Discriminating cosmic muons and X-rays based on rise time using a GEM detector

Gas electron multiplier(GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade.In this work,a triple GEM device with an effective readout area of 10 cm x10 cm is developed,and a method of discriminating between cosmic muons and X-rays based on rise time is tested.The energy resolution of the GEM detector is tested by ~(55)Fe ray source to prove the GEM detector has a good performance.Analysis of the complete signal-cycles allows us to get the rise time and pulse heights.The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold.     

MACRO, a large-area detector at the Gran Sasso Laboratory

Summary MACRO is a large-area detector to be installed in hall B of the Gran Sasso Laboratory. Making use of scintillation counters, plastic streamer tubes, and track-etch detectors, it is designed to search for superheavy magnetic monopoles beyond the Parker bound, high-energy gamma and neutrino cosmic sourcs, and, more in general, exotic phenomena in the cosmic radiation. MACTO is an acronym for Monopole, Astrophysics and Cosmic Ray Observatory. The present collaboration: Bari(**)C. De Marzo, O. Erriquez, N. Giglietto andF. Posa. Bologna(**):M. Attolini, F. Baldetti, G. Giacomelli, F. Grianti, A. Margiotta andP. Serra. Caltech:B. Barish, C. Lane andG. Liu. CERN:P. Musset, G. Poulard andH. Sletten. Drexel:R. Steinberg. Laboratori Nazionali di Frascati dell'INFN:G. Battistoni, H. Bilokon, C. Bloise, P. Campana, V. Chiarella, A. Ciocio, A. Grillo, E. Iarocci, A. Marini, A. Rindi, F. Ronga, L. Satta, M. Spinetti, L. Trasatti andV. Valente. Indiana:S. Ahlen, B. Brabson, R. Heinz, S. Mufson, H. Ogren andP. Smith. Michigan:J. Musser, J. Stone, L. Sulak andG. Tarlé. Pisa(**):C. Angelini, A. Baldini, C. Bemporad, A. Cnops, V. Flaminio, G. Giannini, R. Pazzi andB. Saitta. Roma(**):G. Auriemma, M. De Vincenzi, E. Lamanna, G. Martellotti, S. Petrera, L. Petrillo, P. Pistilli, G. Rosa, A. Sciubba andM. Severi. Texas A&M:R. Webb. Torino:M. Arneodo, G. Borreani, P. Giubellino, F. Marchetto, A. Marzari, S. Palestini andL. Ramello.Virginia Tech:S. Torres andP. Trower. (**) Sezione INFN e Dipartimento di Fisica dell'Università.     

Search for UHE cosmic sources with a large-area underground muon detector

Summary The newly discovered gamma-ray emission from Cyg-X 3 with energies up to 2·10¹⁶eV gives the first evidence that particle acceleration in galactic gamma-ray sources can reach energies of the order of 10⁴ TeV. We discuss the detectability of this type of sources by an underground muon tracking detector with area of the order of ∼1000 m² and the physical information which could be obtained in this way. Paper presented at the 2° Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984.     

A novel CZT detector using strengthened electric field line anode

In this paper, we report on the design, simulation and testing of a novel CZT detector with an electrode named the Strengthened Electric Field Line Anode (SEFLA). The Strengthened Electric Field (SEF) technique and Single Polarity Charge Sensing (SPCS) technique are implemented. It could achieve the same performance as Coplanar Grid, Pixel Array CZT detectors but requires only a simple readout system. Geant4, Ansoft Maxwell and a self-developed Induced Current Calculator (ICC) package are used to develop an understanding of how the energy spectrum is formed, and the parameters of the detector are optimized. A prototype is fabricated. Experimental results demonstrate the effectiveness of this design. The test shows that the SEFLA detector achieves a FWHM of 6.0% @59.5 keV and 1.6% @662 keV, which matches well with the simulations.     

Study on the novel neutron-to-proton convertor for improving the detection efficiency of a triple GEM based fast neutron detector

A high-efficiency fast neutron detector prototype based on a triple Gas Electron Multiplier(GEM) detector, which, coupled with a novel multi-layered high-density polyethylene(HDPE) as a neutron-to-proton converter for improving the neutron detection efficiency, is introduced and tested with the Am-Be neutron source in the Institute of Modern Physics(IMP) at Lanzhou in the present work. First, the developed triple GEM detector is tested by measuring its effective gain and energy resolution with55 Fe X-ray source to ensure that it has a good performance.The effective gain and obtained energy resolution is 5.0×104and around 19.2%, respectively. Secondly, the novel multi-layered HDPE converter is coupled with the cathode of the triple GEM detector making it a high-efficiency fast neutron detector. Its effective neutron response is four times higher than that of the traditional single-layered conversion technique when the converter layer number is 38.     

Development of large-area quadrant silicon detector for charged particles

The quadrant silicon detector, a kind of passivated implanted planar silicon detector with quadrant structure on the junction side, gained its wide application in charged particle detection. In this paper, the manufacturing procedure, performance test and results of the quadrant silicon detector developed recently at the China Institute of Atomic Energy are presented. The detector is about 300 μm thick with a 48 mm×48 mm active area. The leakage current under the full depletion bias voltage of -16 V is about 2.5 nA, and the rise time is better than 160 ns. The energy resolution for a 5.157 MeV α-particle is around the level of 1%. Charge sharing effects between the neighboring quads, leading to complicated correlations between two quads, were observed when α particles illuminated on the junction side. It is explained as a result of distortion of the electric field of the inter-quad region. Such an event is only about 0.6% of all events and can be neglected in an actual application.     

An X-ray imaging device based on a GEM detector with delay-line readout

An X-ray imaging device based on a triple-GEM （Gas Electron Multiplier） detector, a fast delay-line circuit with 700 MHz cut-off frequency and two dimensional readout strips with 150 μm width on the top and 250 μm width on the bottom, is designed and tested. The localization information is derived from the propagation time of the induced signals on the readout strips. This device has a good spatial resolution of 150 μm and works stably at an intensity of 105 Hz/mm2 with 8 keV X-rays.     

Design and construction of a TPC prototype based on GEM detector readout

A time projection chamber (TPC) readout by gas electron multipliers (GEM) detector is a very promising candidate for the central tracking system of ILC (International Linear Collider). A prototype is designed and set up in our lab and introduced here. The tests during and after the assembly prove that the prototype TPC has been constructed successfully. It is ready for further study.     

基于GEM读出的TPC原型设计与建造

基于GEM探测器读出的TPC漂移室,具有非常多的优势,是ILC中央径迹探测器的首选方案之一。本文介绍了一个GEM－TPC原型机的设计。通过对该原型机进行的一系列测试,证明了该系统设计合理、搭建成功,已具备其基本功能,可以进行深入的测试研究。     

Design and optimization of resistive anode for a two-dimensional imaging GEM detector

A resistive anode for two-dimensional imaging detectors,which consists of a series of high resistivity pads surrounded by low resistivity strips,can provide good spatial resolution while reducing the number of electronics channels required.The optimization of this kind of anode has been studied by both numerical simulations and experimental tests.It is found that to obtain good detector performance,the resistance ratio of the pads to the strips should be larger than 5,the nonuniformity of the pad surface resistivity should be less than 20%,a smaller pad width leads to a smaller spatial resolution,and when the pad width is 6 mm,the spatial resolution(σ) can reach about 105μm.Based on the study results,a 2-D GEM detector prototype with optimized resistive anode is constructed and a good imaging performance is achieved.     

An X-ray imaging device based on a GEM detector with delay-line readout

An X-ray imaging device based on a triple-GEM (Gas Electron Multiplier) detector, a fast delay-line circuit with 700 MHz cut-off frequency and two dimensional readout strips with 150 μm width on the top and 250 μm width on the bottom, is designed and tested. The localization information is derived from the propagation time of the induced signals on the readout strips. This device has a good spatial resolution of 150 μm and works stably at an intensity of 105 Hz/mm2 with 8 keV X-rays.     

Study of measuring methods on spatial resolution of a GEM imaging detector

In this paper, the limitations of the common method measuring intrinsic spatial resolution of the GEM imaging detector are presented. Through theoretical analysis and experimental verification, we have improved the common method to avoid these limitations. Using these improved methods, a more precise measurement of intrinsic spatial resolutions are obtained.     

A novel trilayer antireflection coating using dip-coating technique

We report a new structure for broadband antireflection coating by dip-coating technique, which has minimal cost and is compatible with large-scale manufacturing. The coatings are prepared by depositing SiO 2 sol-gel film on a glass substrate, subsequently depositing SiO 2 single-layer particle coating through electrostatic attraction, and depositing a final very thin SiO 2 sol-gel film to improve the mechanical strength of the whole coating structure. The refractive index of the structure changes gradually from the top to the substrate. The transmittance of a glass substrate has been experimentally found to be improved in the spectral range of 400 1 400 nm and in the incidence angle range from 0 to at least 45 . The mechanical strength is immensely improved because of the additional thin SiO 2 sol-gel layer. The surface texture can be applied to the substrates of different materials and shapes as an add-on coating.     

A large-area photolithography technique based on surface plasmons leakage modes

An atomic force microscope (AFM) assisted surface plasmons leakage radiation photolithography technique has been numerically demonstrated by using two-dimensional finite-difference time-domain (2D-FDTD) method. With the aid of a metallic AFM tip, particular characteristic of the Kretstchmann configuration to excite surface plasmons (SPs) is utilized to achieve large-area patterns with high spatial resolution and contrast, the photoresist could be exposed with low power laser due to the remarkable local field enhancement at the metal/dielectric interface and the resonant localized SPs modes near the tip. Good tolerance on the film thickness and incident angle has been obtained, which provides a good practicability for experiments. This photolithography technique proposed here can realize large-area, high-resolution, high-contrast, nondestructive, arbitrary-structure fabrication of nanoscale devices.     

A novel opto-mechanical uncooled infrared detector

This paper presents a novel opto-mechanical uncooled infrared detector that has successfully been fabricated. The detector is composed of a bi-material micro-cantilever array released from the Si substrate, whose reflector retains its shape even with changes in temperature. In comparison with the generally used sacrificial layer cantilever, the loss of incident IR energy caused by the reflection from and absorption by the silicon substrate is eliminated in this substrate-free structure. Moreover, the freestanding structure of the detector makes it easy to fabricate. The revised reflector in this structure has no distortion during its activity that keeps the sensitivity of the detector from being passivated. We present an infrared (IR) image of a person’s hand to demonstrate the ability of the structure to create images. The performance test showed that the noise-equivalent temperature difference of the imaging system can reach about 175 mK.     

Non-uniformity effects of the inter-foil distance on GEM detector performance

The non-uniformity effect of the inter-foil distance has been studied using a gaseous electron multiplication(GEM) detector with sensitive area of 50mm×50mm. A gradient of the inter-foil distance is introduced by using spacers with different heights at the two ends of the foil gap. While the cluster size and the intrinsic spatial resolution show insignificant dependence on the inter-foil distance, the gain exhibits an approximately linear dependence on the inter-foil distance. From the slope, a quantitative relationship between the change of the inter-foil distance and the change of the gain is derived, which can be used as a method to evaluate the non-uniformity of the foil gap in the application of large-area GEM detectors.     

Study of resolution of the PANDA GEM detector with Garfield

The forward GEM tracker of the P?ANDA detector at the future FAIR facility will track the particles produced in antiproton-proton annihilations and emitted in the polar angle range 5° –22°. Position resolution at the level of 100 μ m and good time resolution are critical to work under luminosities up to 2×10³² c m ^?2 s ^?1. The simulations performed with Garfield program compared several detector layouts and determined the optimal granularity of readout electronics. The time resolution for two possible gas mixtures was also estimated.     

A novel disk-type X-ray area imaging detector using radiophotoluminescence in silver-activated phosphate glass

We report a novel two- and three-dimensional (2-D, 3-D) imaging detector based on the radiophotoluminescence (RPL) phenomenon in silver-activated phosphate glass (PG:Ag) and evaluate its dosimetric characteristics. A compact disk-type PG:Ag detector with a diameter of 80 mm was rotated at a rate of 400 rpm to read out the accumulated dose information and then remove the images for reuse. After X-ray exposure, three RPL dosimeter processes, i.e., preheating, reading, and erasing, were carried out with only a UV laser at 375 nm by adjusting the stepwise output levels. The 3-D images and dose distributions were rapidly reconstructed with a high spatial resolution of 1 μm and a sensitivity of 1 mGy.     

A variable angle photoelectron spectrometer using a position-sensitive detector

A variable angle photoelectron spectrometer utilizing a position-sensitive multidetector is described. Photoelectron spectra of N₂ obtained using a synchrotron radiation source are presented. The data are acquired using a new technique in which the photoelectron yield is obtained as a function of both wavelength and photoelectron energy, and this gives detailed information on autoionization processes.