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Passive Neutron Coincidence Counting (PNCC) and Passive Neutron Multiplicity Counting (PNMC) techniques are important non destructive assay methods used in the quantification of plutonium and other spontaneously fissile materials across the fuel cycle. They are based on Multiplicity Shift Register (MSR) pulse train correlation analyzers such as the Canberra Multiplicity Shift Register (MSR) JSR-14. The JSR-14, although quite successful, is somewhat limited by a 4 MHz SR and has no front panel display. Los Alamos National Laboratory (LANL) has recently developed a hand-held multiplicity register (HHMR) that possesses a 50 MHz SR as well as an interactive front panel display with user settable parameters. Under CRADA (cooperative research and development agreement) guidelines, Canberra Industries will commercialize the product. The display and user interface allows for parameter entry and provides the user with feedback of the current operating parameters as well as the MSR results, e.g., multiplicity histograms. The higher MSR clock speed will provide functionality not previously possible under extreme counting conditions, e.g., waste assay with relatively high-gram quantities of heat source material. A prototype HHMR unit was obtained from LANL and has been tested. In this paper, we present the test results of the reliability of the unit, the user interface functionality, support for existing software, and the performance of the 50 MHz MSR. The reliability tests involved the integrity of the battery and voltage supplies, signal triggering performance, and the robustness of the PC USB/virtual COM port interface. The software compatibility tests were conducted using the latest available versions of the LANL INCC and Canberra NDA 2000 software packages. A 20 MHz de-randomizer board was installed into a Canberra neutron coincidence counter to examine the performance of the 50 MHz JSR-15 MSR as compared to the 4 MHz JSR-14 MSR The functionality of JSR-14 and HHMR at low instantaneous counting rates as well as high rates was tested using a random pulser, Am-Be and 252Cf sources. In this paper we report on the results for the tests conducted during the evaluation period.

Signal splitting strategy is one of the methods to get implement circuit that gets real-time trigger timing information in addition to post trigger amplitude information in current muon tracker detector. Although signal splitting strategy is cost effective and need short development time, there can be degradation in SNR and jitter and it is needed to analyze the signal splitting effect on the original amplitude signal path and newly added timing signal path to ensure both signal paths requirements are met. This paper analyzes the relations between the signal splitting elements, the coupling capacitors, and the two signal paths requirements. The requirements are signal to noise ratio parameter for the amplitude signal path and jitter parameter for the timing signal path. The results and approach of this paper can be applied to other signal splitting applications to check the feasibility and to set correct splitting ratio which meets the multiple requirements of the application.

An analysis of publications related to high energy physics computing in refereed journals is presented. The distribution of papers associated to various fields of computing relevant to high energy physics is critically analyzed. The relative publication rate of software papers is evaluated in comparison to other closely related physics disciplines, such as nuclear physics, radiation protection and medical physics, and to hardware publications. The results hint to the fact that, in spite of the significant effort invested in high energy physics computing and its fundamental role in the experiments, this research area is underrepresented in scientific literature; nevertheless the analysis of citations highlights the significant impact of software publications in experimental research.

In the past years, precise measurements of time intervals have been realized using methods such as time- stretching, Vernier and delay line. In this paper, we present two high-resolution time-interval measuring system implemented in a SRAM-based FPGA device. The two methods ought to be used for time interpolation within the system clock cycle. In the first method, dedicated carry lines are used to perform fine time measurement, while in the second one a differential tapped delay line is used. In this paper we compare the two architectures and show their performance in terms of stability and resolution.

Optical and electrical crosstalk are the parameters of photodetector arrays for medical imaging applications that often require special attention of the system developers and researchers. This paper studies optical and electrical crosstalk for the back-illuminated, thin pin photodiode arrays built on 75- mum and 100- mum thickness single silicon dies. The features of the arrays include high quantum efficiency, fast signal rise time, very small AC and DC electrical crosstalk (~ 0.01%) within the spectral range 400 to 800 nm. The paper compares the noise performance and detectivity of back-illuminated photodiode arrays with isolating diffusion between pixels and conventional arrays with no isolation between pixels. Different sources of optical crosstalk in scintillator-based X-ray imaging applications are discussed for two types of arrays. The noise characteristics and detectivity for the detector arrays with optical and electrical crosstalk were estimated to be 3-5 times better for the arrays with isolating diffusion than for the conventional photodiode arrays. A brief comparison with the front-illuminated arrays is also provided.

This paper reports on the initial performance evaluation of a small field-of-view, mobile PET/SPECT system for bedside imaging. The system was designed to move within a hospital to image patients who cannot easily be transported to a conventional PET or SPECT facility, for example, patients within an intensive care unit (ICU). The focus of the system is cardiac imaging in which both viability (18F fluorodeoxyglucose; FDG) and perfusion (99mTc Sestamibi) images are desired. This paper evaluates the capabilities of the mobile system for acquisitions at both 140 keV (Tc-99 m) and at 511 keV (F-18) operated in single photon counting mode. Parameters evaluated were the planar and reconstructed SPECT spatial resolution, the intrinsic energy resolution, sensitivity, and the count rate capability. Results demonstrate an intrinsic energy resolution of 32% at 140 keV and 23% at 511 keV, a planar intrinsic spatial resolution of 0.56 cm full width half-maximum (FWHM) at 140 keV and 0.61 cm FWHM at 511 keV, a system spatial resolution at 10 cm of 1.14 cm FWHM for both 140 keV and 511 keV, a reconstructed SPECT spatial resolution of 1.37 cm at 140 keV (22 cm radius-of-rotation), a sensitivity of 3.1 countsldrmuC-1ldrs-1 at 140 keV and 0.48 countsldrmuC-1ldrs-1 at 511 keV, and a maximum count rate of 1.46 times 105 counts/s at 140 keV and 1.56 times 105 counts/s at 511 keV.

Biomedical image registration or geometrical alignment of 2-D/2-D image data is increasingly important in diagnosis, treatment planning, computer-guided therapies and in biomedical research. In this paper we present affine registration of same modality images and different (MR & CT) modality images. Automatic registration is achieved by maximization of a similarity metric, which is mutual information (MI) or relative entropy, based on the concept of information theory. Registration based on MI usually requires an optimization technique to achieve correctly aligned images. There exist many optimization schemes, most of which are local and require a starting point. Unfortunately the functions of similarity metric used in the present problem are nonconvex and irregular and therefore global methods are often required. In this paper, we have implemented genetic algorithm as an optimization technique to overcome these problems. Experimental results show our algorithm is a robust and efficient method.

We have reported a fast iterative algorithm, DRAMA (Dynamic RAMLA), for emission CT. The relaxation parameter is controlled in such a way that the contribution of noise from subsets to the image is balanced at the end of each main-iteration. DRAMA provides a rapid convergence with a good S/N ratio by avoiding the limit-cycle problem. In this paper, we present "TOF-DRAMA" developed for time-of-flight (TOF) PET with the same strategy. We first formulated the recursive formula of TOF-DRAMA. Next, we developed a simple method to calculate the relaxation parameter taking into account of the TOF resolution. In TOF-DRAMA, we generate a rotated image, /j-matrix, in the TOF direction. The /j-matrix is converted to "t- matrix" by taking convolution with the TOF response function, and the ratio of ^-matrix to the measured TOF projection is used for the iterative updating of the image. The sizes of h- and t- matrixes were determined by making a compromise between the imaging performance and the computation time. This paper describes the results of the simulation studies on the convergence behavior, spatial resolution, statistical noise, structural error, etc. In conclusion, TOF-DRAMA is useful as a fast statistical reconstruction algorithm for TOF-PET. The use of the TOF information improves not only the S/N but also the converging speed of the algorithm. The TOF gain in the S/N ratio was fairly close to the theoretical value.

This paper discusses the design and imaging capabilities of xCAT, a mobile CT scanner aimed specifically at assisting surgical procedures of head and neck and for use in intensive care units. A high degree of compactness and portability has been achieved by utilizing large area flat-panel detectors, cone-beam imaging geometry and by careful mechanical and electrical design of the scanner. The system is powered up from standard electrical wall outlet, but can also be operated from a battery backup power source if needed. Furthermore, the scanner uses a flat-panel receptor capable of acquisition in the so called dual-gain mode [1], which significantly extends the effective dynamic range of the detector. As a result, improvements in the soft-tissue imaging capabilities over most of the currently available flat-panel detector cone-beam CT scanners have been achieved. This paper will discuss the design, data processing chain, patient's dose and image quality metrics for this system. The first soft- tissue brain images of a living human subject obtained with this unit will also be presented.

In this paper, we presented a framework for calculation of a projection operator for emission tomographic reconstruction, using content-adaptive mesh model (CAMM) for image representation, which can incorporate major image degradation models, namely attenuation and parallel hole collimator response. The CAMM is an efficient image description based on non-uniform sampling and linear interpolation. The data acquisition process, e.g. forward projection, is calculated using a ray-casting algorithm. We tested, successfully, the proposed projection operator model using a simulation and a maximum-likelihood expectation maximization reconstruction algorithm. The research described in this paper establishes a methodology for future development of 4D (deformable) CAMM reconstruction.

The advantage of LaBr3(Ce3+) over NaI(TI) scintillators with respect to gamma spectroscopy and radioisotope identification has been discussed in many papers. However, implementing such detectors in field instruments for routine use in homeland security applications differs from demonstrating their capabilities in a laboratory. This paper reviews several issues solved in the development phase of a commercial hand-held radio-isotope identification device (RIID), the identiFINDERreg ultra L. Aspects as the detector stabilization, selection and optimization of an appropriate photomultiplier tube, as well as calibration, spectrum linearization, and quality assurance procedures in the production process are addressed.

Reconstructions in emission tomography at 511 keV have to address insufficient amount of data due to poor performances of detectors at such energy. SPECT with classic collimators is generally not adapted to acquire such images, unless a large open-fraction collimator is considered. In this paper we propose a novel configuration for direct 3D-reconstruction from a single 2D-planar non-parallel projection, that is a challenging and ill-posed problem. First, a coded aperture and a 2D-detector are simulated to define a model of the imaging system and to generate synthetic data. In order to address the absence of sufficient data support, 3D-objects that are synthesized stand in the near- field region, at just a few centimetres from the surface of the detector. This configuration maximises the geometrical efficiency and consequently enhances the amount of data contained in the unique observed image. Secondly, an accelerated ML-EM algorithm is used to reconstruct 3D-objects. The basis of our approach reflects the assumption that the inner-structure of the transition matrix used for modelling the system affects significantly the behaviour of ML-EM algorithm and the whole reconstructed spatial distribution. The transition matrix depends directly on the geometry of the collimator. The impact of this geometry on the structure of the transition matrix is studied. This paper shows that a small-size detector is able to perform a 3D-reconstruction of a small object standing in the near-field domain, from a single 2D-image. Reconstructed objects exhibit a good spatial resolution : two 5 mm-diameter cylinders with a centre-to-centre distance of 6 mm are clearly separated. Cylindrical shapes are well-preserved, although depth direction is deformed. Promising simulations demonstrate the extreme potentials of our approach.

In this paper, the new architecture of a high-speed continuous time digitizer is proposed. With the aid of a two-level multiphase sampling technique, the time digitizer can use only 16 delay cells and DFFs to perform the flash-type conversion of 64-stage interpolation. The time digitizer can obtain 78 ps resolution with a reference frequency running at 200 MHz. The continuous input clock frequency can be up to 250 MHz. The test chip is fabricated in TSMC 0.18 mum 1P6M mixed mode process. The layout area occupies 1.08 mm2. The DNL is within -0.62 ~ +0.51 and INL within -0.99 ~ +0.98. A novel clock multiplier is also introduced to provide multiphase generation with the frequency output range within 0.64 ~ 1.8 GHz.

We describe the design and report on the experimental results of a novel thermal and cold neutron imaging detector utilizing neutron sensitive (10B-doped) microchannel plates (MCPs). In this detector, the incoming neutron interaction products produce secondary electrons at the pores adjacent to the absorption point within the MCP glass. This electron signal is then multiplied by a stack of conventional MCPs within those adjacent pores limiting the spread of the signal to less than two pore diameters (currently 6-10 mum pores on 8-12 mum centers). The event position then can be encoded by a number of readout techniques already developed for photon/charged particle counting applications. This paper presents the results of experimental evaluation of neutron sensing MCP detector with Medipix2 readout allowing operation at high counting rate mode (>100 MHz level) at a spatial resolution limited by the 55 mum pixel size of the Medipix2 readout. Other attractive features of MCP neutron detectors are their high detection efficiency (approaching 50% levels) for thermal and cold neutrons and the absence of readout noise.

The temperature monitoring system for BES-III experiment is described. The paper covers characteristic of this system. The temperature and humidity sensors are commercial products with digital outputs. Two types of custom design readout modules, which have standard 485 outputs, are designed to interface with detection sensors. The readout modules are communicated with control computer using USB-485 converters. The system is very flexible and cost-effective.

Super-Kamiokande is a ring imaging water Cherenkov detector for astro-particle physics that consists of 50 kton pure water and about 13000 photomultiplier tubes (PMTs). We are planning to upgrade all the front-end electronics in next year. By high speed signal processing electronics, we will record all the hits of all the PMTs without any hardware filtering, aiming observations of much fainter signals of the supernova relic neutrinos, lower energy (~ 3 MeV) solar neutrinos, neutrino burst from nearby galactic supernova, and so on. The energy resolutions of multi-GeV atmospheric neutrino events will also be improved by the electronics. The new front-end electronics is based on charge to time converters (QTCs) and multi-hit TDCs. TCP/IP based readout channel is implemented to handle large amounts of data. We have developed a custom ASIC QTC and evaluated the characteristics of the chip and the prototypical board; high-speed (1 MHz cycle), high sensitivity for single photo- electron signal, good charge (0.1 pC RMS) and timing (0.3 ns RMS) responses, and wide charge dynamic range (2500 pC). In this paper, the design and the performance of the front-end board are described.

This paper presents the architecture and the status of the optical multiplexer board (OMB) for the ATLAS/LHC tile hadronic calorimeter (TileCal). This board will analyze the front-end data CRC to prevent bit and burst errors produced by radiation. Besides, due to its position within the data acquisition chain it will be used to emulate front-end data for tests. The first two prototypes of the final OMB 9U version have been produced at CERN. Detailed design issues and manufacturing features of these prototypes are described. These prototypes are being validated while firmware developments are being implemented in the programmable devices of the board.

We are currently developing a handheld radioisotope identifier containing eighteen position-sensitive CdZnTe crystals. In addition to isotope identification, the device performs basic Compton imaging to determine the location of suspected sources. This paper gives an overview of the electronics system we have designed for this instrument. We use specialized application-specific integrated circuits to preprocess the outputs of each CdZnTe crystal. A low-power microprocessor running Windows CE drives the user interface and implements the isotope identification and directionality computations. Finally, we use a field-programmable gate array to perform the computationally intensive imaging tasks in real time.

The paper presents a mixed analog-digital configurable instrument for processing signals from different type of scintillation detectors. We discuss design, realization and firmware structure of the system. We mainly present preliminary result obtained with the use LaBr3 detectors. The main feature of the architecture is the adaptability to a wide range of different operative conditions by changing configuration both of the digital and of the analog section. Using modular hardware and firmware architecture and digital configurable devices (a digital signal processor -DSP and a field programmable gate array - FPGA) it's possible to achieve optimum performance in an extremely wide range of application.

A new type of 2-dimensional curved position- sensitive neutron detector is developed for ammplication at single crystal diffractometer, which covers 70deg in horizontal and 45deg in vertical direction. The prototype development of this curved detector is aimed at testing of technical feasibility of detector parameters such as internal structure, new method to build-up anode and cathode planes' build-up, technical difficulties in assembly procedure, optimization of design parameters in terms of mechanical and electric properties, etc. In this paper, we present the preliminary results of the curved detector.

AMS-02 is a space experiment that will perform cosmic ray observations on board of the International Space Station starting from July 2009. This presentation describes the control electronics for the silicon tracker cooling system in the AMS-02 apparatus. It also contains a brief description of the tracker detector and its cooling system necessary for the description of the electronics. The tracker cooling system includes a set of various sensors and actuators which are necessary for bringing the tracker detector to a uniform temperature at which it can operate correctly. The sensors include: Pt1000 thermistors, semiconductor thermal sensors, differential and absolute pressure sensors, and pump rotational speed sensors. The actuators are: resistive heaters, peltier heat pumps, and liquid pumps. The electronics process the sensor signals, control the actuators, and perform automatic safeguard actions so that the system is capable of operating in a stand-alone mode, i.e. without operator intervention. The electronic system also sends relevant operational data to ground. This paper will describe the design, construction and space qualification of these control electronics.

We describe the design optimization process and performance characterization of a next generation neutron telescope, with imaging and energy measurement capabilities, sensitive to neutrons in the 1-20 MeV energy range. The response of the fast neutron imaging telescope (FNIT), its efficiency in neutron detection, energy resolution and imaging capabilities were characterized through a combination of lab tests and Monte Carlo simulations. Monte Carlo simulations, together with experimental data, are also being used in the development and testing of the image reconstruction algorithm. FNIT was initially conceived to study solar neutrons as a candidate instrument for the inner heliosphere sentinel (IHS) spacecraft. However, the design of this detector was eventually adapted to locate special nuclear material (SNM) sources for homeland security purposes, by detecting fission neutrons. In either case, the detection principle is based on multiple elastic neutron-proton scatterings in organic scintillator. By reconstructing event locations and measuring the recoil proton energies, the direction and energy spectrum of the primary neutron flux can be determined and neutron sources identified. This paper presents the most recent results arising from our efforts and outlines the performance of the FNIT detector.

The instrumentation group at the Monash Centre for Synchrotron Science have developed a low cost generic data acquisition system. This system is to be used in a variety of applications and to assist in the design and testing of emerging detectors. The system utilises a desktop PC which interfaces to a detector via one or more custom 64-bit PCI cards, each equipped with an Altera CycloneIItrade FPGA (2c70 ) and plug-in daughter boards, this provides flexibility to easily customise analogue and digital signal processing. A GUI application controls the system via variables and scripts, renders and analyses real-time data, and supports importing and exporting in a variety of formats. This paper presents an overview of the data acquisition system and the process of interfacing with a two-dimension multi-wire proportional chamber with delay-line readout with an expected timing resolution of 10 ps.

A high resolution electromagnetic calorimeter has been proposed as one of the major detector components of the future PANDA detector at FAIR The homogeneous calorimeter is based on high quality PWO-II scintillator crystals operated at a temperature of T=-25degC and readout via large area avalanche photo diodes. The paper summarizes the status of the detector performance, radiation hardness and the present layout of the whole target calorimeter.

High trigger rate nuclear physics experiments proposed for the 12 GeV upgrade at the Thomas Jefferson National Accelerator Facility create a need for new high speed digital systems for energy summing. Signals from electronic detectors will be captured with the Jefferson Lab FADC module, which collects and processes data from 16 charged particle sensors with 10 or 12 bit resolution at 250 MHz sample rate. Up to sixteen FADC modules transfer energy information to a central energy summing module for each readout crate. The sums from the crates are combined to form a global energy sum that is used to trigger data readout for all modules. The Energy Sum module and FADC modules have been designed using the VITA-41 VME64 switched serial (VXS) standard. The VITA- 41 standard defines payload and switch slot module functions, and offers an elegant engineered solution for Multi-Gigabit serial transmission on a standard VITA-41 backplane. The Jefferson Lab Energy Sum module receives data serially at a rate of up to 6 Giga-bits per second from the FADC modules. Both FADC and Energy Sum modules have been designed and assembled and this paper describes the integrated tests using both high speed modules in unison.

AMS-02 is a space experiment that will perform cosmic ray studies on board of the international space station starting from July 2009. This paper describes the design and production of electronic ground support equipment (EGSE) that emulates the silicon tracker cooling system in the AMS-02 apparatus. This emulator is needed in order to test the control electronics of the cooling system without the cooling system itself. The cooling system will be assembled and integrated separately and with a different schedule. Using the EGSE, with a proper emulation software, it will also be possible to simulate the behavior of the cooling system in space. The tracker cooling system includes a set of different sensors and actuators which are necessary for bringing the tracker detector to a uniform temperature at which it can operate properly. The sensors include: Pt1000 thermistors, semiconductor thermal sensors, differential and absolute pressure sensors, and pump rotational speed sensors. The actuators are: resistive heaters, Peltier heat pumps and liquid pumps. The EGSE should simulate the behavior of all these sensors and actuators. This means that it must generate the same signals from the electrical point of view but also its global behavior, namely the response to any internal and external condition change should be the same as the actual tracker cooling system. In order to achieve this performance appropriate software that includes the simulated response of the tracker cooling system will be developed. The EGSE has been developed in three phases: in phase 1 we emulated the electrical behavior of each sensor or actuator as a single unit, in phase 2 we integrated those sensors in a single unit and we added a USB computer interface and basic control software. In phase 3 we will develop software emulating the behaviour of the entire tracker cooling system.

The US Department of Energy's transuranic (TRU) waste inventory includes about 4,500 m3 of remote-handled TRU (RH-TRU) wastes composed of a variety of containerized waste forms having a contact surface dose rate that exceeds 2 mSv/hr (200 mrem/hr) containing waste materials with a total TRU concentration greater than 3700 Bq/g (100 nCi/g). As part of a research project to investigate the use of active Compton-suppressed room-temperature gamma-ray detectors for direct non-destructive quantification of the TRU content of these RH-TRU wastes, we have designed and purchased a unique detector system using a LaBr3(Ce) primary detector and a Nal(Tl) suppression mantle. The LaBr3(Ce) primary detector is a cylindrical unit ~25 mm in diameter by 76 mm long viewed by a 38 mm diameter photomultiplier. The Nal(Tl) suppression mantle (secondary detector) is 175 mm by 175 mm with a center well that accommodates the primary detector. An important feature of this arrangement is the lack of any "can" between the primary and secondary detectors. These primary and secondary detectors are optically isolated by a thin layer (.003") of aluminized Kapton. This arrangement virtually eliminates the "dead" material between the primary and secondary detectors, a feature that preliminary modeling indicated would substantially improve the Compton suppression capability of this device. This paper presents both the expected performance of this unit determined from modeling with MCNPX, and the performance measured in our laboratory with radioactive sources.

This paper describes the design of time-to- digital converter ( TDC ) with two level Vernier delay line (VDL) , which is used to solve the problem of long conversion time in single level VDL and reduce the number of elements. The time interval to be measured between two pulse signals is separated into integral period part and non-integral period part by control circuit. Integral part is sent to counter, and non-integral parts are sent to the two level VDL. In the first VDL can get coarse resolution ( Tclk/N ) , and the signals will be transmitted to the second VDL by the proposed interface circuit. Fine resolution (Tclk/N2) can be gotten in the second VDL. Finally, readout circuit converts thermal code to binary code and do the subtraction to obtain the final results. The bias voltage of delay elements in VDL is controlled by DLL, this makes delay elements can stably provide two kinds of delay time for VDL. The circuit is realized with the process of TSMC CMOS 0.18 um 1P6M. 200 Mhz clock frequency is chosen in the circuit. From the simulation results, the conversion time is smaller than 5 clock periods, the maximum time can be measured is 75 ns. After the fine resolution is modified to 29.6 ps, the DNL is within -0.33LSB - +0.69LSB , and INLis within +0.47LSB - +1.08LSB.

In this paper, the impact of random arrival time on the amplitude resolution is analyzed for digital spectrometers. The improvement performance of amplitude estimation is also analyzed by using timing techniques. This effect relies on the sampling frequency fs and the characteristics of analog section and digital filters. The equivalent noise charge ENCa and baseline VBL caused by this effect is derived for digital filters. For the digital trapezoidal filter using a charge sensitive preamplifier and a simple CR-RC circuit as analog section, the minimum fs is required to be 7/tau to make ENCa / Qin lower than 10-3, i.e. ENCa is only 6.25 electrons with 1 fC detector charge. The Cramer-Rao Limited Bounds (CRLB) for estimating arrival time and amplitude synchronously is also calculated. This work will provide a selection criterion for choosing fs, analog prefilter and timing method to reduce the influence of random arrival time.

A new detector system having two layers of three by three 3-D position sensitive CdZnTe gamma-ray spectrometers is being developed. Each detector module consists of a 1.5times1.5times1.0 cm3 pixellated (11times11 pixels) CdZnTe detector and a VAS_UM2.3/TAT4 ASIC front-end board. Using the 3-D position sensing technique, each detector can be electronically divided into 11times11times40 (40 depth slices) small voxels. The detector response within each voxel is reasonably uniform (variations in weighting potential and electron trapping are minimized) and the energy resolution can be very good (~1% FWHM at 662 keV). A calibration matrix can be derived based on the voxel response so that the performance of entire detector can be very close to the performance of small voxels. However, each voxel needs a reasonable amount of events for the calibration, thus the number of calibration events needed for the whole detector is considerably large - ~50 million for each detector. This requirement poses a challenge to the calibration of the system especially for large arrays. Simply reducing the readout dead time for each event may not be the ultimate solution due to other bottlenecks in the system such as data transfer rate and data processing speed. This paper will analyze the bottlenecks in the current dual-array system and discuss possible strategies to speed up the calibration process.

The TPC read out by GEM detector has many advantages over the traditional ones read out by MWPC (Multi- Wire Proportional Counter). It is a very promising candidate for the central tracking system of International Linear Collider (ILC). In our lab, a GEM-TPC prototype was designed and constructed successfully; the performance of the prototype has been studied; some of the test result using cosmic-ray is presented in this paper.

A new design for a compact and rugged high- pressure xenon-fill ionization detector is being explored at Constellation Technology Corporation (Constellation). The basic design approach is to use a detector geometry that eliminates the effect of the induced charge from uncollected ions without using any shielding mesh. This approach is called a virtual grid ionization chamber and can be employed in a variety of different configurations. We have built several prototypes of slightly different design, and some have yielded a FWHM resolution of 2% at 662 keV. These prototypes, being small, are best suited for use in hand held nuclear identifiers and Unmanned Aerial Vehicles (UAVs). However, this technology easily lends itself to being scaled up to large meter-sized panels that will provide high resolution, large area, and position sensitivity on a scale of 1 cm or better. This paper discusses Constellation's current status of this virtual Frisch grid technology and plans for the future.

In the framework of an on-going R&D program on CZT detectors for astrophysical applications, we have started a study to address peculiar problems affecting this kind of detectors (e.g. response dependent on the interaction depth and multiple hit events) using a digital approach: the output of an analog front end chain based on a fast charge preamplifier, which preserves the shape of the signal as generated by the detector, sampled with a fast ADC, is processed to extract information to improve the performance, in particular the energy resolution. In this context, we have developed a flexible readout electronics to be used to characterize CZT array and test digital processing algorithms. The system includes analog front-end electronics, digital signal processing based on an FPGA board, and a Gb Ethernet interface for PC-based data acquisition. Current scheme allows the readout of a 4x4 pixels, which allows us to test the algorithms even for multi-pixels events and checking cross-talk effects. However, the system has been designed to be easily extended to an higher number of pixels by duplicating the Analog Front End board. Up to 4 AFEE boards can be managed by the system (thus supporting 64 channels, allowing a 16x16 array to be readout). Performance of the system with a commercial 4x4 pixels CZT (eV-products) will be reported in the paper.

The ATLAS experiment is getting ready to observe collisions between protons at a centre of mass energy of 14 TeV. These will be the highest energy collisions in a controlled environment to-date, to be provided by the Large Hadron Collider at CERN by mid 2008. The ATLAS Trigger and Data Acquisition (TDAQ) system selects events online in a three level trigger system in order to keep those events promising to unveil new physics at a budgeted rate of ~200 Hz for an event size of ~1.5 MB. This corresponds to a reduction of O(10^5) from the initial bunch-crossing rate of 40 MHz at nominal operating conditions. This paper focuses on the data-logging system on the TDAQ side, the so-called "Sub-Farm Output" (SFO) system. It takes data from the Event Filter farm, which is the third level trigger, and it streams and indexes the events into different files, according to each event's trigger path. The data files are moved to CASTOR, the central mass storage facility at CERN. The final TDAQ data-logging system has been installed using 6 Linux PCs, holding 24 disks of 500 GB each, managed by three RAID controllers on each PC. The data-writing is managed in a controlled round-robin way among three independent filesystems associated to a distinct set of disks, managed by a distinct RAID controller. This design allows fast I/O, which together with a high speed network permits to minimize the number of SFO nodes. We report here on the functionality and performance requirements on the system, our experience with commissioning it and on the performance achieved.

The PSPMT readout systems that are generally found in technical literature are usually based on two different principles: those with single channel acquisition and those in which the channels are connected together by a resistive chain. In this paper we present a single channel acquisition readout electronics based on easily available commercial ICs. The aim of this study is to acquire valuable information for the development of an application specific integrated circuit (ASIC). The setup is a matrix of 4 Hamamatsu H8500 PSPMTs, assembled with a 10cm x 10cm LaBr3:Ce crystal. Due to the high number of channels (256) and to the connector layout, 16 different PCBs with one standalone CPU each were used in order to calculate, with a parallel algorithm, the collected charge center of gravity and to download data to a PC. The system is capable of 250 KSample/sec, a rate that is well beyond the common rates found in these kind of applications and allows to avoid dead times between the acquisition of a meaningful event and the next.

We have developed a detection module based on a Silicon Drift Detector to assess the feasibility of medium light elements (down to Z=11 - Na) detection in PIXE measurements at on of the beam-lines with external proton beam at the Tandetron in LABEC (INFN, Firenze, Italy). The achieved energy resolution is of the order of 134 eV FWHM at Mn - Kalpha line for count rates of about 100 Hz with the detector cooled at -30degC. The requirement of medium-light elements detection together with the low beam current limit imposed by the analysis of cultural heritage objects impose to shorten as much as possible the sample-detector distance thus increasing the rate of back scattered protons. In order to limit the rate of back-scattered protons we have coupled a polycapillary lens to the detector. In this paper we will discuss the detection module characteristics and concentrate on the measurements carried out at LABEC to assess the detection module performance in true experimental conditions.

Light monitoring will play a crucial role in maintaining the energy resolution of the CMS lead tungstate crystal electromagnetic calorimeter (ECAL) in situ at LHC. Since 2001, a laser based monitoring system has been used in the CMS ECAL beam tests at CERN. While the stability of the laser pulse energy and width, measured in 24 hours, is at a level of 3%, a long term degradation of both the laser pulse energy and the width were observed, as well as a drift of the laser pulse center timing at 2 ns/day. This degradation and drift, caused by the natural aging of the DC Kr lamp, would affect respectively the monitoring precision and the synchronization between the laser pulse and the ECAL ADC clock. This paper presents a design and implementation of a software feedback control which stabilizes the laser pulse energy, width and timing. With the software feedback implemented, a stability of the laser pulse energy and width at 3% level and a pulse timing jitter at 2 ns were observed in laser runs lasted for more than 3 months. The 0.5% energy resolution of the CMS PbWO4 crystal ECAL is maintained after applying the laser monitoring corrections in a beam irradiation test.

This paper describes the data acquisition system (DAQ) developed for the PISASSO project (Project In Canada to Search for Supersymmetric Objects) - the ongoing low background experiment located about 2 km underground at the SNOLAB, Ontario, Canada. This experiment employs an unconventional radiation detecting technique using piezo sensors to detect production of sound by superheated liquid when nuclear recoil takes place in the active region of the detector. Related to such technique specifics of the electronics requirements are discussed in details. The evolution of the DAQ solutions is presented for three different stages of the experiment corresponding to increased active mass of the detector during each stage. Emphasis is given to the current version of DAQ designed for a total of 32 detectors (288 channels). A brief description of the future scaling to 4000 channel system is given as well.

The International Linear Accelerator (ILC) is the currently proposed electron-positron linear collider to complement the proton-proton Large Hadron Collider (LHC) located at CERN. One of the main problems foreseen for the ILC detectors is the need for a low material budged on the interaction region. Also, due to its foreseen high density electronics on the tracker, a more efficient way of powering the system is required. In this paper we describe a first step for the development of a power system that can fulfill the ILC calls for low mass and low power. Initially a basic mathematic model of the problem is introduced followed by the description of a proposed system test concept.

In this paper a low-noise preamplifier for liquid- xenon ionization detectors is presented. The preamplifier has a cold front-end to be operated in liquid xenon at ~160 K and a warm part installed 15-cm apart and working at room temperature. It features an unusually high sensitivity of ~70 mV/fC. This specification is required because the net charge delivered in liquid xenon per unit energy is one order of magnitude lower than in silicon or germanium detectors. The preamplifier consists of a JFET-input charge-sensing stage with a feedback capacitance as low as 0.2 pF and a low-noise gain stage with differential output stage, able to drive 50Omega terminated cables. With a detector capacitance of 33 pF the preamplifier features an Equivalent Noise Charge of ~110 electrons r.m.s. at a shaping time of 6 mus, and a risetime of ~75 ns.

On-going work suggests that a RPC-based small animal pet camera can be built with a FWHM resolution below 0.5 mm and at a very competitive cost. The camera being developed demands a high-resolution data acquisition system along with very good trigger coincidence detection and on-line data reduction. In this paper the actual system specifications are given and a solution is discussed. The elected solution includes the development of four similar data acquisition modules, each with 16 channels based on 12-bit, 70 MSPS ADCs with LVDS outputs, dedicated memory, trigger logic, processing unit, and a USB 2.0 interface. The trigger and data processing logic of each module were placed inside a Xilinx-4 Virtex FGPA. The proposed solution allows a cheap and efficient system to be constructed in a PC-centric way.

The Louisiana High Altitude Student Payload (HASP) program is designed to carry twelve student payloads to an altitude of about 36 km with flight durations of more than sixteen hours. Payloads are designed and built by college and university students and are used to test compact satellites and to fly other related space science experiments. The major goals of HASP are to foster student excitement in an aerospace career path and to help address workforce development issues in Louisiana. HASP plans to provide a "space test platform" to encourage student research and stimulate the development of student satellite payloads and other space-engineering products. In 2006, physics students from the University of Louisiana at Lafayette built a low mass cosmic ray detector using aluminum absorbers and standard x-ray film (with image intensifiers). This 10 kg payload flew from the Columbia Scientific Balloon Facility in Fort Sumner, New Mexico in early September 2006 and was a great success. The students are currently analyzing data from a second 10 kg nuclear stack detector that was flown in September 2007. The purpose of this paper is to present results from the 2006 and 2007 flights of our low mass cosmic ray detector. Emphasis will be placed on the "hands-on" and step-by-step approach used to provide students with practical space-related skills developed as part of the HASP program.

Reliability of electronic components is defined in terms of mean time between failures (MTBF). Temperature variations and operating conditions have a substantial effect on the MTBF of individual components as well as overall performance of the system. To fundamentally improve reliability, the design should be focused on improving the robustness of the basic functions of circuit or process and apply parameter design methods to optimize the basic functions approach under real conditions. These robust design activities should be conducted by taking into consideration the physics of individual components, operating conditions, circuit board layout, and power requirements. Because of the evolution of the reliability of electronic circuits toward very low failure rate, the statistical analyses through accelerated ageing experiments become too expensive. Today, a deterministic approach of the physics of failure is necessary to estimate the life duration of the circuits. As the ageing mechanisms are highly dependent on the circuit operating conditions, electrical simulation is a very useful tool to help the assessment of the degradation effect. Cooling methods such as sidewall cooling of chassis is described in MIL-STANDARDS. However, temperatures of mounted electronic components can be reduced significantly if heat pipes instead of solid metal plates of sidewall cooling are used to transport the heat generated by electronic components. This paper addresses the above issues and gives recommendations regarding the circuit design that MTBF of a system can be increased. Specific cases of studies are performed to investigate the validity of the proposed methods.

During the construction of the CMS silicon tracker, one of the issues addressed was that of grounding and shielding. The complexity of the system was so unprecedented that many questions had arisen and needed careful evaluation before an answer could be given. In this paper we will describe in particular the problems encountered and the solutions adopted for the silicon Tracker Inner Barrel (TIB).

We describe the design and performance of a prototype instrument with capabilities for both imaging and spectroscopy of sources of 1-10 MeV neutrons. The laboratory prototype is composed of custom-designed liquid scintillator detectors and employs measurements of double neutron-proton scattering to determine the direction and energy of incident neutrons. The detectors provide measurements of the position, energy deposit and pulse shape for each interaction. Pulse shape discrimination and a time-of-flight measurement between coincident interactions in two detectors are used to identify the neutron events, reject background due to Compton scattered gamma radiation and provide a measure of the scattered neutron energy. Calculations employing double n-p scattering kinematics are used to accumulate images and spectra of the neutron source. The quality of these images and spectra is correlated with the energy, position and timing resolution of the detectors. The prototype instrument achieves ~5deg angular resolution and 20% energy resolution (1sigma). This paper presents the design and the most recent results.

A new online system of the underground neutrino detector, Super-Kamiokande is scheduled to be introduced in 2008 together with front-end electronics. This detector is equipped with about 13000 photo-multipliers (PMTs) to detect Cherenkov light generated in the water. In the new data acquisition scheme, we will not use a hardware event-trigger but read out every hit data from the front-end electronics and process them by the online farm. Therefore, there is no threshold of the number of PMT hits and the detector will become more sensitive to important cosmic-ray events such as relic neutrino from supernova and low energy solar neutrino. The test of the prototype online system together with new electronics has been done using the part of Super-Kamiokande detector. In this paper, the design of the upgraded online system and the results of those testing activities will be described.

In this paper we present a system-on-chip (SoC) designed to offer a self-contained, compact data acquisition platform for particle detector monitoring. With a companion ADC, this architecture is capable to acquire the detector's signals, process the data and perform monitoring tests. The SoC is based on a custom, expanded version of a free, open-source 8-bit microprocessor. We extended the instruction set, added internal memory resources and integrated peripherals to interface the core with the external ADC. Peripherals implement in hardware threshold checking, pedestal suppression, waveform recording and a multi-channel analyzer. The SoC inherits from the open-source core some attractive features for real-time applications: high working frequency, constant instruction execution time, short and fixed IRQ latency and little logic resources requirement. The processor makes it possible to execute in software additional off-line data processing, such as averaging, FWHM calculation and peak finding. It includes an 8-bit I/O bus for interfacing with external logic and a UART for RS232 communications. We also present two implementations of the SoC: on a Virtex II Xilinx FPGA and on a standard-cell CMOS 0.18 mum ASIC. Their resource occupation and performance are compared, in the view of a deployment in the monitoring system of an experimental apparatus.

This paper describes a novel estimation method for the parameters of the temporal perfusion model. We investigate the performance of the new reconstruction method using a simple software perfusion phantom and different parametric time depended models. The obtained results demonstrate the potential of the method to provide perfusion imaging within the interventional suite by means of rotational C-arm shaped X-ray systems.

A Gas Electron Multiplier with a thick insulator such as a 100 mum or 150 mum thick insulator (Thick-GEM) has been developed by dry etching successfully in Japan. The electric field inside a hole of the Thick-GEM was calculated and the basic properties of the Thick-GEM were measured. A much stronger electric field can be realized inside the hole of the Thick-GEM than that of a GEM with a 50 mum thick insulator (Standard-GEM). The Thick-GEM can attain much higher gain than the Standard-GEM and has a good gain stability within 1.0% for 9 hours. In this paper, the characteristics of the Thick-GEM are described compared with the Standard-GEM.

Pinhole SPECT can provide high-resolution image with high sensitivity when a collimator is close to an object. However, truncation causes artifact and decreases quantitative accuracy. Defrise et al proposed new reconstruction theory to prevent overestimation due to truncation. In this paper, we applied Defrise theory to three-dimensional pinhole SPECT reconstruction and validated our implementation by computer simulation.