The ion photon emission microscope (IPEM), a new radiation effects microscope for the imaging of single event effects
from penetrating radiation, is being developed at Sandia National Laboratories and implemented on the 88" cyclotron at
Lawrence Berkeley National Laboratories. The microscope is designed to permit the direct correlation between the
locations of high-energy heavy-ion strikes and single event effects in microelectronic devices. The development of this
microscope has required the production of a robust optical system that is compatible with the ion beam lines, design and
assembly of a fast single photon sensitive measurement system to provide the necessary coincidence, and the
development and testing of many scintillating films. A wide range of scintillating material for application to the ion
photon emission microscope has been tested with few meeting the stringent radiation hardness, intensity, and photon
lifetime requirements. The initial results of these luminescence studies and the current operation of the ion photon
emission microscope will be presented. Finally, the planned development for future microscopes and ion luminescence
testing chambers will be discussed.
J. Reijonen, N. Andresen, F. Gicquel, R. Gough, M. King, T. Kalvas, K.-N. Leung, T.-P. Lou, H. Vainionpaa, A. Antolak, D. Morse, B. Doyle, G. Miller, M. Piestrup
We report here on the development of neutron and photon sources for use in imaging and active interrogation
applications, where there is a growing urgency for more advanced interrogation tools. These devices include high yield
D-D, D-T and T-T fusion reaction based neutron generators and also low energy nuclear reaction based high-energy
gamma generators. One common feature in these various devices is the use of a high-efficiency, RF-induction discharge
ion source. This discharge method provides high plasma density for high output current, high atomic species from
molecular gases for high efficiency neutron or gamma generation and long lifetime. Predictable discharge characteristics
of these plasma generators allow accurate modeling for both the beam dynamics and for the heat loads at the target spot.
Current status of the neutron and gamma generator development with experimental data will be presented.
Sandia is evaluating methods for identifying and quantifying trace signatures in field collection samples to support national deterrence policies. The first step in this process is to identify which combination of major, minor, and trace elements in a recovered collection sample provides the most reliable forensic information, and then to be able to quickly, accurately, and, in some cases, nondestructively measure these components. Conventional approaches have typically required a long, complex series of sample preparations followed by radiochemical analysis, often yielding only qualitative results. We report on our investigations to assess accelerator-based ion beam analysis methods by cross-calibrating with other methods, performing in-air analyses of bagged samples in anticipation of inspecting poorly constituted radioactive materials, and quantifying the uncertainties for detected elements.
High-energy photons and neutrons can be used to interrogate for heavily shielded fissile materials inside sealed cargo containers by detecting their prompt and/or delayed fission signatures. The FIND (Fissmat Inspection for Nuclear Detection) active interrogation system is based on a dual neutron+gamma source that uses low-energy (< 500 keV) proton- or deuteron-induced nuclear reactions to produce high intensities of mono-energetic gamma rays and/or neutrons. The source can be operated in either pulsed (e.g., to detect delayed photofission neutrons and gammas) or continuous (e.g., detecting prompt fission signatures) modes. For the gamma-rays, the source target can be segmented to incorporate different (p,γ) isotopes for producing gamma-rays at selective energies, thereby improving the probability of detection. The design parameters for the FIND system are discussed and preliminary accelerator-based measurements of gamma and neutron yields, background levels, and fission signals for several target materials under consideration are presented.
Ion Beam Induced Charge Collection (IBICC) is a proven albeit relatively new method to measure the electronic transport properties of room temperature radiation detectors. Using an ion microbeam, the charge collection efficiency of CZT detectors can be mapped with submicron resolution and maps of the electron mobility and lifetime can be calculated. The nuclear microprobe can be used not only for characterizing detectors but also with the use of Time Resolved IBICC (TRIBICC) and lateral IBICC/TRIBICC we can deduce information about the electron and hole mobility and lifetime profiles, and about the variation of electric field along the detectors' axes. The Sandia Nuclear Microprobe has been and is being used routinely to characterize CZT detectors and measure their electronic transport properties. In this paper we will present the results of these measurements for different detectors. Furthermore the damage effects caused by the probing beam will be discussed and a simple model will be presented to explain the characteristic charge collection efficiency pattern observed after high dose irradiation.
The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide is reviewed and supplemented in the case of CZT by new alpha particle data. CZT strip detectors exposed to intermediate energy proton fluences exhibit increased interstrip leakage after 1010 p/cm2 and significant bulk leakage after 1012 p/cm2. CZT exposed to 200 MeV protons shows a two-fold loss in energy resolution after a fluence of 5 X 109 p/cm2 in thick planar devices but little effect in 2 mm devices. No energy resolution effects were noted from moderated fission spectrum neutrons after fluences up to 1010 n/cm2, although activation was evident. Exposures of CZT to 5 MeV alpha particle at fluences up to 1.5 X 1010 (alpha) /cm2 produced a near linear decrease in peak position with fluence and increases in FWHM beginning at about 7.5 X 109 (alpha) /cm2.
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