Research and development of a gamma-ray imaging spectrometer in the MeV range in Barcelona

Copyright 2010 Society of Photo-Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.Gamma-ray astrophysics in the MeV energy range plays an important role for the understanding of cosmic explosions and acceleration mechanisms in a variety of galactic and extragalactic sources, e.g., Supernovae, Classical Novae, Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, Active Galactic Nuclei (AGN). Through the development of focusing telescopes in the MeV energy range, it will be possible to reach unprecedented sensitivities, compared with those of the currently operating gamma ray telescopes. In order to achieve the needed performance, a detector with mm spatial resolution and very high peak efficiency is required. It will be also desirable that the detector could detect polarization of the source. Our research and development activities in Barcelona aim to study a gamma-ray imaging spectrometer in the MeV range suited for the focal plane of a gamma-ray telescope mission, based on CdTe pixel detectors arranged in multiple layers with increasing thicknesses, to enhance gamma-ray absorption in the Compton regime. We have developed an initial prototype based on several CdTe module detectors, with 11x11 pixels, a pixel pitch of 1mm and a thickness of 2mm. Each pixel is stud-bump bonded to a fanout board and routed to a readout ASIC to measure pixel position, pulse height and rise time information for each incident gamma-ray photon. We will report on the results of an optimization study based on simulations, to select the optimal thickness of each CdTe detector within the module to get the best energy resolution of the spectrometer.Peer reviewe

Characterization and simulation of a CdTe detector for use in PET

The Voxel Imaging PET (VIP) Path nder project got the 4 year European Research Council FP7 grant in 2010 to prove the feasibility of using CdTe detectors in a novel conceptual design of PET scanner. The work presented in this thesis is a part of the VIP project and consists of, on the one hand, the characterization of a CdTe detector in terms of energy resolution and coincidence time resolution and, on the other hand, the simulation of the setup with the single detector in order to extend the results to the full PET scanner. An energy resolution of 0.98% at 511 keV with a bias voltage of 1000 V/mm has been measured at low temperature T=-8 ºC. The coincidence time distribution of two twin detectors has been found to be as low as 6 ns FWHM for events with energies above 500 keV under the same temperature and bias conditions. The measured energy and time resolution values are compatible with similar ndings available in the literature and prove the excellent potential of CdTe for PET applications. This results have been presented in form of a poster contribution at the IEEE NSS/MIC & RTSD 2011 conference in October 2011 in Valencia and at the iWoRID 2012 conference in July 2012 in Coimbra, Portugal. They have been also submitted for publication to "Journal of Instrumentation (JINST)" in September 2012

Determination of alpha(s) using energy-energy correlation asymmetry and jet mass difference at MARK II/SLC.

The determination of the strong coupling constant \alpha\sb s, using Energy-Energy Correlation Asymmetry and jet mass difference with Mark II data at SLC (91 GeV) is presented. In Energy-Energy Correlation Asymmetry (EECA), we used the same systematic procedure used to determine \alpha\sb s with MARK II data at PEP (29 GeV). The \chi\sp2 fit suggests that \alpha\sb s = 0.119 $\pm$ 0.007(stat.) $\pm$ 0.007(syst.). In addition, we used the EECA method to determine the QCD scale parameter \Lambda\sb{LLA}. The \chi\sp2 fit suggests that \Lambda\sb{LLA} = 420 $\pm$ 90(stat.) MeV. In the jet mass difference method, the determination of \alpha\sb s is based on QCD calculations up to 2nd order. We showed that in this method we are able to reproduce the value of \alpha\sb s from a Monte Carlo sample to a very high accuracy. The result with this method is \alpha\sb s = 0.134 $\pm$ 0.085(stat.) $\pm$ 0.004(syst.). The two values of \alpha\sb s presented in this work are in agreement within the error bars and in a good agreement with recent results of \alpha\sb s published from other e\sp+e\sp- experiments.Ph.D.PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/105354/1/9123993.pdfDescription of 9123993.pdf : Restricted to UM users only

Sistema digital para realizar biopsia estereotáxica

Referencia OEPM: P200401878 .-- Fecha de solicitud: 29/07/2004.-- Titulares: Udiat Centre Diagnostic, S.A., Institut de Fisica d'Altes Enerties (IFAE), Consejo Superior de Investigaciones Científicas (CSIC).Sistema digital para realizar biopsias estereotáxicas con una aguja de biopsia, comprendiendo dicho sistema una serie de dispositivos para: emitir rayos X, detectar y transformar fotones de rayos X en señales eléctricas, posicionar una muestra de tejido entre la fuente de rayos X y el detector, procesar las señales eléctricas y generar imágenes. El sistema bien puede disponer de una serie de dispositivos complementarios a los mencionados, bien puede disponer de unos medios de posicionamiento para situar en dos posiciones los dispositivos mencionados y obtener imágenes según dos orientaciones.Peer reviewe

Sistema digital para realizar biopsia esterotáxica.

Filing Date: 2005-07-27.--Priority Data: ES P200401878 (2004-07-29)The invention relates to a digital system (1) for performing stereotaxic biopsies with a biopsy needle. The inventive system (1) comprises a series of devices which are used to: emit X-rays, detect and transform X-ray photons into electric signals, position a tissue sample between the X-ray source and the detector, process the electric signals, and generate images. The system can also be equipped with a series of devices complementary to those mentioned above, as well as a means for positioning the aforementioned devices in two positions and obtaining images in two different orientations

Measurement of mobility and lifetime of electrons and holes in a Schottky CdTe diode

We report on the measurement of drift properties of electrons and holes in a CdTe diode grown by the travelling heating method (THM). Mobility and lifetime of both charge carriers has been measured independently at room temperature and fixed bias voltage using charge integration readout electronics. Both electrode sides of the detector have been exposed to a 241 Am source in order to obtain events with full contributions of either electrons or holes. The drift time has been measured to obtain the mobility for each charge carrier. The Hecht equation has been employed to evaluate the lifetime. The measured values for μτ (mobility-lifetime product) are in agreement with earlier published data

Imaging detector development for nuclear astrophysics using pixelated CdTe

1st International Conference on Technology and Instrumentation in Particle PhysicsThe concept of focusing telescopes in the energy range of lines of astrophysical interest (i.e., of energies around 1 MeV) should allow to reach unprecedented sensitivities, essential to perform detailed studies of cosmic explosions and cosmic accelerators. Our research and development activities aim to study a detector suited for the focal plane of a γ-ray telescope mission. A CdTe/CdZnTe detector operating at room temperature, that combines high detection efficiency with good spatial and spectral resolution is being studied in recent years as a focal plane detector, with the interesting option of also operating as a Compton telescope monitor. We present the current status of the design and development of a γ-ray imaging spectrometer in the MeV range, for nuclear astrophysics, consisting of a stack of CdTe pixel detectors with increasing thicknesses. We have developed an initial prototype based on CdTe ohmic detector. The detector has 11×11 pixels, with a pixel pitch of 1 mm and a thickness of 2 mm. Each pixel is stud bonded to a fanout board and routed to an front end ASIC to measure pulse height and rise time information for each incident γ-ray photon. First measurements of a 133Ba and 241Am source are reported here.Peer reviewe

Characterization and simulation of a CdTe detector for use in PET

The Voxel Imaging PET (VIP) Path nder project got the 4 year European Research Council FP7 grant in 2010 to prove the feasibility of using CdTe detectors in a novel conceptual design of PET scanner. The work presented in this thesis is a part of the VIP project and consists of, on the one hand, the characterization of a CdTe detector in terms of energy resolution and coincidence time resolution and, on the other hand, the simulation of the setup with the single detector in order to extend the results to the full PET scanner. An energy resolution of 0.98% at 511 keV with a bias voltage of 1000 V/mm has been measured at low temperature T=-8 ºC. The coincidence time distribution of two twin detectors has been found to be as low as 6 ns FWHM for events with energies above 500 keV under the same temperature and bias conditions. The measured energy and time resolution values are compatible with similar ndings available in the literature and prove the excellent potential of CdTe for PET applications. This results have been presented in form of a poster contribution at the IEEE NSS/MIC & RTSD 2011 conference in October 2011 in Valencia and at the iWoRID 2012 conference in July 2012 in Coimbra, Portugal. They have been also submitted for publication to "Journal of Instrumentation (JINST)" in September 2012