A Novel Nanowire Metal Converter for Improvement the Efficiency of the Gas-filled Radiation Detectors

Metal nanowires, due to their special physical properties and also high surface to volume ratio, can have considerable applications in designing and development of novel nano devices. For the radiation shielding, higher absorption coefficient of nano structures in comparison to bulk ones is an advantage. In gas detectors, designing a proper converter with higher efficiency which absorbs higher energy of gamma and X-rays and convert it to free electrons is one of the major requirements. Since the nano wires have higher surface to volume ratio in comparison to the bulk ones, so it is expected that with the same thickness, the generated electrons have higher chance to escape from the surface. In this work, the random Copper nanowires with diameter of 40 nm are deposited on very thin glass slide. This nano structure with thickness of 30 μm is tested with X-rays energy between 12 to 22 keV. The results clearly show that this nano structure for the energy of 20 keV can release electrons three times more than the bulk ones. This novel nanoconverter with higher quantum efficiency can have many applications in high energy physics, medical imaging, and astronomy

Characterization of a thick layer a-Si : H pixel detector with TFA technology using a scanning electron microscope

The electron beam induced current (EBIC) technique was used to characterize a 32 μm thick hydrogenated amorphous silicon n-i-p diode deposited on top of an ASIC, containing several channels of active feedback pre-amplifiers (AFP) with peaking time of 5 ns. The homogeneity of the sample together with the edge effects induced by the unevenness of the ASIC substrate were studied with low doses of 10-30 keV electron beam. The degradation of a-Si:H pixel detectors was measured with intense electron beam. Their charge collection and transient time were characterized with a 660 nm pulsed laser before and after the thermal annealing. All the diodes show approximately a full recovery of charge collection after thermal annealing. © 2006 Elsevier B.V. All rights reserved

Hydrogenated amorphous silicon sensors based on thin film on ASIC technology

The performance and limitations of a novel detector technology based on the deposition of a thin-film sensor on top of processed integrated circuits have been studied. Hydrogenated amorphous silicon (a-Si:H) films have been deposited on top of CMOS circuits developed for these studies and the resulting "thin-film on ASIC" (TFA) detectors are presented. The leakage current of the a-Si:H sensor at high reverse biases turns out to be an important parameter limiting the performance of a TFA detector. Its detailed study and the pixel segmentation of the detector are presented. High internal electric fields (in the order of 10/sup 4/-10/sup 5/ V/cm) can be built in the a-Si:H sensor and overcome the low mobility of electrons and holes in a-Si:H. Signal induction by generated carrier motion and speed in the a-Si:H sensor have been studied with a 660 nm pulsed laser on a TFA detector based on an ASIC integrating 5 ns peaking time pre- amplifiers. The measurement set-up also permits to study the depletion of the sensor and results are presented. Finally, direct detection of 5.9 keV X-rays with TFA detectors based on an ASIC integrating low noise pre-amplifiers (27 e/sup negative r.m.s.) are shown

Diffraction and Total Cross-Section at the Tevatron and the LHC

At the Tevatron, the total p_bar-p cross-section has been measured by CDF at 546 GeV and 1.8 TeV, and by E710/E811 at 1.8 TeV. The two results at 1.8 TeV disagree by 2.6 standard deviations, introducing big uncertainties into extrapolations to higher energies. At the LHC, the TOTEM collaboration is preparing to resolve the ambiguity by measuring the total p-p cross-section with a precision of about 1 %. Like at the Tevatron experiments, the luminosity-independent method based on the Optical Theorem will be used. The Tevatron experiments have also performed a vast range of studies about soft and hard diffractive events, partly with antiproton tagging by Roman Pots, partly with rapidity gap tagging. At the LHC, the combined CMS/TOTEM experiments will carry out their diffractive programme with an unprecedented rapidity coverage and Roman Pot spectrometers on both sides of the interaction point. The physics menu comprises detailed studies of soft diffractive differential cross-sections, diffractive structure functions, rapidity gap survival and exclusive central production by Double Pomeron Exchange.At the Tevatron, the total p_bar-p cross-section has been measured by CDF at 546 GeV and 1.8 TeV, and by E710/E811 at 1.8 TeV. The two results at 1.8 TeV disagree by 2.6 standard deviations, introducing big uncertainties into extrapolations to higher energies. At the LHC, the TOTEM collaboration is preparing to resolve the ambiguity by measuring the total p-p cross-section with a precision of about 1 %. Like at the Tevatron experiments, the luminosity-independent method based on the Optical Theorem will be used. The Tevatron experiments have also performed a vast range of studies about soft and hard diffractive events, partly with antiproton tagging by Roman Pots, partly with rapidity gap tagging. At the LHC, the combined CMS/TOTEM experiments will carry out their diffractive programme with an unprecedented rapidity coverage and Roman Pot spectrometers on both sides of the interaction point. The physics menu comprises detailed studies of soft diffractive differential cross-sections, diffractive structure functions, rapidity gap survival and exclusive central production by Double Pomeron Exchange