Application of silicon planar structures for the determination of the spectrum of the proton beams produced by laser-driven proton medical accelerators. Theoretical approach. (#2388)
I. E. Anokhin1, A. Rosenfeld2
1 Institute for Nuclear Research, Kyiv, Ukraine
Development of the laser-driven particle accelerators to produce the proton beams necessary for the nuclear medicine is a rapidly upcoming field. Laser-accelerated proton spectra feature a broad energy spread in comparison with the case of proton beams produced by conventional accelerators. The thin silicon planar p-i-n structures can be used for the diagnostic of such beams due to their real-time readout, compactness and standard fabrication technologies.
In the present work, the application of thin silicon planar p-i-n diodes for the proton spectrum determination of the laser-driven proton beams is theoretically investigated. The method of the proton spectrum reconstruction from the temporal response of the detector irradiated with a single laser-driven proton burst for different distances between proton source of the laser-driven accelerator and detector position has been developed. The temporal response of the detector was modeled for different proton spectrum and variable detector parameters. Based on that optimization of the detector has been proposed.
Keywords: Silicon radiation detectors, Laser-driven particle accelerators, Nuclear medicine
Photon counting with near unity efficiency, ultra-high detection rates, and ultra-high time resolution using superconducting nanowire detectors (#1848)
I. Esmaeil Zadeh1, J. W. N. Los1, G. Bulgarini1, V. Zwiller1, S. N. Dorenbos1
1 Single Quantum, Delft, Netherlands
Photon counters with high efficiency, high time resolution, low dark counts and high photon detection-rates are indispensable elements of optical measurements. Combining all performances in a single device has been a long time challenge. We present a detector that meets all these performance: broadband efficiency higher than 90% in the infrared range, 100 MHz photon detection-rate, dark counts below 150 Hz and timing jitter below 15 ps. The device is based on the breakthrough technology of superconducting nanowire single photon detection (SNSPD). The operation of the detector is based on the transition of a nanowire from the superconductive to the resistive state upon the absorption of at least a single photon. The detectors are pigtailed with an optical fiber and operated in a closed-cycle cryostat at 2.5 Kelvin. This turn-key approach enables continuous operation for up to 10,000 hours and requires no liquid helium consumptio, providing plug and optical measurements. SNSPDs have found important applications in optical communication, information technology, time-resolved spectroscopy, laser ranging and remote sensing (LiDAR). In the field of medical imaging, our device has found application in oxygen singlet detection , providing efficient detection of weak optical signals in the infrared (~1270 nm) to understand processes at the basis of photodynamic cancer treatments. In the near future, we envision SNSPD as crucial photon detectors for the development of novel advanced optical techniques for medical imaging where photon conting, high sensitivity, fast time response and low noise are required.
Keywords: New detectors ; superconducting nanowire; photon counter; high efficiency ; infrared spectroscopy ; timing jitter ; optical detector ; optical tomography ;
CdZnTe sensors for Photon Counting CT (PCCT) applications. (#3625)
G. Prekas1, N. Sadeghi1, S. Taherion1, R. Grill2, U. El-Hanany1
1 Redlen Technologies, R&D, Saanichton, British Columbia, Canada
Recent advancements in photon counting based imaging and ongoing progress in medical CT have increased the demand for high quality sensors that meet the challenging and unique requirements of this imaging modality. Among the potential detector technologies and material candidates, semi-insulating CdZnTe crystals, grown by THM method and fabricated into sensors at Redlen Technologies, have demonstrated great ability to operate under the intense, dynamic and rapidly changing irradiation environments required by the photon counting CT scanners. In this talk we will review the major underlying mechanisms and challenges involved during the sensor operation under these intense X-ray conditions. Concluding, we will highlight the major technological advancements made over the past few years in order to overcome these and achieve the present state of the art sensors.
Keywords: CdZnTe, Photon counting, CT, polarization, stability
SPECT Reconstruction and Analysis for the Inspection of Spent Nuclear Fuel (#3418)
M. Mayorov1, T. A. White1, N. Deshmukh3, L. E. Smith3, E. Miller3, J. Dahlberg2, T. Honkamaa4, R. S. Whittman3
1 International Atomic Energy Agency, Department of Safeguards / Non-Destructive Assay Section, Vienna, Wien, Austria
A gamma-emission-tomography (GET) system for the inspection of spent nuclear fuel (SNF) has been developed and tested on multiple fuel types. For dismountable fuel, this tool can be used for verification of the integrity of an assembly and consistency with the declarations of fissile-material content. Parallel-beam line integrals are measured by a discrete array of CdZnTe detectors that view the fuel through a 1.5mm wide by 100mm thick tungsten collimator. Detectors and electronics are on a rotating platform within a watertight stainless steel torus. During operation, the system is underwater and fuel is lowered through the center of the torus and held stationary as data are collected. Tomographic data collection requires a time on the order of minutes. In field experiments, data with count rates in the range of 50kcps to >500kcps per pixel have been recorded. In the reconstructed images, missing or replaced pins in all assembly types can be visually discriminated in the lattice of fuel pins. Automated detection of missing/replaced pins is the metric used for determination of optimal processing steps. Effectiveness of reconstruction and data-processing tools is measured by a tools ability to improve performance on the pin-discrimination task. This paper describes the data preprocessing, image reconstruction, image analysis, and performance evaluation of this system.
Keywords: attenuation correction, gamma-ray emission tomography, image reconstruction, image quality metrics, safeguards, spent nuclear fuel
Design and Characterization of a Low-Noise Analog Front-End Readout Circuit in 0.18 μm CMOS Technology for CZT/Si-PIN Detectors (#3026)
W. Gao1, S. Li1, D. Jiang1, Y. Hu1
1 Northwestern Polytechnical University, Instite of Microelectronics, Xi'an, China
In this paper, we report on the recent development of a low-noise front-end readout ASIC for cadmium zinc telluride (CZT) and/or Si-PIN detectors. The readout chain consists of a charge sensitive amplifier, a CR-(RC)7 pulse shaper and readout buffers. The readout circuits are implemented in TSMC 0.18 μm mixed-signal CMOS technology. The die size of the prototype chip is 2.1 mm × 2.5 mm. At room temperature, the equivalent noise charge of an analog front end readout channel is 114 e- (rms) with the input parasitic capacitance of 0 pF for the average power consumption of 20 mW. The linearity error is less than 3 %. By connecting the readout ASIC to a CZT detector, we obtained the energy resolution of a γ-ray spectrum is 4 % (FWHM) at the 59.5-keV line of 241Am source.
Keywords: Front-End, ASIC, Low Noise, Preamplifier, Pulse Shaper, CZT, Si-PIN
Advances in THM CZT for Gamma Spectroscopy and Imaging Applications (#1614)
H. Chen1, H. Li1, M. Reed1, A. Sundaram1, J. Eger1, B. Harris1, A. Cherlin1, J. Hugg2, I. Radley2
1 eV Products/Kromek-USA, Saxonburg, Pennsylvania, United States of America
Recent progress in the wide bandgap semiconductor detector CdZnTe (CZT) grown by the traveling heater method (THM) coupled with advanced electronics has make this semiconductor an excellent choice for practical mass scale production of commercial application devices such as that for gamma spectroscopy and medical imaging. This paper presents the advances in THM crystal growth technology leading to high yield of uniform, large single crystal and good electrical transport properties material that made the issue of material availability and mass volume production a reality. Single crystal > 850 cm3 can now be achieved. Robust THM CZT-based Coplanar Grid Device (CPG) with room temperature energy resolution near 1% @ 662 keV can now be routinely produced along with many practical medical imaging devices such as thyroid camera and full body SPECT camera. The paper also discusses the State-of-the Art device fabrication include bonding technology that has been enabling these practical applications.
Keywords: CZT, THM, gamma spectroscopy, CPG, medical imaging, crystal growth, semiconductor