observed here for isoprene-derived secondary OA). All of these ions are important for ambient aerosol analyzed with the aerosol mass spectrometer (AMS), suggesting similarity of the thermal desorption processes in both instruments. Ambient observations of these decomposition products compared to organic, nitrate, and sulfate mass concentrations measured by an AMS reveal good correlation, with improved correlations for OA when compared to the AMS oxygenated OA (OOA) component. TAG signal found in the traditional compound elution time period reveals higher correlations with AMS hydrocarbon-like OA (HOA) combined with the fraction of OOA that is less oxygenated. Potential to quantify nitrate and sulfate aerosol mass concentrations using the TAG system is explored through analysis of ammonium sulfate and ammonium nitrate standards. While chemical standards display a linear response in the TAG system, redesorptions of the CTD cell following ambient sample analysis show some signal carryover on sulfate and organics, and new desorption methods should be developed to improve throughput. Future standards should be composed of complex organic/inorganic mixtures, similar to what is found in the atmosphere, and perhaps will more accurately account for any aerosol mixture effects on compositional quantification.

Gas gain stabilisation in the ATLAS TRT detector

The ATLAS (one of two general purpose detectors at the LHC) Transition Radiation Tracker (TRT) is the outermost of the three tracking subsystems of the ATLAS Inner Detector. It is a large straw-based detector and contains about 350,000 electronics channels. The performance of the TRT as tracking and particularly particle identification detector strongly depends on stability of the operation parameters with most important parameter being the gas gain which must be kept constant across the detector volume. The gas gain in the straws can vary significantly with atmospheric pressure, temperature, and gas mixture composition changes. This paper presents a concept of the gas gain stabilisation in the TRT and describes in detail the Gas Gain Stabilisation System (GGSS) integrated into the Detector Control System (DCS). Operation stability of the GGSS during Run-1 is demonstrated.

A time-based front-end ASIC for the silicon micro strip sensors of the P̄ANDA Micro Vertex Detector

The P̄ANDA (Antiproton Annihilation at Darmstadt) experiment foresees many detectors for tracking, particle identification and calorimetry. Among them, the innermost is the MVD (Micro Vertex Detector) responsible for a precise tracking and the reconstruction of secondary vertices. This detector will be built from both hybrid pixel (two inner barrels and six forward disks) and double-sided micro strip (two outer barrels and outer rim of the last two disks) silicon sensors. A time-based approach has been chosen for the readout ASIC of the strip sensors. The PASTA (P̄ANDA Strip ASIC) chip aims at high resolution time-stamping and charge information through the Time over Threshold (ToT) technique. It benefits from a Time to Digital Converter (TDC) allowing a time bin width down to 50 ps. The analog front-end was designed to serve both n-type and p-type strips and the performed simulations show remarkable performances in terms of linearity and electronic noise. The TDC consists of an analog interpolator, a digital local controller, and a digital global controller as the common back-end for all of the 64 channels.

Experimental Facility at A2 Collaboration (MAINZ) for Photoproduction reaction

<p>Since 20 years, a very successful experimental program with real photons has been achieved at the Mainz Microtron (MAMI) facility. The A2 Collaboration at MAINZ is a unique place for the experimental facility of photoproduction reaction. The combination of highly sensitive photo spectrometers Crystal Ball and TAPS as forward wall detector along with particle identification detector and Multiwire proportional chambers as inner wall detectors provide the high precision of the measurement. MAMI-C, which consists of there Race Track Microtrons (RTMs) with the Harmonic Double -Sided Microtron (HDSM) is an intense, stable and continuous-wave accelerator to accelerate electron to 1.5 GeV. This electron beam is responsible to produce real photons via bremsstrahlung process at Glasgow Photon Tagger. A major part of the ongoing and future programme at MAMI will exploit polarised nucleon targets.</p><p>Journal of Nepal Physical Society Vol.3(1) 2015: 73-81</p>

Fusion of Different Height Pyroelectric Infrared Sensors for Person Identification

Due to the instability and poor identification ability of a single pyroelectric infrared (PIR) detector for human target identification, this paper presents a PIR detection identification system that can collect thermal infrared features from different parts of human targets through multiple PIR sensors for the human identification. First, fast Fourier transform, short-time Fourier transform, and wavelet packet transform algorithms are adopted to extract thermal infrared features of human targets. Then, the canonical correlation analysis algorithm is used to fuse different algorithm features in the feature layer. Finally, using the support vector machine to classify the human targets. In the decision-making layer, the Dempster/Shafer evidence theory is adopted to optimize the recognition results from different PIR sensors that locate at different height positions. Extensive experimental results demonstrate that the fusion of feature layer data could improve the average recognition rate of the human target with closer distance from the single sensor. In addition, the fusion of decision-making layer could improve the recognition ability of the identification system as well. When the detection distance is 6 m, the correct recognition rate of fusion system is still reached 88.75%. Compared with the system using a single sensor, the recognition rate is increased by an average of 22.67%.