2011 DPP Meeting
DPP 2011 Meeting Abstracts
Upgrades to a Table-top System for Characterizing ICF Charged Particle Detectors
Hannah Miller, Kristina Punzi, John Dermigny, Kurt Fletcher, Stephen Padalino; SUNY Geneseo T. Craig Sangster; Laboratory for Laser Energetics
A simple, high-current system has been assembled to test and calibrate charged particle detectors for ICF. A duoplasmatron ion source system produces 0-30 keV deuterons that are focused by an einzel lens and strike a deuterated polyethylene target, initiating the 2H(d,p)3H and 2H(d,n)3He reactions. An upgrade of the system is underway to increase the count rate for the fusion products. The main challenge is the stability of the polymer target, which melts and disintegrates under bombardment by the intense (1 mA) beam. Using a thermocouple system to monitor the target temperature, modifications to the water-cooled target mount and different target designs have been studied. In addition, a Wien filter has been installed downstream of the einzel lens to ensure that the ion beam is well characterized. The deflection of the individual electric and magnetic fields of the Wien filter have been measured and compared to calculated values.
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics
Optimization of Neutron Activation of Carbon at the NIF
S. Padalino, D. Polsin, M. Russ; SUNY Geneseo T. Craig Sangster; Laboratory for Laser Energetics
To determine the rhoR of ignition scale targets at the NIF, a carbon activation diagnostic is being developed to measure tertiary neutron yield. It has been shown theoretically that the ratio of the tertiary yield to the primary yield is directly related to rhoR and is nearly independent of hot-spot electron temperature. Due to carbon’s 20.3 MeV reaction threshold, it is insensitive to 14.7 MeV primary neutrons which are measured by other means and allows for an unambiguous determination of the tertiary to primary ratio. The energy distribution of the 20 to 30 MeV DT neutrons folded with the (n,2n) cross section in this energy region determines the degree in which carbon will be activated. However, the published 12C(n,2n) cross sections in this energy range are bifurcated. To set upper and lower limits on the sensitivity of the activation diagnostic, a finite element calculation was used to determine the limits of the method’s usefulness at differing primary yields and solid angles for the NIF chamber. It was further used to verify MCNPX activation calculations.
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics
A possible 12C(n,2n)11C total cross section measurement
Andrew Evans, Keith Mann, Mark Yuly; Houghton College T. Craig Sangster; Laboratory for Laser Energetics
Tertiary neutron production can be used as an indicator of the burn fraction of a deuterium-tritium pellet in inertial confinement fusion reactions. One way to monitor tertiary neutrons is by carbon activation using the 12C(n,2n)11C reaction, which has a threshold of 20.3 MeV and so is insensitive to primary neutrons produced in the DT reaction. However, the cross section for this reaction is not well known. Several different experimental techniques for measuring 12C(n,2n) have been examined, with an activation experiment being the most feasible.
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics
A Retrieval System for Radioactive Target Materials at the NIF
K. Shibata, M. Krieger, J. Fallica, R. Henchen, E. Pogozelski, S. Padalino; SUNY Geneseo T.C. Sangster; Laboratory for Laser Energetics
Currently, solid radioactive material collection from the NIF target chamber is performed via the DIM. The retrieval process takes several hours to complete. To decrease this time for short lived radioisotopes, the Target Materials Retrieval System (TMRS) is being designed to move a radioactive sample from the target chamber to the counting station in less than 50 seconds, using a closed-loop helium filled RaPToRS system. The TMRS consists of three components: the retrieval apparatus, RaPToRS and the counting station. Starting at 0.5 meters from TCC, the sample will move from the vacuum chamber, travel through 60 meters of 10 centimeter diameter RaPToRS tubes, reaching speeds of 10 m/s. The sample will then arrive at the counting station, where it be robotically placed in front of a gamma ray detector. The use of helium will decrease background gamma radiation produced by activated N2 normally found in a pressurized air system.
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics
Performance Characterization of RaPToRS Systems
K. Shibata, M. Krieger, J. Fallica, R. Henchen, E. Pogozelski, S. Padalino; SUNY Geneseo T.C. Sangster; Laboratory for Laser Energetics
The Rapid Pneumatic Transport of Radioactive Samples (RaPToRS) system can quickly and efficiently move radioactive materials from their activation site to a counting station. Facilities such as the NIF and LLE are considering these systems while NRL is currently using one. The system is essentially a 10 cm diameter pneumatic tube with a cylindrical sample carrier. The performance of the system depends on many factors, including the mass of the carrier, length of the tube, angle and difference in height of the tube’s endpoints, the carrier’s physical design, and the number, type, and distribution of blowers attached to the tube. These factors have been systematically examined to develop the fastest and most reliable system. The most significant factors are the mass and the vertical travel of the carrier. When the carrier mass is low, moving air supports the carrier in the tube, resulting in low friction. The terminal velocity ranges from 13.5 to 2.5 m/s for masses varying from 1 kg to 3 kg. Using a single 1100 W blower, the initial force exerted on the carrier was 11.3 N.
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics
Calibration of the response of radiochromic film to monoenergetic ion beams from a 1.7 MV Pelletron accelerator
C.R. Stillman, K.R. Crompton, M.J. Schepis, C.G. Freeman, S.J. Padalino; SUNY Geneseo T.C. Sangster; Laboratory for Laser Energetics
Radiochromic film (RCF) is used to study protons and other ions that are accelerated from the rear side of targets illuminated with ultra-intense laser light. An experiment is underway to characterize the response of RCF to protons, deuterons, and alpha particles of various energies using the 1.7 MV tandem Pelletron accelerator at SUNY Geneseo. A monoenergetic ion beam from the accelerator is incident on a thin (0.1 ?m) gold foil placed in the center of a 28-inch diameter scattering chamber. A strip of RCF is positioned in a circular arc that is centered on the gold foil. The ion beam strikes the gold foil, causing the RCF to be exposed to elastically backscattered ions. The scattered ion fluence on the RCF strip varies as a function of the scattering angle. After removal from the chamber, the RCF is scanned in transmission mode using an Epson 10000 XL flatbed scanner. The red channel of the resulting scan is used to determine the optical density of the film. The output from the flatbed scanner is cross calibrated with a precision microdensitometer (PDS).
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics
IViPP: A Tool for Visualization in Particle Physics
Hieu Tran, Elizabeth Skiba, Doug Baldwin; SUNY Geneseo T.C. Sangster; Laboratory for Laser Energetics
Experiments and simulations in physics generate a lot of data; visualization is helpful to prepare that data for analysis. IViPP (Interactive Visualizations in Particle Physics) is an interactive computer program that visualizes results of particle physics simulations or experiments. IViPP can handle data from different simulators, such as SRIM or MCNP. It can display relevant geometry and measured scalar data; it can do simple selection from the visualized data. In order to be an effective visualization tool, IViPP must have a software architecture that can flexibly adapt to new data sources and display styles. It must be able to display complicated geometry and measured data with a high dynamic range. We therefore organize it in a highly modular structure, we develop libraries to describe geometry algorithmically, use rendering algorithms running on the powerful GPU to display 3-D geometry at interactive rates, and we represent scalar values in a visual form of scientific notation that shows both mantissa and exponent.
*Funded in part by a grant from the DOE through the Laboratory for Laser Energetics