Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session PD: Nuclear Instrumentation IV |
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Chair: Kyle Leach, Colorado School of Mines Room: Junior Ballroom C |
Sunday, October 16, 2016 10:30AM - 10:42AM |
PD.00001: CHICOx; an auxiliary detector for GRETA for nuclear gamma-ray spectroscopic study Ching-Yen Wu A proposal has been submitted to DOE/NP to upgrade CHICO2 to CHICOx, by resizing the detector chamber and reconfiguring the pixelated position-sensing board, to be fully integrated into GRETA. The recently completed CHICO2, a two-dimensional pixelated parallel-plate avalanche counter, has achieved a position resolution matching to that of GRETA and has been integrated successfully into GRETINA. Based on the success of the science campaign in FY14/15 at ANL using GRETINA/CHICO2, we believe this proposed upgrade will fully exploit the sensitivity of GRETA for the nuclear gamma-ray spectroscopic study using the quasi-elastic reactions such as the sub-barrier Coulomb excitation method and few-nucleon transfer reaction as well as the deep-inelastic reaction. GRETA/CHICOx will be a unique instrument providing the highest sensitivity in studying the evolution of shell structure and collectivity for neutron-rich nuclei near the r-process path. The upgrade plan together with the timeline will be presented. [Preview Abstract] |
Sunday, October 16, 2016 10:42AM - 10:54AM |
PD.00002: Inverted Coaxial HPGe Segmented Point Contact Detector Marco Salathe, Heather Crawford, Ren Cooper, David Radford The inverted coaxial segmented HPGe point contact detector \footnote{A novel HPGe detector for gamma-ray tracking and imaging. R.J. Cooper, D.C. Radford, P.A. Hausladen, K. Lagergren. Nucl.\ Instr.\ and Meth.\ A 665 (2011) 25-32} is a new device being characterized for use in gamma-ray tracking arrays. It is expected to have an excellent position resolution, particularly for simultaneously occurring multiple interactions. However, the characteristic long charge carrier drift path of this technology, combined with trapping and loss of charge carriers, leads to a degradation of the energy resolution. A prototype produced from n-type material, consisting of 20 segments, has been characterized in a lab environment with a variety of collimated and uncollimated sources. Results from this study show that the signal decomposition from this detector not only allows the reconstruction of the interaction positions, but also can be used to correct the degraded energy resolution and restore the characteristic HPGe resolution. [Preview Abstract] |
Sunday, October 16, 2016 10:54AM - 11:06AM |
PD.00003: Simulating the DESCANT Neutron Detection Array with the Geant4 Toolkit Joseph Turko, Vinzenz Bildstein, Evan Rand, Andrew MacLean, Paul Garrett The DEuterated SCintillator Array for Neutron Tagging (DESCANT) is a newly developed high-efficiency neutron detection array composed of 70 hexagonal deuterated scintillators. Due to the anisotropic nature of elastic (n,d) scattering, the pulse-height spectra of a deuterated scintillator contains a forward-peaked structure that can be used to determine the energy of the incident neutron without using traditional time-of-flight methods. Simulations of the array are crucial in order to interpret the DESCANT pulse heights, determine the efficiencies of the array, and examine its capabilities for conducting various nuclear decay experiments. To achieve this, we plan: (i) a verification of the low-energy hadronic physics packages in Geant4, (ii) a comparison of simulated spectra with data from a simple cylindrical ``test can'' detector geometry, (iii) expanding the simulated light response to a prototype DESCANT detector, and (iv) simulating the entire DESCANT array. [Preview Abstract] |
Sunday, October 16, 2016 11:06AM - 11:18AM |
PD.00004: GRIFFIN's Fast-Timing Array Bruno Olaizola The Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei~(GRIFFIN) is the new $\beta$-decay spectrometer facility at TRIUMF-ISAC. Consists of an array of 16 large-volume HPGe clover detectors with an unparalleled efficiency of $19\%$ at 1.33~MeV. Its strongest advantage is the versatility of the ancillary detectors that can be coupled to the main array to tag on $\beta$ particles, neutrons or precisely measure conversion electron spectra. An ancillary array of 8 LaBr$_3$(Ce) detectors for $\gamma$-rays and a fast plastic scintillator for $\beta$-particles has been optimized for fast-timing experiments with GRIFFIN. The 51 mm x 51 mm cylindrical LaBr$_3$(Ce) crystals are coupled to Hamamatsu R2083 photomultipliers. Timing resolutions as good as FWHM$\sim200$~ps and time-walks below $\pm30$~ps have been obtained for individual crystals using analog electronics. There is also an ongoing project to develop an active BGO shield for the LaBr$_3$(Ce) crystals. The LaBr$_3$(Ce) array commissioning experiment to measure the $^{145,146}$Cs decay to $^{145,146}$Ba will test its capabilities over a wide range of lifetimes. Preliminary results on the lifetimes of some of the low-laying states will be presented. [Preview Abstract] |
Sunday, October 16, 2016 11:18AM - 11:30AM |
PD.00005: The first measurements using GODDESS S. D. Pain, A. Ratkiewicz, T. Baugher, M. Febbraro, J. A. Cizewski Direct reaction measurements, such as transfer, inelastic scattering, and charge-exchange reactions, are well-established probes of nuclear structure. Measurements are often made in inverse-kinematics, a technique applicable to both stable and radioactive beams, using large-area charged-particle detectors. There are trade-offs between optimizing for charged-particle or gamma-ray detection - especially gamma-ray efficiency and charged-particle angular resolution. GODDESS (Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies) is a coupling of a $\sim$ 700-channel highly-segmented silicon detector array (based on ORRUBA) with the Gammasphere HPGe array. Gammasphere, has an unusually large internal geometry ( 14'' cavity), allowing a full implementation of a large well-optimized charged-particle array. GODDESS provides charged-particle detection with $\sim 1^\circ$ resolution in polar angle, between $15^\circ$ and $165^\circ$ ($\sim 80\%$ azimuthal coverage), with a few tens of keV energy resolution. A compact fast ionization chamber is incorporated for measurement of beam-like species at zero degrees. The first campaign of in-beam measurements with GODDESS was conducted July-September 2015. Details of GODDESS and the commissioning experiment will be presented. [Preview Abstract] |
Sunday, October 16, 2016 11:30AM - 11:42AM |
PD.00006: Proton Transfer Reactions Studied Using the VANDLE Neutron Detector Array C.R. Thornsberry, S. Burcher, R. Gryzwacz, K.L. Jones, S.V. Paulauskas, K. Smith, M. Vostinar, J. Allen, D.W. Bardayan, D. Blankstein, J. deBoer, M. Hall, P.D. O'Malley, C. Reingold, W. Tan, J.A. Cizewski, A. Lepailleur, D. Walter, M. Febbraro, S.D. Pain, S.T. Marley Proton transfer reactions, such as (d,n), are powerful tools for the study of single particle proton states of exotic nuclei. Measuring the outgoing neutron allows for the extraction of spectroscopic information from the recoil nucleus. With the development of new radioactive ion beam facilities, such as FRIB in the U.S., comes the need for new tools for the study of reactions involving radioactive nuclei. Neutron detectors, such as VANDLE, are sensitive to gamma rays in addition to neutrons. This results in high background rates for measurements with high external trigger rates. The use of discriminating recoil particle detectors, such as phoswich detectors, allow for the selection of a clean recoil tag by separating the recoil nucleus of interest from unreacted RIB components. Developments of low energy proton transfer measurements in inverse kinematics and recent (d,n) results will be presented. [Preview Abstract] |
Sunday, October 16, 2016 11:42AM - 11:54AM |
PD.00007: Development of tracking detectors for light secondary exotic beams Christina Gay, Jolie Cizewski, Steven Pain, Michael Febbraro, Frederic Sarazin, Raymond Kozub, Kyle Schmitt, David Walter, Dominic Robe, Travis Johnson, Brett Manning, Sergey Ilyushkin, Patrick O'Malley Understanding of the single-particle structure of radioactive nuclei is important both for discerning the evolution of nuclear structure away from stability, and to provide an indirect constraint on reaction rates in astrophysical environments. Single-nucleon transfer reaction experiments measured in inverse kinematics, probe the single-particle structure away from stability. Some of the most intense beams currently available are produced through the in-flight technique, at facilities such as TwinSol at Notre Dame and the NSCL. However, in-flight beams suffer from poor emittance, typically resulting in large beam spot sizes that impact the angular resolution, and hence center-of-mass energy resolution. This limitation can be diminished through the use of multi-wire gas-filled tracking detectors placed upstream of the target, enabling event-by-event measurement of the beam particle trajectories, thereby reducing the effective beam spot size. Details of the tracking detector and prototype testing will be presented. This work is supported in part by the U.S. DOE and NSF. [Preview Abstract] |
Sunday, October 16, 2016 11:54AM - 12:06PM |
PD.00008: ABSTRACT WITHDRAWN |
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