Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session K15: Nuclear Instrumentation II and Nuclear Applications |
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Sponsoring Units: DNP Chair: Jeffrey Martoff, Temple University Room: Hyatt Regency Jacksonville Riverfront City Terrace 11 |
Sunday, April 15, 2007 1:15PM - 1:27PM |
K15.00001: Micromegas gain and stability in negative ion drift chamber Michael Dion, C.J. Martoff, Michael Hosack Drifting negative ions rather than electrons is a new operating mode for Time Projection Chambers (TPCs) and related gas detectors. Diffusion in these devices is then suppressed to the thermal limit in all three dimensions without magnetic field, and continues to fall with increasing drift field up to E/p values of several tens of V/cm*Torr. The stability at high E/p is also improved by the electronegative gas. Newer TPC designs incorporate micropattern detectors as gain elements, and our group has been testing GEMs and MicroMegas in negative ion gas mixtures. The present report describes significant differences in the stability and performance of GEM vs. Micromegas detectors operating in negative ion gas mixtures based on carbon disulfide. [Preview Abstract] |
Sunday, April 15, 2007 1:27PM - 1:39PM |
K15.00002: Quartz Plate Calorimeter Prototype Ugur Akgun The Cerenkov calorimeters are effective solutions to the high radiation environment of the future hadron colliders. We designed and built a Cerenkov calorimeter prototype that consists of 20 layers of quartz plates and iron absorbers between them. In this report we present the results from the test beam performed at CERN H2 area with various energies of electron and pion beams. The hadronic and electromagnetic energy resolutions, signal collection uniformity, and linearity of the calorimeter are presented as well as the Geant4 simulations. [Preview Abstract] |
Sunday, April 15, 2007 1:39PM - 1:51PM |
K15.00003: Development of inorganic nanocomposite scintillators for gamma-ray detection Minesh K. Bacrania, D. Wayne Cooke, Rico E. Del Sesto, Robert D. Gilbertson, Edward A. McKigney, Ross E. Muenchausen, Kevin C. Ott, Melissa A. Siemens, Sy Stange Inorganic nanocomposite scintillators offer the possibility of combining the robust physical characteristics of plastic scintillator and the spectroscopic power of inorganic single-crystal scintillators. We currently are able to produce lanthanum-halide-based nanocomposite scintillators with volumes of 5--15 cc. This talk will discuss the progress of our scintillator development program, and results of optical and nuclear measurements will be presented. [Preview Abstract] |
Sunday, April 15, 2007 1:51PM - 2:03PM |
K15.00004: Neutron Production via a Pyroelectric Crystal without a Tip W. Tornow, S.M. Shafroth, J.D. Brownridge Recently, Naranjo et al.$^{1}$ and Geuther et al.$^{2}$ reported on the production of neutrons via the $^{2}$H(d,n)$^{3}$He reaction using a pyroelectric crystal with a tungsten tip attached. Here we report that neutrons can also be produced with a simpler version. Our accelerator consisted of a 2.54 cm dia x 2.54 cm LiTaO$_{3}$ crystal placed in D$_{2}$ gas of 2 mTorr without a tip and without a deuterated foil. The D$_{2}$ provided the projectiles and target atoms for the $^{2}$H(d,n)$^{3}$He reaction. When the heated (by a Peltier heater/cooler) crystal was allowed to cool to room temperature, our 12.5 cm dia x 5 cm liquid scintillator based neutron detector equipped with neutron-gamma-ray pulse-shape discrimination electronics counted 6 neutrons per minute compared to a background rate of 2 events per minute. The neutron detector was shielded by about 6 mm of Pb from the very intense X-ray radiation ($\sim $100 mR/h). The maximum ion energy and current were 200 keV and 3 nA, respectively. When H$_{2}$ was substituted for D$_{2}$, no neutron counts above background were detected. $^{1}$B. Naranjo, J.K. Gimzewski, and S. Putterman, Nature 434, 115 (2005) $^{2}$J. Geuther, Y. Danon, and F. Saglime, Phy. Rev. Lett. 96, 054803 (2006) \newline \newline *This work was supported in part by DOE grant DE-FG02-97ER41033. [Preview Abstract] |
Sunday, April 15, 2007 2:03PM - 2:15PM |
K15.00005: Space Radiation a Potential Show Stopper in Missions to Moon and Mars and beyond Ram Tripathi Exposure from the hazards of severe space radiation in deep space/ long duration missions is `the show stopper' for NASA's vision of missions to Moon, Mars and beyond. The key to the success of human exploration and development of space is protecting astronauts, habitat and electronics against the hazards of severe space radiation environment. Accurate risk assessments critically depend on the accuracy of the input information about the interaction of ions with materials, electronics and tissues. This is further augmented by nonexistence of in vivo or in vitro data or studies about continuous long duration exposure of radiation to tissues. Due to paucity of the huge amount of needed experimental input data about the interaction of radiation, it is imperative to develop reliable accurate models of nuclear reactions and structures that form the basic input ingredients. State-of-the-art nuclear cross sections models have been developed at the NASA Langley Research center. The vital role and importance of nuclear physics for space missions would be discussed and a few examples would be presented for space missions. [Preview Abstract] |
Sunday, April 15, 2007 2:15PM - 2:27PM |
K15.00006: Nuclear Fragmentation Processes Relevant for Human Space Radiation Protection Zi-Wei Lin Space radiation from cosmic ray particles is one of the main challenges for human space explorations such as a moon base or a trip to Mars. Models have been developed in order to predict the radiation exposure to astronauts and to evaluate the effectiveness of different shielding materials, and a key ingredient in these models is the physics of nuclear fragmentations. We have developed a semi-analytical method to determine which partial cross sections of nuclear fragmentations most affect the radiation dose behind shielding materials due to exposure to galactic cosmic rays. The cross sections thus determined will require more theoretical and/or experimental studies in order for us to better predict, reduce and mitigate the radiation exposure in human space explorations. [Preview Abstract] |
Sunday, April 15, 2007 2:27PM - 2:39PM |
K15.00007: Stimulated Decay of Isomeric Materials for Sensor Power Marc Litz, Nino Pereira, George Merkel We are exploring the feasibility of using the energy that can be stored in nuclear isomers for driving low-power batteries. We investigate the use of SiC direct-energy-converters, in conjunction with isomeric materials as the power source for long-lived, low-power, low-maintenance battery applications. The paper discusses our selection of the isomer that seems most promising, estimates of the energy cost compared to the alternatives, and the radiation measurements made to date. This approach differs dramatically from suggestions for use of isomeric materials in explosives applications. The fact that an increased decay rate, and energy release, can be stimulated by external radiation is the characteristic of the isomeric state that motivates this effort. Transportation of these energetic materials would be made easier by stimulating the higher decay rate at the point of use. [Preview Abstract] |
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