Charge Identification Research Articles

Improvement of charge resolution for trans-iron nuclei (<i>Z</i> ≥ 30) in CR-39 plastic nuclear track detectors using trajectory tracing technique

Charge identification of trans-iron nuclei (nuclear charge: Z = 30) using CR-39 plastic nuclear track detector (PNTD) is essential as a part of an effort to our future mea- surements of the projectile charge changing cross sections for galactic cosmic ray nuclei, but extremely hard. There- fore, an improvement method of the charge resolution (Z ) for 350 MeV/n Ge in CR-39 PNTD using the trajectory trac- ing technique with averaging the signals of nuclear tracks for each ion was studied. Eight sheets of CR-39 PNTDs were aligned and exposed to Ge beam behind a graphite target to produce projectile fragments. Average of the nuclear track data was taken over 16 detector surfaces for each ion, then the Z of Ge was successfully improved from 0.31 charge unit on single surface to 0.15 charge unit in rms, which is good enough for making the precise cross section measure- ments and no other experiments using CR-39 PNTDs or the other passive detectors have achieved such a good Z for the trans-iron nuclei with Z/ < 50 ( : relativistic velocity). This method will be very important for our future cross sec- tion measurements toward the study of galactic cosmic ray origin.

Simulation and reconstruction of the PANDA Barrel DIRC detector**Work supported by EU FP6 grant, contract number 515873, DIRAC secondary-beams and EU FP7 grant, contract number 227431, HadronPhysics2, HGS-Hire and HIC for FAIR.

The PANDA experiment at the future Facility for Antiproton and Ion Research (FAIR) at GSI, Darmstadt, aims at studying the strong interacting matter by precision spectroscopy. A detector system with excellent particle identification over a large range of solid angle and momentum is therefore mandatory. Charged hadron identification in the barrel region will be performed by a compact ring imaging Cherenkov detector based on the DIRC principle (Detection of Internally Reflected Cherenkov light), designed to separate pions from kaons with at least 3 standard deviations in the momentum range from 0.5 GeV/c to 3.5 GeV/c. We present details of the simulation of the PANDA Barrel DIRC and a study of the detector performance using a fast reconstruction algorithm to determine the single photon Cherenkov angle resolution and photon yield for several design options.

Beam test performance of a scintillator-based detector for the charge identification of relativistic ions

Abstract We report on the measurements performed with relativistic ions from Be to Fe, at the Fragment Separator (FRS) of the GSI Helmholtzzentrum fur Schwerionenforschung in Darmstadt, to test the performance of charge-sensitive detectors that were designed to separate – via multiple d E /d x measurements – fully stripped nuclei of cosmic origin in the experiment CALET. The latter is a space mission by the Japanese Space Agency (JAXA) scheduled to be launched to the International Space Station (ISS) in 2013. The CALET instrument is managed by an international collaboration and it is scheduled to take data for 5 years on the Exposure Facility (JEM-EF) of the Japanese module KIBO on the ISS. The aim of the test was to accurately measure the response of the scintillator to different nuclear species and parametrize the saturation of the scintillation light in order to assess the impact of this effect on the charge resolution of the instrument.

Top quark anomalous couplings at the International Linear Collider

We present a study of the experimental determination of the forward-backward asymmetry in the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}t\overline{t}$ and in the subsequent $t\ensuremath{\rightarrow}Wb$ decay, studied in the context of the International Linear Collider. This process probes the elementary couplings of the top quark to the photon, and the $Z$ and the $W$ bosons at a level of precision that is difficult to achieve at hadron colliders. Measurement of the forward-backward asymmetry requires excellent $b$ quark identification and determination of the quark charge. The study reported here is performed in the most challenging all-hadronic channel ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}b\overline{b}q\overline{q}q\overline{q}$. It includes realistic details of the experimental environment, a full Monte Carlo simulation of the detector, based on the Silicon Detector concept, and realistic event reconstruction. The forward-backward asymmetries are determined to a precision of approximately 1% for each of the two choices of beam polarization. We analyze the implications for the determination of the $t\overline{t}Z$ and $Wt\overline{b}$ couplings.

Charged particle identification with PHOS and central tracking of ALICE

The ALICE Photon Spectrometer (PHOS) has been designed to measure the photon spectrum produced in pp and AA collisions at LHC over a broad transverse momentum range from 0.5–100 GeV/c. We present a study on the matching of charged tracks, detected by the ALICE central tracking detectors, with clusters of hit PHOS elements. Matching efficiency and contamination due to false matches have been deduced for charged pions, muons and electrons. The study indicates also that material from other detectors in front of PHOS disturbs the photon detection.

Nuclei charge identification for the galactic cosmic ray transuranic elements by the chemically etching tracks in the pallasite olivine crystals

Nuclei charge identification for the galactic cosmic ray transuranic elements by the chemically etching tracks in the pallasite olivine crystals

Charged pion identification at high p. T in ALICE using the TPC dE/dx

The ALICE TPC provides excellent charged particle tracking to study pp and Pb-Pb collisions at LHC. The TPC allows also particle identification (PID) via the measurement of the specific ionisation dE/dx. At high p(T) (p(T) > 3 GeV/c) this is accomplished in the region of the relativistic rise of the energy loss, and provides a measurement of the yields of charged pions, kaons; and protons. Here, we present the performance of such an analysis in pp collisions at 7 TeV for charged pions up to 10 GeV/c. On the relativistic rise, statistical PID can be used to evaluate the yields for pions, protons and kaons for p(T) > 3 GeV/c. Here, we show first performance results from such an analysis for charged pions up to 10 GeV/c.

Particle identification for the [formula omitted] detector

Cooled antiproton beams of unprecedented intensities in the momentum range of 1.5–15 GeV/ c will be used for the P ¯ ANDA experiment at FAIR to perform high precision experiments in the charmed quark sector. The proposed P ¯ ANDA detector is a 4 π internal target spectrometer at the HESR allowing the detection and identification of neutral and charged particles generated within the total energy range of the antiproton annihilation products. The detector is divided in a forward spectrometer and a target spectrometer. The charged particle identification in the latter is performed by ring imaging Cherenkov counters employing the DIRC principle.

The ALICE-HMPID Detector Control System: Its evolution towards an expert and adaptive system

The High Momentum Particle IDentification (HMPID) detector is a proximity focusing Ring Imaging Cherenkov (RICH) for charged hadron identification. The HMPID is based on liquid C 6F 14 as the radiator medium and on a 10 m 2 CsI coated, pad segmented photocathode of MWPCs for UV Cherenkov photon detection. To ensure full remote control, the HMPID is equipped with a detector control system (DCS) responding to industrial standards for robustness and reliability. It has been implemented using PVSS as Slow Control And Data Acquisition (SCADA) environment, Programmable Logic Controller as control devices and Finite State Machines for modular and automatic command execution. In the perspective of reducing human presence at the experiment site, this paper focuses on DCS evolution towards an expert and adaptive control system, providing, respectively, automatic error recovery and stable detector performance. HAL9000, the first prototype of the HMPID expert system, is then presented. Finally an analysis of the possible application of the adaptive features is provided.

Software development for the P¯ANDA barrel DIRC

The charged particle identification in the barrel region of the P ¯ ANDA detector in the future FAIR facility at GSI is planned with a very thin Cherenkov detector using the DIRC principle. Due to a very compact design of the barrel DIRC with focusing optics, the reconstruction of the Cherenkov angle is quite challenging. In this contribution, the possible reconstruction algorithm of the barrel DIRC will be discussed, with emphasis on the possibility to include the DIRC in the trigger decision and the correction of the chromatic dispersion with fast timing information.

The barrel DIRC detector for the P¯ ANDA experiment at FAIR

The P ¯ ANDA experiment at FAIR will perform high precision experiments in the charmed quark sector using cooled antiproton beams of unprecedented intensities of L=2×10 32 cm −2 s −1 in the momentum range of 1–15 GeV/ c. The charged particle identification in the barrel region needs a thin detector operating in a strong magnetic field. A ring imaging Cherenkov detector using the DIRC principle is an excellent match to those requirements. This article describes aspects of the design and R&D for the P ¯ ANDA barrel DIRC detector. The availability of highly pixelated fast photon detectors allows several key improvements compared to the successful BaBar-DIRC detector, some of which were tested in a proton beam at GSI. The optical properties of the radiator bars, made from synthetic fused silica, are critical to the success of the DIRC. Measurements of the attenuation length and reflection coefficient allow the determination of the surface roughness of prototype radiator bars.

The time-of-propagation counter for BelleII

The Belle II detector operating at the future upgrade to the KEKB accelerator will perform high-statistics precision investigations into the flavor sector of the Standard Model. As charged hadron identification is a vital element of the experiment's success, the time-of-propagation (TOP) counter has been chosen as the primary particle identification device in the barrel region of Belle II. The TOP counter is a compact variant of the detection of internally reflected Cherenkov light (DIRC) technique and relies heavily on exquisite single photon timing resolution with micro-channel plate photomultiplier tubes. We discuss the general principles of TOP operation and optimization of the Belle II TOP configuration, which is expected to provide 4 sigma or better separation of kaons and pions up to momenta of approximately 4 GeV/ c.

A focussing disc DIRC for PANDA

The PANDA experiment at the FAIR upgrade to GSI, Darmstadt, aims to study modern hadronic physics with unprecedented precision. Excellent particle identification of both charged and neutral particles is necessary to achieve the physics aims of PANDA. Two DIRC detectors are foreseen for charged particle identification, one in a barrel configuration for the central region, and the second in a disc configuration for the forward endcap. The design of the forward disc DIRC centres around the novel application of passive chromatic dispersion correction elements, allied with focussing optics, to achieve excellent resolution of Chernekov angle. A system of comprehensive prototype development will show the feasibility of the system. Key to the success of the prototype is fully understanding the production, transport and detection of the Cherenkov photons within the detector. Photon yield and its dependence on the polar angle of the detector have been measured. Observed photon yield is also the basis for subsequent studies into the benefit of chromatic dispersion correction elements, focussing and overall detector performance.

The LHCb RICH silica aerogel performance with LHC data

In the LHCb experiment at the Large Hadron Collider, powerful charged particle identification is performed by Ring Imaging CHerenkov (RICH) technology. In order to cover the full geometric acceptance and the wide momentum range (1–100 GeV/ c), two detectors with three Cherenkov radiators have been designed and installed. In the medium (10–40 GeV/ c) and high (30–100 GeV/ c) momentum ranges, gas radiators are used (C 4F 10 and CF 4, respectively). In the low momentum range (1–10 GeV/ c), pion, kaon and proton separation is performed with solid silica aerogel radiator. A set of 16 tiles, with large transverse dimensions of up to 200 × 200 mm 2 and nominal refractive index 1.03 have been produced and integrated in the detector. These tiles have excellent optical properties and homogeneity of the refractive index at the percent level within the tile. The first data collected at the LHC are used to investigate the behaviour of the RICH; preliminary results of the performance of silica aerogel are presented and discussed.

The AMS-02 RICH detector: Performance during ground-based data taking at CERN

The Alpha Magnetic Spectrometer (AMS), whose final version AMS-02 is to be installed on the International Space Station (ISS) in 2011, is a detector designed to measure charged cosmic ray spectra with energies up to the TeV region and with high energy photon detection capability up to a few hundred GeV, using state-of-the art particle identification techniques. Among several detector subsystems, AMS includes a proximity focusing RICH detector enabling precise measurements of particle electric charge (charge identification up to the iron region) and velocity ( Δ β / β ∼ 10 − 3 for Z=1, Δ β / β ∼ 10 − 4 for Z=10–20). The optimization of the RICH reconstruction efficiency imposed a dual radiator configuration with 16 NaF tiles ( n=1.33) in the centre and 92 aerogel tiles ( n=1.050) in the outer region, a pixelized detection matrix with 680 Hamamatsu R7600-M16 photomultipliers (each with 4×4 pixels) and a highly reflective conical mirror to increase photon collection. After its assembly at CIEMAT in Madrid, the RICH was taken to CERN in January 2008 and integrated into the full AMS-02 detector. AMS-02 underwent a pre-assembly in 2008 without magnet followed by a second detector assembly with a superconducting magnet in 2009 and the final assembly with a permanent magnet in mid-2010. Cosmic events were acquired in the context of the 2008 pre-assembly and in 2009, and two beam tests from CERN SPS took place in 2010. Results obtained with data from ground-based tests on the RICH performance are presented. A comparison with the aerogel light yield obtained on previous beam tests with a prototype detector is also discussed.

TORCH: Time of flight identification with Cherenkov radiation

TORCH is a time-of-flight detector concept using Cherenkov light to provide charged particle identification up to 10 GeV/ c. The concept and design are described and performance in simulation is quantified.

Development of DIRC counters for the PANDA experiment at FAIR

The PANDA experiment at the planned FAIR facility at GSI, Darmstadt, aims at measuring hadronic final states with unprecedented precision and luminosity. Superior particle identification of charged and neutral particles is mandatory to fulfil PANDA's physics aims. DIRC (Detection of Internally Reflected Cherenkov light) counters are foreseen for charged particle identification. A barrel DIRC will cover the central region while a disc DIRC will provide particle identification in the forward region. Three DIRC concepts differing in the radiator geometry and method for dispersion correction are studied. The barrel DIRC uses a novel imaging system and aims at exploiting a 3D reconstruction to mitigate dispersion effects. Two concepts are investigated for the forward disc DIRC. One concept employs passive dispersion correction and focussing light guides for image reconstruction. Alternatively, time-of-propagation measurements and a wave-length dependent photon detection system are investigated. The three detector designs share common developments such as investigating radiator properties and photon detection systems, and use the same test beam facilities.

Advances in charged particle identification techniques

The steady progress made over the past years in the design of innovative particle identification detectors has allowed to achieve relevant physics results in various experiments. The current investigation of new challenging approaches will seed future applications to the planned experiments at the SuperB factories and at the forthcoming FAIR facility, which demand an unrivalled particle identification performance. This paper will provide the current state of the art in the major charged particle identification techniques and will discuss the most significant advances and the most promising future directions.

Impact of detector parameters on light charged particle and intermediate mass fragments identification through pulse-shape analysis

The aim of this work is the study of the impact of the real preamplifier-detector configuration (i.e. finite bandwidth, input noise, leakage current, detector capacitance) on the measurement techniques used for fragment identification in charge and mass in multi-detector arrays for intermediate energy nuclear physics experiments. We refer to rise-time vs. energy diagram – that allows charge identification and ToF techniques – used for the identification of mass. In this work we derived a first model able to predict the detection system performance and useful to tailor both the detector and the front-end specifications to the specific experimental case. The requirements for the optimization result to be partly conflicting ToF technique requires fast timing signals, while pulse-shape analysis benefits from slower detector pulses.

Gas Mixture Dependence of the Performance for Multigap Resistive Plate Chambers in the Avalanche Mode

is larger than 90%, the best time resolution is 123 ps, and the fraction of the non-Gaussian tail in the time spectrum is about 15%. The slewing corrections significantly improve the time resolution by about 40% at 6.4 kV, which is the operational high voltage. Although the addition of SF6 to the gas mixture is necessary for avalanche mode operation, a relatively small fraction is preferrable for a better time resolution. The present results demonstrate that the current multigap resistive plate chambers can be used for charged particle identification at high momentum in real collision experiments.