ARGO-YBJ detector simulation using GEANT4

'G4argo', a GEANT4-based simulation package for the ARGO-YBJ detector, is described in this paper. G4argo incorporates in the simulation the true RPC time resolution and another 0.5 ns time uncertainty which is introduced from the offline calibration of TDC. In addition, the correct RPC geometry and the true materials for the ARGO-YBJ experimental hall are implemented. As a result, G4argo simulation shows a very good agreement with real data.     

Energy spectrum of cosmic protons and helium nuclei by ahybrid measurement at 4300 m a.s.l.

The energy spectrum of cosmic Hydrogen and Helium nuclei has been measured below the so-called "knee" by using a hybrid experiment with a wide field-of-view Cherenkov telescope and the Resistive Plate Chamber (RPC) array of the ARGO-YBJ experiment at 4300 m above sea level. The Hydrogen and Helium nuclei have been well separated from other cosmic ray components by using a multi-parameter technique. A highly uniform energy resolution of about 25% is achieved throughout the whole energy range (100-700 TeV). The observed energy spectrum is compatible with a single power law with index γ=-2.63±0.06.     

A simulation study of the e~+/e~- sensitivity of a low resistive phosphate glass electrode in a RPC using GEANT MC

The resistivity of conventional glass is quite high and is unacceptable in a high rate environment. Low resistive glass-electrodes could be a solution for this problem. The present study reports the e+/e-simulation results of an RPC detector made from low resistive phosphate glass electrodes. The detailed geometrical configuration of the content materials which are the essential components of the glass of the RPC detector have been created with the GEANT4 simulation code. Two different types of particle sources, i.e. for e+/e-, have been located on the detectors surface to evaluate the performance of the phosphate glass RPC. Both of the particles have been simulated as a function of their respective energies in the range of 0.1 MeV – 1.0 GeV. The present simulation work has shown that the resistive electrode plays an important role for the particle production in the RPC configuration.     

Study of neutron response for two hybrid RPC setups using the GEANT4 MC simulation approach

The present article describes a detailed neutron simulation study in the energy range 10~(-10) MeV to 1.0 GeV for two different RPC configurations.The simulation studies were taken by using the GEANT4 MC code.Aluminum was utilized on the GND and readout strips for the (a) Bakelite-based and (b) glass-based RPCs.For the former type of RPC setup the neutron sensitivity for the isotropic source was S_n=2.702×10~(-2) at E_n=1.0 GeV, while for the latter type of RPC, the neutron sensitivity for the same source was evaluated as S_n=4.049×10~(-2) at E_n=1.0 geV.These results were further compared with the previous RPC configuration in which copper was used for ground and pickup pads.Additionally A1 was employed at (GND+strips) of the phosphate glass RPC setup and compared with the copper-based phosphate glass RPC.Good agreement with sensitivity values was obtained with the current and previous simulation results.     

Radon contribution to single particle counts of the ARGO-YBJ detector

The ARGO-YBJ experiment is an air shower detector for gamma ray astronomy and cosmic ray studies with an energy threshold of ∼500 GeV. Working in “single particle mode”, i.e. counting the single particles hitting the detector at fixed time intervals, ARGO-YBJ can monitor cosmic ray and gamma ray transients at energies of a few GeV.The single particle counting rate is modulated by the atmospheric pressure and temperature, and is affected by the local radioactivity from soil and air. Among the radioactive elements, radon gas is of particular importance since its concentration in air can vary significantly, according to environmental conditions. In this paper we evaluate the contribution of the radon daughter gamma ray emitters to the single particle counting rate measured by ARGO-YBJ. According to our analysis, the radon gas contribution is roughly 1–2%, producing a counting rate modulation of the same order of magnitude of the atmospheric effects.     

Sensitivity study of(10,100) GeV gamma-ray bursts with double shower front events from ARGO-YBJ

ARGO-YBJ, located at the Yangbajing Cosmic Ray Observatory(4300 m a.s.l., Tibet, China), is a full coverage air shower array, with an energy threshold of ~300 Ge V for gamma-ray astronomy. Most of the recorded events are single front showers, satisfying the trigger requirement of at least 20 particles detected in a given time window. However, in ~11.5% of the events, two randomly arriving showers may be recorded in the same time window,and the second one, generally smaller, does not need to satisfy the trigger condition. These events are called double shower front events. By using these small showers, well under the trigger threshold, the detector primary energy threshold can be lowered to a few tens of Ge V. In this paper, the angular resolution that can be achieved with these events is evaluated by a full Monte Carlo simulation. The ARGO-YBJ sensitivity in detecting gamma-ray bursts(GRBs) by using double shower front events is also studied for various cutoff energies, time durations, and zenith angles of GRBs in ARGO's field of view.     

A simulation study of the e~+/e~- sensitivity of a low resistive phosphate glass electrode in a RPC using GEANT MC

The resistivity of conventional glass is quite high and is unacceptable in a high rate environment. Low resistive glass-electrodes could be a solution for this problem. The present study reports the e+/e-simulation results of an RPC detector made from low resistive phosphate glass electrodes. The detailed geometrical configuration of the content materials which are the essential components of the glass of the RPC detector have been created with the GEANT4 simulation code. Two different types of particle sou...     

GEANT4 simulation of gamma ray in a double-gap resistive plate chamber

For more than 20 years nuclear physicists have used the GEANT code to simulate particle-matter interaction. In most recent version, GEANT4 is a toolkit for simulating the passage of particles though matter, which contains a complete range of functionality including tracking, geometry, physics models, and hits. In this article, an attempt to use GEANT4 to model a double-gap resistive plate chamber （RPC） with its improved efficiency is presented. The efficiencies of the double-gap RPC have been evaluated as a function of gamma energy range 0.005-1000MeV. A comparison to available previous simulation package GEANT3 data is also performed.     

近地雷暴电场与羊八井地面宇宙线关联的模拟研究

雷暴期间地面宇宙线强度变化的研究对理解大气电场加速宇宙线次级带电粒子的物理机理具有重要意义. 分析西藏羊八井ARGO实验中2012年大气电场的数据后发现, 近地雷暴电场的强度可达1000 V/cm甚至更高. 用Monte Carlo方法模拟研究了近地雷暴电场与羊八井地面宇宙线强度的关联. 当雷暴电场强度(取1500 V/cm)大于逃逸电场时, 宇宙线次级粒子中正、负电子的数目呈指数增长, 在大气深度约520 g/cm²处达到极大值, 与Gurevich等提出的相对论电子逃逸雪崩机理和Dwyer理论相符. 当雷暴电场强度小于逃逸电场时, 在所有负电场范围和大于600 V/cm的正电场范围, 总电子数目随电场强度的增大而增加; 当正电场小于400 V/cm时, 总电子数目均出现一定幅度的下降; 在电场为400–600 V/cm范围内, 总电子数目的变化与原初粒子的能量有关, 原初能量小于80 GeV时, 其次级粒子中总电子数目增加, 原初能量在80–120 GeV 范围内时, 总电子数目变化不明显, 原初能量大于120 GeV时, 总电子数目出现下降, 下降幅度约4%. 模拟结果可对羊八井ARGO实验的观测结果给予合理的解释.     

Performances and long-term stability of the LHAASO-KM2A prototype array

A prototype array for the LHAASO-KM2A, which consists of 42 detector units and fully overlaps the ARGO-YBJ experiment, was set up at the Yangbajing cosmic ray observatory and has been in stable operation since Octoter 2010. The resulting performances of the KM2A electromagnetic particle detector prototypes fully meet the design requirements. Through hybrid observation of cosmic ray showers with the ARGO-YBJ experiment, the performances and long-term stability of the prototype array are tested and the results are consistent with expectation. The cosmic ray moon shadow observed by the prototype array is also presented.     

Estimation of the proton energy spectrum in knee region by analog read-out of ARGO-YBJ experiment

Based on the six months data set of ARGO-YBJ experiment with analog read-out and its Monte Carlo simulation, we study the difference between different primaries induced showers by using the space-time information of the charged particles in Extensive Air Showers. With five parameters which can efficiently pick out primary proton induced showers as inputs of an artificial neural network, the proton spectrum from 100 TeV to 10 PeV can be obtained.     

Background neutron in the endcap and barrel regions of resistive plate chamber for compact muon solenoid/large hadron collider using GEANT4

In this study the performance of double gap RPC has been tested by GEANT4 Monte Carlo simulation code. The detector response calculations taken as a function of the neutron energy in the range of 0.01 eV-1 GeV have been simulated through RPC set-up. In order to evaluate the response of detector in the LHC background environment, the neutron spectrum expected in the CMS muon endcap and barrel region were taken into account. A hit rate of about 165.5 Hz cm⁻², 34 Hz cm⁻², 33.6 Hz cm⁻², and 27.0 Hz cm⁻² due to an isotropic neutron source is calculated using GEANT4 standard electromagnetic package for a 20 × 20 cm² RPC in the ME1, ME2, ME3 and ME4, respectively. While for the same neutron source and using GEANT4 package a hit rate of about 0.42 Hz cm⁻², 0.7182 Hz cm⁻² was measured for the MB1 and MB4 stations respectively. Similar characteristics of hit rates have been observed for GEANT4 low electromagnetic package.      

Highlights of the ARGO-YBJ Experiment at 4,300 m a.s.l.

The ARGO-YBJ experiment in Tibet, China has been operated to survey the northern sky for gamma ray sources, transient or steady, for nearly 6 years. Many astrophysics observational results will be highlighted in this paper, such as the sky survey results, extended source observation, diffuse gamma rays from the galactic plane, and emission mechanism of AGNs and their flares. As the unique detector for EAS with a continuously sensitive area of 5,600 m ², the ARGO-YBJ array catches almost all particles in the central part of showers. The high-quality data set for showers above few TeV has been used for cosmic ray measurements such as the energy spectrum and composition. All those results are summarized here. As one of the next generation ground-based high-altitude air shower detector, LHAASO is briefly introduced as the successor of ARGO-YBJ in the end of the paper.     

Estimation of the proton energy spectrum in knee region by analog read-out of ARGO-YBJ experiment

Based on the six months data set of ARGO-YBJ experiment with analog read-out and its Monte Carlo simulation,we study the difference between different primaries induced showers by using the space-time information of the charged particles in Extensive Air Showers.With five parameters which can efficiently pick out primary proton induced showers as inputs of an artificial neural network,the proton spectrum from 100 TeV to 10 PeV can be obtained.     

Simulation study using GEANT4 Monte Carlo code for a Gd-coated resistive plate chamber as a thermal neutron detector

The Resistive Plate Chamber (RPC) has been developed in many application areas ever since its introduction, from high energy physics experiments to positron emission tomography. Such detectors can be coated with a Gd layer that enables them to detect thermal neutrons. Consequently these RPCs can be utilized for industrial and medical purposes. Here, we present the configuration of a resistive plate chamber which is utilized to detect thermal neutrons by employing GEANT4 Monte Carlo code. The response of the RPC was evaluated as a function of neutron energy in the GEANT4 Monte Carlo code. The simulation results are taken for incident neutron energy in the energy range from 25 meV to 100 meV. The detection efficiency was found to be between 10% and 20%, depending on the detector configuration, for incident thermal neutrons of 25 meV energy.     

Study of readout and cross-talks for multi-strip RPC with PSpice simulation

An electrical model for multi-strip resistive plate chamber (RPC) is presented,and a comparison between simulation results and test data is carried on.Based on the model,the influences of the RPC's design parameters on the readout are studied with PSpice simulation.Cross-talk (CT) phenomenon is observed and the relative amplitudes of the CT are studied for different design parameters.     

全尺寸CMS RE1/2阻抗板探测器样器束流测试结果

介绍了CMS RE1/2 全尺寸阻抗板探测器的束流测试结果.探测器气体室的阻抗板表面采用不需要淋油的特殊光洁处理,外支撑框架采用铝质蜂窝板,以保证足够的强度以及整个RPC所占空间尽量小.在GIF的束流测试结果表明该样品在高辐射本底下能够达到满探测效率.时间分辨率以及噪声水平都符合CMS实验的要求.     

Beam Test Results of the First Full-Scale Prototype of CMS RE1/2 Resistive Plate Chamber

We reported the muon beam test results of the first full–scale prototype of CMS RE1/2 Resistive Plate Chamber (RPC).The bakelite surface is treated using a special technology without oil to make it smooth enough.The full scale RE1/2 RPC with honeycomb supporting frame is strong and thin enough to be fitted to the limited space of CMS design for the inner forward RPC.The muon beam test was performed at CERN Gamma Irradiation Facility (GIF).The detection efficiency of this full scale RPC prototype is>95% even at very high irradiation background.the time resolution (less than 1.2 ns) and spatial resolution are satisfactory for the muon trigger device in future CMS experiments.The noise rate is also calculated and discussed.     

Effect of the integrated time of the induced current signal on the position resolution of the RPC detector

A prototype RPC with position resolution less than 1 mm has been produced and studied. Based on this RPC detector, the effect of the width of the integrated FADC time window on the position resolution of a RPC has been studied experimentally and theoretically. The results of theoretical calculation and experimental measurement have shown good agreement.     

Effect of the integrated time of the induced current signal on the position resolution of the RPC detector

A prototype RPC with position resolution less than 1 mm has been produced and studied. Based on this RPC detector, the effect of the width of the integrated FADC time window on the position resolution of a RPC has been studied experimentally and theoretically. The results of theoretical calculation and experimental measurement have shown good agreement.