Oscar Martínez

Search for Gamma Ray Bursts at Sierra Negra, México

We present results from a search for GRBs in the energy range from tens of GeVs to one TeV with an array of 4 water Cherenkov detectors located at 4550 m a.s.l. as part of the high mountain observatory of Sierra Negra (N18°59.1, W97°18.76) near Puebla city in Mexico. The detectors consist of light‐tight cylindrical containers of 1 m2 and 4 m2 cross section filled with purified water; they are spaced 25 m and have a 5″ photomultiplier (EMI model 9030A) facing down along the cylindrical axis. We report the measured rates of the electromagnetic and mounic components of the background as the photon estimated flux.

High Density Devices Applied to a Gamma-Camera Implementation

Image processing is considered to be one of the most rapidly evolving areas of information technology, with growing applications in all fields of knowledge. It constitutes a core area of research within the computer science and engineering disciplines given the interest of potential applications ranging from image enhancing, to automatic image understanding, robotics and computer vision. The performance requirements of image processing applications have continuously increased the demands on computing power, especially when there are real time constraints. Image processing applications may consist of several low level algorithms applied in a processing chain to a stream of input images. In order to accelerate image processing, there are different alternatives ranging from parallel computers to specialized ASIC architectures. The computing paradigm using reconfigurable architectures based on Field Programmable Gate Arrays (FPGAs) promises an intermediate trade-off between flexibility and performance.

Hybrid Extensive Air Shower Detector Array at the University of Puebla to Study Cosmic Rays

We describe the design of an extensive air shower detector array built in the Campus of the University of Puebla (located at 19◦N, 90◦W, 800 gcm−2) to measure the energy and arrival direction of primary cosmic rays with energies around 10 eV. The array consists of 18 liquid scintillator detectors (12 in the first stage) and 6 water Cherenkov detectors (one of 10 m cross section and five smaller ones of 1.86 m cross section), distributed in a square grid with a detector spacing of 20 m over an area of 4000 m. In this paper we discuss the calibration and stability of the array, and discuss the capability of hybrid arrays, such as this one consisting of water Cherenkov and liquid scintillator detectors, to allow a separation of the electromagnetic and muon components of extensive air showers. This separation plays an important role in the determination of the mass and identity of the primary cosmic ray. This facility is also used to train students interested in the field of cosmic rays.

CHARM Observatory Status and performance

CHARM, Cosmic High Altitude Radiation Monitor, is an observatory whose target is the study of cosmic rays. This is actually under construction stage, it consists of an array of Water Cherenkov Detectors (WCD) located in Puebla Mexico, at 18.591N and 97.1876W, 4300 meters over sea level. Each WCD container inner walls is covered inside with a high UV reflective material called Tyvek, and it is filled with 12000 liters of pure water. The WCD has a sensitive area of 10 m², and the Photomultiplier inside (PMT) is an EMI 9530A (PMT), which has the acquisition electronic associated too. The observatory is designed to study high-energy cosmic rays in the range 1 PeV – 100 PeV. This work presents the actual status, the temporal structure signals (peak amplitude and integrated charge) and the stability of the Water Cherenkov Detectors. This study is performed using secondary particles from the background.

Auger Prime the new stage of the Pierre Auger Observatory, using Universality

The Pierre Auger Observatory is currently in an update stage denominated AugerPrime. The Observatory will have scintillator detectors on top of each of the surface stations (WCD). The main goal of AugerPrime is to improve the studies on mass composition for ultra high energy cosmic rays, for this purpose AugerPrime will use Universality. The model will parameterize the signal in four principal components, the objective is an adequate discrimination of the muonic and electromagnetic components. We are interested in the discrimination of these two components using simulations. To do that, we are working with OfflineTrunk (the official software of the Collaboration). Our work is focused on the development of some modules for analysis and study of the signal from AugerPrime.

Description of a4 -channel FPGA-controlled ADC-based DAQ system for general purpose PMT signals

We describe a general purpose data acquisition system for PMT signals. Hardware-wise it consists of a 4-channel ADC daughter board, an FPGA mother board, a GPS receiver and an atmospheric pressure sensor and a temperature sensor. The four ADC channels simultaneously sample PMT input signals with a sampling rate of 100MS/s. We have evaluated the noise of our system obtaining less than -48.6dB. This DAQ system includes a firmware suitable for pulse processing in cosmic rays applications. In particular, we describe in detail the way in which this system can be used during the commissioning and early operation phases of the High Altitude Water Cherenkov Observatory (HAWC) currently under construction at Sierra Negra in Mexico.

Image reconstruction FPGA prototype applied to a mini gamma camera

In this work a read out electronics prototype for reconstruction of two-dimensional images based on Field Programmable Gate Arrays (FPGAs) is presented. The front-end includes two main modules, the data acquisition electronics and a hardware architecture for data processing. The read out electronics consists mainly of a Resistive Chain, analog-to-digital converters and a FPGA Virtex IV of the Xilinxs family. This module reads the electrical signals produced by a position-sensitive photomultiplier tube (PS-PMT) coupled to a cerium-doped lutetium yttrium orthosilicate (LYSO) crystal. The hardware architecture takes the digitized signals produced by the acquisition module and processes them to determine the position of the interactions based on the Anger logic to form a planar image. The hardware architecture performs arithmetic operations, formats and stores the data in order to send them to the displaying stage. The resulting image represents a 2D histogram for the intensity distribution of the radioactivity. Both systems interact to operate at a clock frequency of 322 MHz reducing the processing time to reach real time performance. Using parallel techniques and an appropriate management of memory, the necessary logic to implement the system has been developed improving flexibility for adjustment to new requirements or new algorithms. The main contribution of this work consists on validating the use of a FPGA in the image processing stage in a nuclear medicine application, such as the Gamma Camera.

Electronics for the Extensive Air Shower Detector Array at the University of Puebla

In this paper we describe in detail the electronics cards that were designed to be the basis of the data acquisition system (DAS) of the extensive air shower detector array built in the Campus of the University of Puebla. The purpose of this observatory is to measure the energy and arrival direction of primary cosmic rays with energies around 1015 eV. The array consists of 18 liquid scintillator detectors (12 in the first stage) and 6 water Cherenkov detectors (one of 10 m2 cross section and five smaller ones of 1.86 m2 cross section), distributed in a square grid with a detector spacing of 20 m over an area of 4000 m2. The electronics described here uses analog to digital converters of 10 bits working at a sampling speed of 40 MS/s and field‐programmable gate array (FPGA).

Getting the Traces (FADCs) of a Water Cherenkov Detector Signal

In this work we present the electronics developed into a complete data acquisition system (DAS) for a water Cherenkov detector (WCD) in order to detect cosmic rays with energies from 1 × 1014 to 1 × 1016 eV. The components are: a high voltage source, a bleeder circuit for each photomultiplier, an electronic unit to amplify, compare, determine coincidence and sum the signals produced by the PMTs, a control circuit to digitalize and store the information corresponding to a valid event and finally an interface to a PC to record data for further analysis. The sampling rate of the system is 40 MHz.

Extensive Air Shower Detector Array at the Universidad Autonoma de Puebla

We describe the operation of an Extensive Air Shower Array located at the campus of the FCFM‐BUAP. The array consists of 8 liquid scintillation detectors with a surface of 1 m2 each and a detector spacing of 20 m in a square grid. The array was designed to measure the energy and arrival direction of primary particles that generate extensive air showers (EAS) in the region of 1013 eV – 1016 eV. The angular distribution measured with this array, Cos8(Θ)×Sin(Θ), agrees very well with the literature. We also present the measured energies of a number of vertical showers in the range of 5×1012 eV to 5×1013 eV.