Three dimensional photograph of single electron tracks through a scintillator

The reconstruction of particle trajectories makes it possible to distinguish between different types of charged particles. In high-energy physics, where trajectories are rather long, large size trackers must be used to achieve sufficient position resolution. However, in low-background experiments tracks are rather short and three dimensional trajectories could only be resolved in time-projection chambers so far. For detectors of large volume and therefore large drift distances, which are inevitable for low-background experiments, this technique is limited by diffusion of charge carriers. In this work we present a "proof-of-principle" experiment for a new method for the three dimensional tracking of charged particles by scintillation light: We used a setup consisting of a scintillator, mirrors, lenses and a novel imaging device (the hybrid photo detector) in order to image two projections of electron tracks through the scintillator. We took data at the T-24 beam-line at DESY with relativistic electrons with a kinetic energy of 5 GeV and from this data successfully reconstructed their three dimensional propagetion path in the scintillator. With our setup we achieved a position resolution of about 28 mum in the best case.Comment: 9 pages, 13 figures, 1 tabl

An integrated circuit/microsystem/nano-enhanced four species radiation sensor for inexpensive fissionable material detection

Small scale radiation detectors sensitive to alpha, beta, electromagnetic, neutron radiation are needed to combat the threat of nuclear terrorism and maintain national security. There are many types of radiation detectors on the market, and the type of detector chosen is usually determined by the type of particle to be detected. In the case of fissionable material, an ideal detector needs to detect all four types of radiation, which is not the focus of many detectors. For fissionable materials, the two main types of radiation that must be detected are gamma rays and neutrons. Our detector uses a glass or quartz scintillator doped with 10B nanoparticles to detect all four types of radiation particles. Boron-10 has a thermal neutron cross section of 3,840 barns. The interaction between the neutron and boron results in a secondary charge particle in the form of an alpha particle to be emitted, which is detectable by the scintillator. Radiation impinging on the scintillator matrix produces varying optical pulses dependent on the energy of the particles. The optical pulses are then detected by a photomultiplier (PM) tube, creating a current proportional to the energy of the particle. Current pulses from the PM tube are differentiated by on-chip pulse height spectroscopy, allowing for source discrimination. The pulse height circuitry has been fabricated with discrete circuits and designed into an integrated circuit package. The ability to replace traditional PM tubes with a smaller, less expensive photomultiplier will further reduce the size of the device and enhance the cost effectiveness and portability of the detector

Report of the x ray and gamma ray sensors panel

Overall five major areas of technology are recommended for development in order to meet the science requirements of the Astrotech 21 mission set. These are: detectors for high resolution gamma ray spectroscopy, cryogenic detectors for improved x ray spectral and spatial resolution, advanced x ray charge coupled devices (CCDs) for higher energy resolution and larger format, extension to higher energies, liquid and solid position sensitive detectors for improving stopping power in the energy range 5 to 500 keV and 0.2 to 2 MeV. Development plans designed to achieve the desired capabilities on the time scales required by the technology freeze dates have been recommended in each of these areas

Charge-coupled devices with fast timing for astrophysics and space physics research

A charge coupled device is under development with fast timing capability (15 millisecond full frame readout, 30 microsecond resolution for measuring the time of individual pixel hits). The fast timing CCD will be used in conjunction with a CsI microfiber array or segmented scintillator matrix detector to detect x rays and gamma rays with submillimeter position resolution. The initial application will be in conjunction with a coded aperture hard x ray/gamma ray astronomy instrument. We describe the concept and the readout architecture of the device

The development of a cost-effective beam loss monitor for use at the K600 magnetic spectrometer at iThemba LABS

Includes abstract.Includes bibliographical references (leaves 69-70).The purpose of this work was to develop a cost-effective beam loss monitor for use at the K600 magnetic spectrometer at iThemba LABS. To this end. the commonly used materials and technologies were reviewed and photo diodes were chosen because of their low price, high performance and ready availability. Experiments have been carried out and compared to theoretical calculations. Recommendations for future developments are presented

A Low Jitter and Low Power Electronic Interface for Time-of-Flight Positron Emission Tomography Silicon Photomultiplier Detectors

A time-of-flight (TOF) detection system for a silicon photomultiplier (SiPM) is designed for the purpose of improving on existing technology for applications in positron emission tomography, with an emphasis on low power and low timing jitter. A reconstruction algorithm is implemented in Matlab to demonstrate the effect of TOF on the image quality per number of source events, as compared to systems restricted to line-of-response (LOR) data only. A case study is performed on SiPM functionality, behavioral modeling, and contemporary front-end amplification designs for a SiPM detector. A charge sensitive amplifier (CSA) circuit is modified for simultaneous collection of timing and energy information, implementing a novel hybrid current-division scheme by capacitively coupling the SiPM to the CSA so that the SiPM\u27s fast leading edge behavior and linear energy-charge correlation is preserved, while conserving power and minimizing jitter. Simulations provide the proof of concept for this design, operating at under 600 μW of power, and injecting less than 60 ps of jitter into the timing output signal. Preliminary testing is conducted using a specialized integrated circuit with analog input CSA channels to verify operation. An energy resolution of 11.7 % was achieved for the 511 keV peak of a Na-22 source, and 10.9 % for the 662 keV peak of a Cs-137 source, using an ON Semiconductor 3mm SiPM and a LYSO scintillator. Advisors: Sina Balkir and Michael Hoffma

Fast Timing Bi-Directional Charge Coupled Devices for Use in Gamma -Ray Astronomy.

A Charge Coupled Device (CCD) coupled with a pixellated inorganic scintillator (such as segmented CsI) can provide high position resolution (∼300 mum). However, standard CCDs are integrating devices typically operating no faster than video rates. For a balloon-borne gamma-ray telescope capable of measuring the energy of individual photons, the CCD must have a time resolution better than the average time interval between cosmic ray events on the veto shield (∼10 kHz). A Fast Timing Bi-Directional CCD has better than 10 mus time resolution and 50 mum position resolution. We describe the CCD readout architecture, the ASIC readout design, the present status of the development, and the application to a gamma-ray astronomy telescope suitable for a 100-day Ultra Long Duration Balloon mission

FABRICATION, MEASUREMENTS, AND MODELING OF SEMICONDUCTOR RADIATION DETECTORS FOR IMAGING AND DETECTOR RESPONSE FUNCTIONS

In the first part of this dissertation, we cover the development of a diamond semiconductor alpha-tagging sensor for associated particle imaging to solve challenges with currently employed scintillators. The alpha-tagging sensor is a double-sided strip detector made from polycrystalline CVD diamond. The performance goals of the alpha-tagging sensor are 700-picosecond timing resolution and 0.5 mm spatial resolution. A literature review summarizes the methodology, goals, and challenges in associated particle imaging. The history and current state of alpha-tagging sensors, followed by the properties of diamond semiconductors are discussed to close the literature review. The materials and methods used to calibrate the detector readout, fabricate the sensor, perform simulations, take measurements, and conduct data analysis are discussed. The results of our simulations and measurements are described with challenges and interpretations. The first part of the dissertation is concluded with potential solutions to challenges with our diamond alpha-tagging sensor design, recommendations of work to help further verify or refute diamonds viability for alpha tagging in associated particle imaging. In the second part of this dissertation, we cover the development of a high-purity germanium detector response function for the Los Alamos National Laboratory Detector Response Function Toolkit. The goal is to accurately model the pulse-height spectra measured by semiconductor radiation detectors. The literature review provides information on high-purity germanium radiation detectors and semiconductor charge transport kinematics. The components of the electronic readout and their effect on radiation measurements are discussed. The literature review ends with a discussion on different methods for building detector response functions. In the methods section, we explain our methodology for building detector response functions. This includes models of radiation transport, electrostatics, charge transport, and electronic readout components. Within the methods section, there are results from individual components to demonstrate their functionality. The results section is reserved for demonstrating the use of the detector response function as a whole. We provide the modeled pulse-height spectra for different radiation sources and user input parameters. These are compared to experimentally measured datasets. The second part of the dissertation concludes with a discussion of the benefits, drawbacks, and future improvements that could be made

Soft Gamma-ray Detector for the ASTRO-H Mission

ASTRO-H is the next generation JAXA X-ray satellite, intended to carry instruments with broad energy coverage and exquisite energy resolution. The Soft Gamma-ray Detector (SGD) is one of ASTRO-H instruments and will feature wide energy band (40-600 keV) at a background level 10 times better than the current instruments on orbit. SGD is complimentary to ASTRO-H's Hard X-ray Imager covering the energy range of 5-80 keV. The SGD achieves low background by combining a Compton camera scheme with a narrow field-of-view active shield where Compton kinematics is utilized to reject backgrounds. The Compton camera in the SGD is realized as a hybrid semiconductor detector system which consists of silicon and CdTe (cadmium telluride) sensors. Good energy resolution is afforded by semiconductor sensors, and it results in good background rejection capability due to better constraints on Compton kinematics. Utilization of Compton kinematics also makes the SGD sensitive to the gamma-ray polarization, opening up a new window to study properties of gamma-ray emission processes. The ASTRO-H mission is approved by ISAS/JAXA to proceed to a detailed design phase with an expected launch in 2014. In this paper, we present science drivers and concept of the SGD instrument followed by detailed description of the instrument and expected performance.Comment: 17 pages, 15 figures, Proceedings of the SPIE Astronomical Instrumentation "Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray