Nuclear science

We propose precise and fast-track reconstruction at hadron collider experiments, for use in online trigger decisions. We describe the features of fast-track (FTK), a highly parallel processor dedicated to the efficient execution of a fast-tracking algorithm. The hardware-dedicated structure optimizes speed and size; these parameters are evaluated for the ATLAS experiment. We discuss some applications of high-quality tracks available to the trigger logic at an early stage, by using the LHC environment as a benchmark. The most interesting application is online selection of b-quarks down to very low transverse momentum, providing interesting hadronic samples: examples are Z 0 b b, potentially useful for jet calibration, and multi-b final states for supersymmetric Higgs searches. The paper is generated from outside the ATLAS experiment and has not been discussed by the ATLAS collaboration.

Recent progress in advanced digital signal processing provides an opportunity to expand the computation power required for real time extraction of event characteristics in avalanche photodiode (APD)-based Positron Emission Tomography (PET) scanners. These developments are made possible by a highly parallel data acquisition (DAQ) system based on an integrated analog front-end and a high-speed fully digital signal processing section that directly samples the output of each preamplifier with a free-running, off-the-shelf, 45-MHz analog-to-digital converter that feeds the sampled data into a field programmable gate array (FPGA) VirtexII PRO from Xilinx. This FPGA features 31 000 logic cells and two PowerPC processors, which allows up to 64 channels to be processed simultaneously. Each channel has its own digital signal processing chain including a trigger, a baseline restorer and a timestamp algorithm. Various timestamp algorithms have been tested so far, achieving a coincidence timing resolution of 3.2-ns full-width at half-maximum (FWHM) for APD coupled to Lutetium Oxyorthosilicate (APD-LSO) and 11.4-ns FWHM for APD coupled to Bismuth Germanium Oxide (APD-BGO) detectors, respectively. Channels are then multiplexed into a DSP processor from Texas Instruments for crystal identification by an ARMAX recursive algorithm borrowed from identification and vector quantization theory. The system can sustain an event rate of 10 000 events/s/channel without electronic dead time. Index Terms-Avalanche photodiodes (APDs), field programmable gate array (FPGA), Positron Emission Tomography (PET), real time digital signal processing.

This paper presents in phantom testing of a recently developed intraoperative minidosimetry system, designed to measure the dose along the urethra during low dose rate prostate brachytherapy. This system is based on a silicon minidetector and uses spectroscopy to calculate the localized dose from the treatment radiation. The minidosimetry system was demonstrated to be operational at body temperature, with a near isotropic response to radiation at all angles. Phantom measurements have shown the minidosimetry system to measure the dose from multiple seeds to within 5% of planning system calculated doses. This system is an ideal complement to ultrasound guided seed placement in providing online direct dosimetry during seed implantation, as well as providing dose planning system verification through post implant dosimetry.

A set of physics models and parameters pertaining to the simulation of proton energy deposition in matter are evaluated in the energy range up to approximately 65 MeV, based on their implementations in the Geant4 toolkit. The analysis assesses several features of the models and the impact of their associated epistemic uncertainties, i.e. uncertainties due to lack of knowledge, on the simulation results. Possible systematic effects deriving from uncertainties of this kind are highlighted; their relevance in relation to the application environment and different experimental requirements are discussed, with emphasis on the simulation of radiotherapy setups. By documenting quantitatively the features of a wide set of simulation models and the related intrinsic uncertainties affecting the simulation results, this analysis provides guidance regarding the use of the concerned simulation tools in experimental applications; it also provides indications for further experimental measurements addressing the sources of such uncertainties.

Abstract--The experimental environment of the Virgo project is briefly described. We present the current hardware and software architecture of the data acquisition system. Particular emphasis will be given to the timing system used to synchronize the various readouts and controls around the interferometer and to the distributed data collection scheme: its flexibility, modularity and processing capabilities.

Geant4 is a general purpose and open source C++ Monte Carlo simulation toolkit, widely used in the scientific community. It is able to simulate physical interactions of particles through matter. According to the user's needs, models for the simulation of electromagnetic (EM) interactions are provided in two Geant4 subpackages, the 'standard' EM subpackage, well suited for a wide range of applications and the 'low-energy' EM subpackage, able to reach the electronVolt regime. Particle-induced X-ray emission (PIXE) is a well known and a very useful technique for quantitative elemental analysis in environmental, archaeological, biological, medical and space applications. An atomic de-excitation module is part of the Geant4 'low-energy' EM subpackage since 1999 and has been validated in recent years. PIXE simulation has been included in this subpackage in 2001 and new ionisation cross-sectional models following the ECPSSR theory have been added for the PIXE simulation in 2008. In 2010, these models have been further extended to higher energies. In this work, we present new results on the verification of these models and an overview of the new interface to PIXE modelling prepared for the recent public release of the Geant4 toolkit (December 2010) allowing a unified usage of the Geant4 de-excitation module by both 'standard' and 'low-energy' subpackages. Copyright

The presence of defects in Cl-doped CdTe crystals influences the electrical properties and the homogeneity of the material. The aim of this paper is to study the effects of thermal treatment on the precipitates present in the volume of the material and thus on the uniformity of the material in regards to both resistivity and precipitate concentrations. The samples are annealed under argon pressure. The number of precipitates, generally of Te, is measured using infrared microscopy. In addition, a low-cost contactless measurement technique for resistivity mapping has been developed. This technique presents a good spatial resolution of approximately 1 mm and a resistivity range measurement of 10 6-10 10-cm. The relation between the number of Te-precipitates and the resistivity maps is investigated. A decrease in the number of Te-precipitates after sample annealing is observed. Furthermore, the resistivity decreases with an increase in the number of precipitates in the material. The uniformity of the annealed samples is discussed. The correlation of the resistivity maps and the Te-precipitates is also given, illustrated by comparison topography with resistivity and Te-precipitate concentrations. The contactless resistivity measurement technique is also described.

CdTe crystals grown by the traveling heater method (THM) often show a pronounced nonuniformity along the ingots due to the thermal irregularities, the Te-excess growth conditions resulting from the retrograde slope of the solidus line of the phase diagram, and from the introduced impurities. In addition, structural defects can be present that influence the electrical and optical properties. The aim of this work is to study the annealing effects of Cl-doped CdTe on the uniformity of the material, the defects, the resistivity, the product, and on the detection properties. Samples have been annealed under various pressures (vacuum, argon, CdCl 2) and include different temperature stages between 250 C and 850 C. An increase of the resistivity was observed after a thermal treatment of these samples under argon pressure. In this case, the highest resistivity was obtained by annealing samples at 460 C. The presence of CdCl 2 during the annealing leads to a better uniformity of the materials. The defects present in the materials have been investigated by photo-induced transient current spectroscopy (PICTS), thermoelectric emission spectroscopy (TEES), and thermally stimulated current (TSC) methods, which allow the calculation of their activation energy, their cross section, and their concentration. A strong correlation between the 0.6 and 0.76 eV levels and the measured resistivity has been observed. The effects of the other levels on the electrical properties is described. A discussion about the origin of these defects and a comparison with obtained results by the above methods is then given.

Europium isotope effects in the Eu(II)/ Eu(II1) electron exchange system (EXS) has been studied by means of cation exchange chromatography in the temperature range 308-343 K. The heavier isotope lS3Eu was enriched at the front part of the europium band, and the values of the observed single stage separation coefficients (~= a-l) , of the 1 5 3 E~/ 1 5 1 E~ isotopic pair, increased with the increase in temperature as l. l~l O-~, l. Z~l o-~, Z .~X~O-~, and 2. 4~1 0~~ at 308K, 323K, 333K, and 343K, respectively. Based on the experimental data, the logarithm of the isotopic equilibrium constant, In K = E~, of Eu(II)/Eu(III) electron exchange system have been calculated. The chromatographic height equivalent to a theoretical plate, HETP, was also calculated and found to decrease with temperature.

As part of a program to investigate the feasibility of proton computed tomography, the most likely path (MLP) of protons inside an absorber was measured in a beam experiment using a silicon strip detector setup with high position and angular resolution. The locations of 200 MeV protons were measured at three different absorber depth of PolyMethylMethAcrylate-PMMA (3.75, 6.25 and 12.5 cm) and binned in terms of the displacement and the exit angle measured behind the absorber. The observed position distributions were compared to theoretical predictions showing that the location of the protons can be predicted with an accuracy of better than 0.5 mm.

Proton therapy is a precise forms of radiation therapy that makes use of high energy proton compared to the conventional, more commonly used and less precise x-ray and electron beams. On the other hand, to fully exploit the proton therapy advantages, very accurate quality controls of the treatments are required. These are mainly related to the dose calculations and treatment planning. Actually dose calculations are routinely performed on the basis of X-Ray computed tomography while a big improvement could be obtained with the direct use of protons as the imaging system. In this work we report the results of Monte Carlo simulations for the study of an imaging system based on the use of high energy protons: the proton Computed Tomography (pCT). The main limitation of the pCT and the current adopted technical solutions, based on the use of the Most Likely Path (MLP) approximation are illustrated. Simulation results are compared with experimental data obtained with a first prototype of pCT system tested with 200 MeV proton beams available at the Loma Linda University Medical Center (LLUMC) (CA).

This paper describes the design features of a ,f data readout system for multi-wire proportional chambers. The electronic circuitry for this "amplifier-per-\~ire" system has been designed in modular form to provide. ease in system assembly, flexibility, and economy. Fast readout of the hit-pattern data is accomplished by using priority encoder inte-C1rated circuits for addreSS generation and bit-parallel transfer of the outp~t data words. About 7000 channels have been implemented using this system and an additional 4000 channels have been ordered, An analysis• of cost per channel is given, based on the experience gained thus far.

The aim of the work is to design and describe the methodology of determination of the spatial weighting function of ex-core detectors for the WWER-440 reactor type using Monte Carlo N-Particle Transport code MCNP-4C2, taking into account the different operational parameters such as power, burn-up, boric acid concentration and position of control assembly group No 6. The spatial weight function provides relationship between the spatial neutron flux density distribution or the fission density distribution in the reactor core and the detectors placed outside of the reactor core (ex-core detectors). The spatial weight function will be used for interpretation of reloads startup rod drop measurements, assessment of the ex-core detectors response at deep subcritical reactor stage and for other applications.

Abstract—Particle induced X-ray emission (PIXE) is an impor-tant physical effect that is not yet adequately modelled in Geant4. This paper provides a critical analysis of the problem domain associated with PIXE simulation and describes a set of software developments to improve PIXE simulation with Geant4. The capabilities of the developed software prototype are illustrated and applied to a study of the passive shielding of the X-ray detectors of the German eROSITA telescope on the upcoming Russian Spectrum-X-Gamma space mission. Index Terms—Monte Carlo, Geant4, PIXE, ionization. I.

We previously developed a realistic phantom for the cardiac motion for use in medical imaging research. The phantom was based upon a gated magnetic resonance imaging (MRI) cardiac study and using 4D non-uniform rational b-splines (NURBS). Using the gated MRI study as the basis for the cardiac model had its limitations. From the MRI images, the change in the size and geometry of the heart structures could be obtained, but without markers to track the movement of points on or within the myocardium, no explicit time correspondence could be established for the structures. Also, only the inner and outer surfaces of the myocardium could be modeled. We enhance this phantom of the beating heart using 4D tagged MRI data. We utilize NURBS surfaces to analyze the full 3D motion of the heart from the tagged data. From this analysis, time-dependent 3D NURBS surfaces were created for the right (RV) and left ventricles (LV). Models for the atria were developed separately since the tagged data only covered the ventricles. A 4D NURBS surface was fit to the 3D surfaces of the heart creating time-continuous 4D NURBS models. Multiple 4D surfaces were created for the left ventricle (LV) spanning its entire volume. The multiple surfaces for the LV were spline-interpolated about an additional dimension, thickness, creating a 4D NURBS solid model for the LV with the ability to represent the motion of any point within the volume of the LV myocardium at any time during the cardiac cycle. Our analysis of the tagged data was found to produce accurate models for the RV and LV at each time frame. In a comparison with segmented structures from the tagged dataset, LV and RV surface predictions were found to vary by a maximum of 1.5 mm's and 3.4 mm's respectively. The errors can be attributed to the tag spacing in the data (7.97 mm's). The new cardiac model was incorporated into the 4D NURBS-based Cardiac-Torso (NCAT) phantom widely used in imaging research. With its enhanced abilities, the model will provide a useful tool in the study of cardiac imaging and the effects of cardiac motion in medical images.

Patient motion during cardiac SPECT imaging can cause diagnostic imaging artifacts. We investigated the feasibility of monitoring patient motion using the Polaris motion-tracking system. This system uses passive infrared reflection from small spheres to provide real-time position data with vendor stated 0.35 mm accuracy and 0.2 mm repeatability. In our configuration, the Polaris system views through the SPECT gantry toward the patient's head. List-mode event data was temporally synchronized with motion-tracking data utilizing a modified LabVIEW virtual instrument that we have employed in previous optical motion-tracking investigations. Calibration of SPECT to Polaris coordinates was achieved by determining the transformation matrix necessary to align the position of four reflecting spheres as seen by Polaris, with the location of Tc-99m activity placed inside the sphere mounts as determined in SPECT reconstructions. We have successfully tracked targets placed on volunteers in simulated imaging positions on the table of our SPECT system. We obtained excellent correlation (R 2 > 0.998) between the change in location of the targets as measured by our SPECT system and the Polaris. We have also obtained excellent agreement between the recordings of the respiratory motion of four targets attached to an elastic band wrapped around the abdomen of volunteers and from a pneumatic bellows. We used the axial motion of point sources as determined by the Polaris to correct the motion in SPECT image acquisitions yielding virtually identical point source FWHM and FWTM values, and profiled maximum heart wall counts of cardiac phantom images, compared to the reconstructions with no motion.

A fully digital data acquisition (DAQ) system [1,2] for a cylindrical (NaI(T1)) SPECT camera has been developed and tested. This system digitizes pulses of the scintillation e vents from the closest (7 or 5) PMTs to the interaction point. The digitized pulse waveforms are processed to obtain estimates of amplitude and time of arrival. We describe various processing methods based on both simulated and real data. The results obtained from a set of three neighboring PMTs using 99""rc was 5.2 ns std. dev. in timing resolution, 12.6% energy resolution and the computing time per pulse about 7 ps.

We have constructed a prototype, rapid-deployment portal monitor that uses visible-light and gamma-ray imaging to allow simultaneous monitoring of multiple lanes of traffic from the side of a roadway. Our Roadside Tracker uses automated target acquisition and tracking (TAT) software to identify and track vehicles in visible light images. The field of view of the visible camera overlaps with and is calibrated to that of a one-dimensional gamma-ray imager. The TAT code passes information on when vehicles enter and exit the system field of view and when they cross gamma-ray pixel boundaries. Based on this information, the gamma-ray imager "harvests" the gamma-ray data specific to each vehicle, integrating its radiation signature for the entire time that it is in the field of view. In this fashion we are able to generate vehicle-specific radiation signatures and avoid source confusion problems that plague nonimaging approaches to the same problem.

A miniature scintillation camera with a 5 cm 5 cm field-of-view (FOV) is being developed to aid in surgical staging of cancer. This paper reports on certain interesting design aspects of the scintillation crystal array. Simulations and measurements of different types of crystal materials revealed that lutetium oxyorthosilicate (LSO), which is ordinarily used in PET, has appealing properties for detecting 140 keV photons. For example, LSO requires only 3 mm of thickness for 95% detection efficiency at 140 keV. This small thickness is appealing for high light collection efficiency, narrow light distribution, and minimizing the LSO volume in order to reduce intrinsic background events produced by 176 Lu (2.6% abundance). Studies of both discrete and sheet crystals revealed that discrete crystal arrays have the advantage of increased spatial linearity and dynamic range compared to crystal sheets. For optimizing sensitivity and spatial resolution, several crystal array conditions were investigated, including ground crystal pixels packed tightly together with internal reflectors and with optical coupling grease. This design focuses the light, but also allows adequate light sharing for positioning with the position sensitive photomultiplier tube (PSPMT) that will be used in the gamma camera.

A system test of various components of the Solenoidal Tracker at RHIC (STAR) detector, operating in concert, has recently come on-line. Communication between a major sub-detector, a sector of the Time Projection Chamber (TPC), and the trigger, data acquisition and slow controls systems has been established, enabling data from cosmic ray muons to be collected. First results from an analysis of the TPC data are presented. These include measurements of system noise, electronic parameters such as amplifier gains and pedestal values, and tracking resolution for cosmic ray muons and laser induced ionization tracks. A discussion on the experience gained in integrating the different components for the system test is also given.

The Fast Track processor (FTK) has been proposed for high-quality track finding at very high rates (Level-1 output rates) for the LHC experiments. Fast, efficient and precise pattern recognition has been studied using a silicon 7-layer sub-detector, including a subset of the pixel and SCT layers. We tested the FTK algorithms using the ATLAS full simulation. We compare the FTK reconstruction quality with the tracking capability of the offline iPatRec algorithm. We show that similar resolutions and efficiencies are reached by FTK at a speed higher than iPatRec by orders of magnitude. With FTK full events are reconstructed at the Level-1 output rate. 0 + events are fully simulated together with background samples. We show that a low Level-2 rate is allowed by FTK, even using a single 6 GeV Level-1 muon selection trigger. FTK provides the full-resolution track list ready for the Level-2 0 identification. All selection cuts performed by the Event Filter can be easily anticipated at Level-2. We present the 0 + efficiency gain and related Level-2 rates.

The most frequently used radiopharmaceutical for treatment of thyroid cancer is the radioactive iodine (RAI). Patients treated with RAI therapy cause risk of external radiation exposure to the public and family members. While the therapeutic use of iodine-131 for thyroid carcinoma patients offers enormous benefit to them, it contributes also significantly to the radiation exposure of individuals and population. Patients treated with radioiodine present a radiation hazard and precautions are necessary to limit radiation dose to the relatives and the members of the public. The study aims to develop guidelines for the release of thyroid cancer patients treated with I-131. For this purpose, simulations were performed for estimating suitable period of restriction during which close contact with the patient should be disallowed and limited. These simulations are based on the French working Group and the recommendations of the International Commission on Radiation Protection. The study was carried out at the Isotopes Laboratory (LRI), Department of Nuclear Medicine in Antananarivo, Madagascar. According to the current regulation in radiation protection in Madagascar, the dose limit for the members of the public is limited to 1 mSv. Guidelines for discharge from the hospital are as follows. Patients can travel using public transportation up to 15 minutes. Patients are suggested to sleep apart and restrict contact with partner for 4 days after leaving the hospital. Contact with children should be restricted according to their ages. Time to restrict contact with child ranging from 3 to 10 years is limited to 4 days, and up to 7 days for younger children. This guideline is based on the retained activity of 800 MBq or the external dose rate is less than 40 μSv/h at 1 m. For public transportation, the suggested travel times for thyroid cancer are similar to those recommended by the French group. The length of time for which patients are in contact with children in this study is widely less than recommendations by French Group.

The European X-Ray free electron laser accelerator consists of 808 superconducting cavities grouped in 25 RF stations. The challenges associated with the size and complexity of this accelerator require a high-precision, modular and scalable low level RF (LLRF) system. The Micro TCA technology (MTCA.4) was chosen to support this system and adapted for RF standards. State-of-the-art hardware development in close collaboration with the industry allowed for the system continuity and maintainability. The complete LLRF system design is now in its final phase and the designed hardware was installed and commissioned at FLASH. The MTCA.4 LLRF architecture and system performance results will be shown. Operation strategies and future automation algorithms for performance optimization will also be presented in this paper.

This paper describes a simulation to predict the susceptibility of an advanced avionics control system to electrical transients resulting in logic errors, latched errors, error propagation, and digital upset. The system is based on a custom-designed microprocessor, and it incorporates fault-tolerant techniques. The system being tested and the method of performing the transient-injection experiment are described. Results for 2100 transient injections are analyzed and classified according to charge level, type of error, and location of injection. Logic errors Electrical transient Analog-digital simulation

This paper reports on the development of an interactive, intraoperative dose planning system for seed implant brachytherapy in cancer treatment. This system involves in vivo dosimetry and the ability to determine implanted seed positions. The first stage of this project is the development of a urethral alarm probe to measure the dose along the urethra during a prostate brachytherapy treatment procedure. Ultimately, the system will be used to advise the physicians upon reaching a preset dose rate or dose after total seed decay in the urethra during the seed placement. The second stage is the development of a method and instrumentation for in vivo measurements of the location of implanted seeds in the same frame as for dose planning and the use of these in intraoperative treatment planning. We have developed a silicon mini-detector, miniature front-end, and shaping amplifier with discriminator, connected to the mini-silicon detector at the end of a cable placed in a urological catheter, to satisfy the spectroscopic requirements of the urethral probe. This technique will avoid complications related to overdosing the urethra and the rectum.

The data acquisition system of the CMS experiment at the Large Hadron Collider features a two-stage event builder, which combines data from about 500 sources into full events at an aggregate throughput of 100 GByte/s. To meet the requirements, several architectures and interconnect technologies have been quantitatively evaluated. Both Gigabit Ethernet and Myrinet networks will be employed during the first run. Nearly full bisection throughput can be obtained using a custom software driver for Myrinet based on barrel shifter traffic shaping. This paper discusses the use of Myrinet dual-port network interface cards supporting channel bonding to achieve virtual 5GBit/s links with adaptive routing to alleviate the throughput limitations associated with wormhole routing. Adaptive routing is not expected to be suitable for high-throughput event builder applications in high-energy physics. To corroborate this claim, results from the CMS event builder preseries installation at CERN are presented and the problems of wormhole routing networks are discussed.

The presence of radioactivity, originating from both natural and human-induced sources, is widespread in varying degrees throughout the Earth's crust. Soil, as a fundamental component of the Earth's crust, serves as an ongoing source of exposure to humans. The level of radioactivity in soil is influenced by factors such as soil composition and land usage. It is expected that barren soil exhibits distinct radioactivity levels compared to cultivated soil. To investigate the radioactivity levels within barren soil, a study was conducted on approximately 11 hectares of soil samples located in Niankhene. Utilizing gamma ray spectrometry methodology with a high purity germanium gamma-ray detector, activity concentration levels of radionuclides including 40 K, 137 Cs, 226 Ra, and 232 Th were evaluated. A total of 16 soil samples were collected at depths ranging from 0 to 40 cm with 20 cm intervals. The activity concentrations of the radionuclides were observed as follows: 40 K ranged from below the limit of detection to 34.7 Bq.kg-1 ; 137 Cs varied from 0.06 to 0.80 Bq.kg-1 ; 226 Ra measured was between 7.49 and 101.56 kg-1 ; and 232 Th ranged 0.33 and 12.68 Bq.kg-1. The total dose radiation exposure were 27 nGy/h in this study. Before conducting radiometric measurements, chemical analyses were performed to determine the concentrations of Na, Ca, and Mg, along with measurements of electrical conductivity and pH levels of the soil samples.

The ATLAS combined test beam in the second half of 2004 saw the first deployment of the ATLAS High-Level Trigger (HLT). The next steps are deployment on the pre-series farms in the experimental area during 2005, commissioning and cosmics tests with the full detector in 2006 and collisions in 2007. This paper reviews the experience gained in the test beam, describes the current status and discusses the further enhancements to be made. We address issues related to the dataflow, integration of selection algorithms, testing, software distribution, installation and improvements.

A system test of various components of the Solenoidal Tracker at RHIC (STAR) detector, operating in concert, has recently come on-line. Communication between a major sub-detector, a sector of the Time Projection Chamber (TPC), and the trigger, data acquisition and slow controls systems has been established, enabling data from cosmic ray muons to be collected. First results from an analysis of the TPC data are presented. These include measurements of system noise, electronic parameters such as amplifier gains and pedestal values, and tracking resolution for cosmic ray muons and laser induced ionization tracks. A discussion on the experience gained in integrating the different components for the system test is also given.

We have evaluated the performance of a fine pitch CdTe Double-sided Strip Detector (CdTe-DSD), which was originally developed for the focal plane detector of a hard X-ray telescope to observe the Sun. The detector has a thickness of 750 µm and has 128 strip electrodes with a 60 µm strip pitch orthogonally placed on both sides of the detector and covers an energy range 4 keV to 80 keV. The study of the depth of photon interaction and charge sharing effects are of importance in order to provide good spectroscopic and imaging performance. We study the tail structure observed in the spectra caused by charge trapping and develop a new method to reconstruct the spectra based on induced charge information from both anode and cathode strips. By applying this method, energy resolutions (FWHM) of 0.76 keV and 1.0 keV can be obtained at photon energies of 14 keV and 60 keV, respectively, if the energy difference between the anode and cathode is within 1 keV. Furthermore, the tail component at 60 keV is reduced, and the energy resolution of the 60 keV peak is improved from 2.4 keV to 1.5 keV (FWHM) if the energy difference is greater than 1 keV. In order to study the imaging performance, we constructed a simple imaging system using a 5 mm thick tungsten plate that has a pinhole with a diameter of 100 µm. We utilize a 133 Ba radioisotope of 1 mm in diameter as a target source in combination with a 100 µm slit made from 0.5 mm thickness tungsten. We imaged the 133 Ba source behind the 100 µm slit using a 30 keV peak, with a 100 µm pinhole placed at the center of the source-detector distance. By applying a charge sharing correction between strips, we have succeeded in obtaining a position resolution better than the strip pitch of 60 µm.

We present ground test and space flight data describing a single event anomaly that affects multiple bytes in a stacked DRAM module. A 12 Gbit solid state recorder containing 1,440 DRAM die experiences the anomalous events at a rate requiring testing of a large sample set of these modules. I. BACKGROUND OF ANOMALY A solid state recorder (SSR) containing 12 Gbits of memory for telemetry storage was installed on the Hubble Space Telescope (HST) in February of 1997. The HST is in a 600 km circular orbit at an inclination of 29'. The orbit makes several passes through regions of high energy protons trapped in the South Atlantic Anomaly (SAA) every day. There are also low levels of heavy ions from galactic cosmic rays and solar events (see Figure 1). The maximum linear transfer 1 OE+03 1 OE+02 1 OE+01 '5: 1 OE+OO

We measure the energy dependence of protoninduced LED degradation using large numbers of devices and incremental exposures to gain high confidence in the proton energy dependence and device-to-device variability of damage. We compare single versus double heterojunction AlGaAs technologies (emitting at 880 nm and 830 nm, respectively) to previous experimental and theoretical results. We also present a critical review of the use of nonionizing energy loss in AlGaAs for predictions of on-orbit degradation and assess the uncertainties inherent in this approach.

Spacecraft performance requirements drive the utilization of commercial-off-the-shelf (COTS) components and emerging technologies in systems. The response of these technologies to radiation is often complex. This engenders a set of emerging radiation hardness assurance (RHA) issues which include displacement damage in optocouplers, highprecision and hybrid devices, enhanced low dose rate (ELDR) and proton damage enhancement (PDE) in linear circuits, linear transients, and catastrophic single event effects (SEES) phenomena. NASA has developed an approach to designing reliable space systems which addresses these emerging RHA issues. This programmatic methodology includes hazard definition, hazard evaluation, requirements definition, evaluation of device usage, and application of radiation engineering techniques with the active involvement of designers. Risk assessment is an integral constituent in the approach as is an established program to assess future technology needs for programs.

Bulk samples of Te-doped n-type G a A s w e r e i r r a d i a t e d u s i n g 10 MeV t o 24 MeV protons t o f l u e n c e s between 2 x 10l1 protons/cm2 and 2 x protons/cm2. Majority carrier e l e c t r i c a l e f f e c t s were measured u s i n g t h e van d e r Pauw techn i ues and i t w a s observed t h a t r a d i a t i o n damage w a s minimal a t t h e 10l1 p r o t o n / cm9 fluence.

Polarimetry in astronomy for the hard X-and soft-ray energy range has not been developed much to date. Indeed no dedicated polarimeters have ever been launched either in space or as a balloon-borne experiment. We propose a polarimetry project for hard X-ray and soft gamma-ray astrophysics known as the Coded Imager and Polarimeter for High Energy Radiation (CI-PHER) telescope. The novel design of this telescope, using a matrix of thick CdTe microspectrometers as the detection plane, will allow this type of measurement to be performed for the first time by a dedicated instrument. In order to compare the results already obtained from simulations with experiment, we have constructed a prototype detector of 4 4 pixels, to study the response of this concept of polarimeter to linearly polarized radiation in the 100 keV to 1 MeV energy range. The use of a beamline at the European Synchrotron Radiation Facility (ERSF) allowed us to study double event efficiency and distribution, for beams of nearly 100% linearly polarized radiation in the energy range from 100 keV to 1 MeV. Polarimetric factors higher than 0.4 for relative effiencies higher than 20% were observed. The photon beam energy and detector thickness dependencies will be discussed, comparing these experimental results with those calculated by Monte Carlo simulations.

The main aspects of the design and test (D&T) of a reconfigurable architecture for the Data Acquisition Electronics (DAE) system of the Clear-PEM detector are presented in this paper. The application focuses medical imaging using a compact PEM (Positron Emission Mammography) detector with 12288 channels, targeting high sensitivity and spatial resolution. The DAE system processes data frames that come from a front-end (FE) electronics, identifies the relevant data and transfers it to a PC for image processing. The design is supported in a novel D&T methodology, in which hierarchy, modularity and parallelism are extensively exploited to improve design and testability features. Parameterization has also been used to improve design flexibility. Nominal frequency is 100 MHz. The DAE must respond to a data acquisition rate of 1 million relevant events (coincidences) per second, under a total single photon background rate in the detector of 10 MHz. Trigger and data acquisition logic is implemented in eight 4-million, one 2-million and one 1-million gate FPGAs (Xilinx Virtex II). Functional Built-In Self Test (BIST) and Debug features are incorporated in the design to allow on-board FPGA testing and self-testing during product lifetime.

The design and evaluation of the imaging system Clear-PEM for positron emission mammography, under development by the PEM Consortium within the framework of the Crystal Clear Collaboration at CERN, is presented. The proposed apparatus is based on fast, segmented, high atomic number radiation sensors with depth-of-interaction measurement capabilities, and state-of-the-art data acquisition techniques. The camera consists of two compact and planar detector heads with dimensions 16.5 14.5 cm 2 for breast and axilla imaging. Low-noise integrated electronics provide signal amplification and analog multiplexing based on a new data-driven architecture. The coincidence trigger and data acquisition architecture makes extensive use of pipeline processing structures and multi-event memories for high efficiency up to a data acquisition rate of one million events/s. Experimental validation of the detection techniques, namely the basic properties of the radiation sensors and the ability to measure the depth-of-interaction of the incoming photons, are presented. System performance in terms of detection sensitivity, count-rates and reconstructed image spatial resolution were also evaluated Manuscript

The Clear-PEM detector system is a compact positron emission mammography scanner with about 12000 channels aiming at high sensitivity and good spatial resolution. Front-end, Trigger, and Data Acquisition electronics are crucial components of this system. The on-detector front-end is implemented as a data-driven synchronous system that identifies and selects the analog signals whose energy is above a predefined threshold. The off-detector trigger logic uses digitized front-end data streams to compute pulse amplitudes and timing. Based on this information it generates a coincidence trigger signal that is used to initiate the conditioning and transfer of the relevant data to the data acquisition computer. To minimize dead-time, the data acquisition electronics makes extensive use of pipeline processing structures and derandomizer memories with multievent capacity. The system operates at 100-MHz clock frequency, and is capable of sustaining a data acquisition rate of 1 million events per second with an efficiency above 95%, at a total single photon background rate of 10 MHz. The basic component of the front-end system is a low-noise amplifier-multiplexer chip presently under development. The off-detector system is designed around a dual-bus crate backplane for fast intercommunication between the system boards. The trigger and data acquisition logic is implemented in large FPGAs with 4 million gates. Monte Carlo simulation results evaluating the trigger performance, as well as results of hardware simulations are presented, showing the correctness of the design and the implementation approach.

A compact real-time X-ray and charged particle imager with digitized position output can be built either by coupling a fast scintillator to a photodiode array or by .forming one on a photodiode array directly. Csi(Tl) layers 100-1000 J.UI1 thick were evaporated on glass substrates from a crystal Csi(Tl). When coupled to a crystalline Si or amorphous silicon (a-Si:H) photodiode and exposed to calibrated X-ray pulses, their light yields and speed were found to be comparable to those of a crystal Csi(Tl). Single 13 particle detection• was demonstrated with this combination. The light spread inside ev~porated Csi(Tl) was suppressed by its columnar structure. Scintillation detection gives much larger signals than direct Xray detection due to the increased energy deposition in the detector material. Fabrication of monolithic type X-ray sensors consisting of Csi + a-Si:H photodiodes is discussed.

This paper reports about state-of-the-art artificial Single Crystal Diamond (SCD) neutron detectors based on a multilayered structure and grown by chemical vapour deposition (CVD) technique. Multilayered SCD detectors covered with a thin layer of 6 LiF allow the simultaneous detection of both slow and fast neutrons and can operate in pulse and current mode. These detectors can also be produced with a thin layer of Boron. Application of SCD detectors to neutron detection around fusion tokamak is reported. Some problems related to the processing of the very fast electrical pulse produced by diamond are addressed and the achieved and foreseen development of the processing electronics is reported as well.

a new and fully engineered version of the YAP-(S)PET small animal scanner has been recently installed. The new YAP-(S)PET is able to perform both PET and SPECT studies on small animals. The scanner is made up of four heads: each one is composed of a 4 4 cm 2 YAlO 3 :Ce (or YAP:Ce) matrix of 20 20 elements, 2 2 25 mm 3 each, coupled to a Position Sensitive Photomultiplier (PS-PMT) (Hamamatsu R2486). The four modules are positioned on a rotating gantry. The switching to the SPECT modality is easily made by mounting a high resolution parallel hole (0.6 mm , 0.15 mm septum) lead collimator in front of each crystal. This paper reports the performance of the system in terms of absolute sensitivity and spatial resolution for both PET and SPECT modalities. The scatter fraction and noise-equivalent count rate (NEC) for a mouse phantom for different energy windows have been measured in PET modality. Images of phantoms and animals are also presented.