R. Singaraju

The STAR Photon Multiplicity Detector

Abstract Details concerning the design, fabrication and performance of STAR Photon Multiplicity Detector (PMD) are presented. The PMD will cover the forward region, within the pseudorapidity range 2.3–3.5, behind the forward time projection chamber. It will measure the spatial distribution of photons in order to study collective flow, fluctuation and chiral symmetry restoration.

A honeycomb proportional counter for photon multiplicity measurement in the ALICE experiment

Abstract A honeycomb detector consisting of a matrix of 96 closely packed hexagonal cells, each working as a proportional counter with a wire readout, was fabricated and tested at the CERN PS. The cell depth and the radial dimensions of the cell were small, in the range 5– 10 mm . The appropriate cell design was arrived at using GARFIELD simulations. Two geometries are described illustrating the effect of field shaping. The charged particle detection efficiency and the preshower characteristics have been studied using pion and electron beams. Average charged particle detection efficiency was found to be 98%, which is almost uniform within the cell volume and also within the array. The preshower data show that the transverse size of the shower is in close agreement with the results of simulations for a range of energies and converter thicknesses.

Test and characterization of a prototype silicon–tungsten electromagnetic calorimeter

New generation high-energy physics experiments demand high precision tracking and accurate measurements of a large number of particles produced in the collisions of elementary particles and heavy-ions. Silicon–tungsten (Si–W) calorimeters provide the most viable technological option to meet the requirements of particle detection in high multiplicity environments. We report a novel Si–W calorimeter design, which is optimized for γ/π0 discrimination up to high momenta. In order to test the feasibility of the calorimeter, a prototype mini-tower was constructed using silicon pad detector arrays and tungsten layers. The performance of the mini-tower was tested using pion and electron beams at the CERN Proton Synchrotron (PS). The experimental results are compared with the results from a detailed GEANT-4 simulation. A linear relationship between the observed energy deposition and simulated response of the mini-tower has been obtained, in line with our expectations.

GEM based R&D for muon chambers of CBM experiment at FAIR

A Gas Electron Multiplier (GEM) based detector system has been envisaged for use in a muon tracker in the CBM experiment at FAIR. The choice of the detector technology is mainly guided by the stringent requirements of rate capability and radiation tolerance in the harsh CBM environment, where the particle rates reach upto about 1 MHz/cm2. Several 10 cm × 10 cm triple GEM prototypes have been built at VECC and tested with radioactive sources and with proton and pion/muon beams. Owing to high rate requirements, all the detectors in CBM will have to be operated in a self triggered mode of readout. The readout electronics also have to be appropriately tuned to cater to high rates. A detailed investigation of the self triggered readout electronics including its appropriate setting parameters have been carried out. Prototype tests based on self triggered mode of readout showed a charged particle detection efficiency of more than 90%. The Muon detector modules would employ large area GEM foils. First attempts to stretch and frame large area GEMs, foils of 31 cm × 31 cm have been carried out locally using thermal techniques. A relative gain variation of less than 10% has been observed.

Corrigendum to ‘Measurement of basic characteristics and gain uniformity of a triple GEM detector [Nucl. Instrum. Methods A 862 (2017) 25]’

Erratum Corrigendum to ‘Measurement of basic characteristics and gain uniformity of a triple GEM detector [Nucl. Instrum. Methods A 862 (2017) 25]’ Rajendra Nath Patra a,b, Rama N. Singaraju a, Saikat Biswas c, Zubayer Ahammed a,b, Tapan K. Nayak a,b,d, Yogendra P. Viyogi a a Variable Energy Cyclotron Centre, HBNI, Kolkata-700064, India b Homi Bhabha National Institute, Mumbai-400094, India c Bose Institute, Department of Physics and CAPSS, Kolkata-700091, India d CERN, Geneva 23, Switzerland

Study of a Triple GEM Detector Operated with Different Argon Based Gas

A triple GEM detector of size 10 \(\times \) 10 cm\(^{2}\) has been operated using a Ar:CO\(_{2}\) (90:10) gas mixture. The detector efficiency has been measured with \(^{106}\)Ru-Rh \(\beta \)-source. The gain and energy resolution are measured using the X-ray spectrum of the \(^{55}\)Fe source. The results are compared with those of Ar:CO\(_{2}\) (70:30) gas mixture.

Time Resolution and Characteristic Studies of MWPC Detectors with Argon Based Gas Mixtures

A set of small scale prototypes of Multi-Wire Proportional Chambers (MWPCs) has been fabricated for the study of various characteristics. The detectors have been operated with \(Ar/CO_{2}\) gas mixture in 70:30 and 90:10 ratios. Detector characteristics like efficiency, gain and time resolution have been studied using radioactive sources.

Gain uniformity and characteristics study of a triple GEM detector

Detailed performance study of a 10 × 10 cm2 triple GEM detector operated using a gas mixture of 70% Argon and 30% CO2 has been done with cosmic rays and with 106Ru-Rh β-source. The gain and energy resolution are measured using the X-ray spectrum of the 55Fe source. For the study of the gain uniformity, the active area of the detector is divided into 16 zones and gain is measured in the center of each zone. It is found that the gain variation has an RMS of 6.6%. We also measured the efficiency at the plateau for the 16 zones. The efficiency at the plateau is found to be quite uniform, with an RMS of only 1.9%.

Development of a honeycomb gas proportional counter array for photon multiplicity measurements in high multiplicity environment

A novel gas-based detector using large arrays of honeycomb cells has been developed and tested for use as a pre-shower photon multiplicity detector (PMD) for STAR and ALICE experiments. The appropriate cell design was arrived at using GARFIELD simulations. Prototype chambers with cell dimensions corresponding to STAR and ALICE were fabricated and tested at CERN PS and SPS. The charged particle detection efficiency and the pre-shower characteristics have been studied using pion and electron beams.