Bulletin of the American Physical Society
4th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 59, Number 10
Tuesday–Saturday, October 7–11, 2014; Waikoloa, Hawaii
Session ML: Instrumentation V |
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Chair: Chris Morris, Los Alamos National Laboratory Room: Kona 4 |
Saturday, October 11, 2014 2:00PM - 2:15PM |
ML.00001: Polarized He3 Ion Source for RHIC and eRHIC James Maxwell The addition of a polarized neutron beam source to the Relativistic Heavy Ion Collider at Brookhaven National Laboratory would present promising opportunities for the study of nucleon structure. Polarized neutron collision measurements of transverse spin asymmetries in Drell-Yan scattering would allow a search of the predicted sign switch for u and d quark flavors in the Sivers function. In a future electron-ion collider, precision tests of the Bjorken sum rule could be carried out with both proton and neutron beams. Polarized $^3$He offers an effective polarized neutron beam which is accessible with RHIC spin manipulation. We are developing such a source leveraging metastability exchange optical pumping of $^3$He and utilizing the existing Electron Beam Ionization Source at RHIC. We aim to deliver approximately $1.5 \times 10^{11}$ doubly ionized 3He atoms per pulse at 70\% polarization into RHIC. The source is under development at MIT and BNL and an initial test of the principle is under construction. The source design will be described and the status of the test summarized. [Preview Abstract] |
Saturday, October 11, 2014 2:15PM - 2:30PM |
ML.00002: Recent results from proton polarimetry at RHIC Oleg Eyser The Relativistic Heavy Ion Collider (RHIC) has successfully collided polarized proton beams with momenta as high as 255 GeV/c and polarizations around P$=$60{\%}. The polarization of the proton beams is measured through spin dependent elastic scattering off a polarized hydrogen jet target and similarly monitored with Carbon fiber targets several times through a stored RHIC fill of a few hours duration. With recent advancements in beam luminosities, the largely increased data sets have enabled unprecedented possibilities to study systematic effects in the polarimeters. We will discuss details of different background contributions, properties of the polarized beams, and their implications on systematic uncertainties. This is vital input for spin-dependent measurements at RHIC and extends the polarized world data on polarized elastic proton-proton scattering significantly. [Preview Abstract] |
Saturday, October 11, 2014 2:30PM - 2:45PM |
ML.00003: Progress Towards the Detection of Faraday Rotation on Polarized Helium-3 Wolfgang Korsch, Joshua Abney, Mark Broering, Gretchen Phelps Off-resonance Faraday rotation can conceivably offer a new way of monitoring the nuclear spin polarization of dense polarized helium-3 targets. A very sensitive triple-modulation technique has been devised to detect rotation angles with a sensitivity of a few times 10$^{-8}$ rad. The first goal is to isolate the magnetic contribution to Faraday rotation on a spin-polarized target. The technique has been successfully applied to several test samples. Progress towards the detection of a spin-induced rotation on an optically pumped spin-exchange polarized helium-3 target will be reported. [Preview Abstract] |
Saturday, October 11, 2014 2:45PM - 3:00PM |
ML.00004: Effective production of spin polarization of atoms in superfluid helium using pulsed lasers Miki Hayasaka, Takeshi Furukawa, Hideki Tomita, Takahide Takamatsu, Kei Imamura, Tomomi Fujita, Tohru Kobayashi, Haruko Uematsu, Hideki Ueno, Yukari Matsuo We are developing a new laser spectroscopic technique ``OROCHI'' to determine nuclear spins and moments of RI atoms. In this technique, superfluid helium (He II) is used as a trapping material of short-lived RI atoms. We utilize optical pumping to produce atomic spin polarization, and laser-radio frequency/microwave double resonance method to determine both Zeeman and hyperfine splittings, respectively. In He II spin polarization can be maintained for a long time (\textgreater 2 s in the case of Cs), which enables us to produce high degree of spin polarization. As for optical pumping, CW lasers are generally used to produce spin polarization. However, high repetition rate pulsed lasers can be superior in producing spin polarization because of high pumping rate. Using the pulsed lasers, we expect to produce spin polarization efficiently for various atomic species which have not yet been spin-polarized. In this study, a tunable pulsed Ti:Sapphire laser operated at 1 kHz was constructed and applied to the optical pumping of Rb atoms with stable nuclei. The efficiency of the spin polarization by the pulsed laser pumping will be reported. [Preview Abstract] |
Saturday, October 11, 2014 3:00PM - 3:15PM |
ML.00005: Development of beta-gamma spectroscopy for precise measurements of beta-decay branching ratios Junya Nagumo The $ft$ values for superallowed beta decays yield the most precise value of $V_{ud}$, the up-down element of CKM matrix. Recently, the $ft$ values for the mirror decays with $T$ = 1/2 can be used to extract precise weak interaction information. In these studies, the precise values of branching ratio as well as $Q_{EC}$ and half -life are required. However, it is very challenging to determine the precise branching ratio for the beta-decay feeding to not only excited states but also the ground state. In this determination, the knowledge of a very precise absolute gamma-ray detection efficiency and the counting system of total number of beta decays are required. Therefore, we developed a new system for beta-gamma spectroscopy with high-energy secondary beam. The high-energy secondary beam including beta emitters was implanted in the center of a 6-mm-thick GSO scintillator. The beta rays were measured by the GSO scintillator, which ensured the high beta-ray detection efficiency of nearly 100\%. The gamma rays were measured by four clover type germanium detectors installed around the GSO scintillator. The absolute gamma-ray detection efficiency was determined by using other superallowed beta emitters with known gamma-ray intensity in the same condition as the nucleus of interest. [Preview Abstract] |
Saturday, October 11, 2014 3:15PM - 3:30PM |
ML.00006: Measurements of Nuclear Recoils in Liquid Argon: Results from SCENE Samuele Sangiorgio The SCENE (SCintillation Efficiency of Noble Element) collaboration has measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase Liquid Argon Time Projection Chamber (LAr-TPC) to a low energy pulsed narrowband neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. The presentation will report recent results including the scintillation and ionization yields for nuclear recoils at varying energies and applied electric fields and the anti-correlation between scintillation and ionization for nuclear recoils. The implications for dark matter experiments will also be discussed. [Preview Abstract] |
Saturday, October 11, 2014 3:30PM - 3:45PM |
ML.00007: Efficient Online and Offline Trigger and Energy Calculation Algorithms for the Nab DAQ Aaron Sprow, Christopher Crawford The Nab experiment requires efficient detection of a low-energy 30 keV proton and a coincident 50-750 keV electron. In addition to the requirements of 2 keV energy precision and a low-threshold trigger, the DAQ must also be capable of 10 ns timing to identify the initial hit of a backscattered electron. We tested six potential DAQ candidates to determine energy and time resolution on a prototype Nab detector mounted in the UCNB apparatus at Los Alamos National Laboratory. In addition to considering the performance of traditional FPGA-implemented FIR's (CR-RC$^{2}$, trapezoid) for event triggering and online energy calculation, we developed and tested a weighted linear least squares fit filter for offline energy reconstruction determined from short, captured waveform traces. In convolving our filter over the length of the trace, we can precisely determine both the energy and time of each event. We present the results of our analysis, and additionally discuss possible filter improvements and implementation into FPGA logic. [Preview Abstract] |
Saturday, October 11, 2014 3:45PM - 4:00PM |
ML.00008: Absolute ionization yield of 6.7 keV argon nuclear recoils in liquid argon Peter Sorensen We have made a first measurement of the total electronic energy loss of low-energy argon atoms stopping in liquid argon. The importance of the measurement is underscored by the fact that state of the art theoretical treatment of this problem is only approximate. While these results are of modest interest to condensed matter theory, they are of keen interest to experiments seeking to directly detect signals due to nuclear recoils. Two particular interactions which would result in nuclear recoil signals are the scattering of hypothetical dark matter particles, or coherent elastic neutrino nucleus scattering. Using quasi mono-energetic neutrons from a collimated and filtered 7Li(p,n) source, we measured the absolute ionization yield of nuclear recoils in liquid argon at 6.7 keV at applied electric fields ranging from 200-2130 V/cm. We will discuss the experimental setup used for these measurements, our findings and their implications, and finally our recent efforts to apply this technique to liquid xenon. [Preview Abstract] |
Saturday, October 11, 2014 4:00PM - 4:15PM |
ML.00009: ABSTRACT WITHDRAWN |
Saturday, October 11, 2014 4:15PM - 4:30PM |
ML.00010: Measuring Flash X-Ray Spectra with a Compton Spectrometer Amanda Gehring, Michelle Espy, Todd Haines, James Hunter, Nick King, Frank Merrill, Robert Sedillo, Algis Urbaitis, Petr Volegov The determination of the x-ray energy spectra of flash radiographic sources is difficult due to the short nature of the pulses ($\sim$ 50 ns). Recently, a Compton spectrometer has been refurbished and investigated as a potential device for conducting these measurements. The spectrometer was originally designed and characterized by Morgan et al [1]. The spectrometer consists of a 300 kg neodymium-iron magnet and measures spectra in the \textless\ 1 MeV to 20 MeV energy range. In this apparatus, the incoming x-rays are collimated into a narrow beam before encountering a converter foil. Compton electrons are ejected and collimated so that the forward-directed electrons enter the magnetic field region of the device. The position of the electrons on the magnet focal plane is a function of their energy, allowing the x-ray spectrum to be reconstructed. Recent energy calibration measurements and the spectrum reconstruction of a Bremsstrahlung source will be presented. \\[4pt] [1] Morgan et al., Nucl. Instr. and Meth. A308 (1991) 544 [Preview Abstract] |
Saturday, October 11, 2014 4:30PM - 4:45PM |
ML.00011: Half-life measurement of $^{7}$Be in materials Tsutomu Ohtsuki The formation of atom-doped C60 and C70 etc. has been investigated by using several types of radionuclides produced by nuclear reactions. From the trace of the radioactivities after high performance liquid chromatography (HPLC), it was found that formation of endohedral fullerenes of Be atom is possible by a recoil process following the nuclear reaction. The decay rate of $^{7}$Be electron capture (EC) was measured in C70 and Be metal with a reference method. The half-lives of $^{7}$Be endohedral C70 and $^{7}$Be in Be metal (Be metal($^{7}$Be)) were found to be 52.45pm0.04 and 53.25pm0.04 days, respectively. This amounts to a 1.5 percent difference in the EC-decay half-life between $^{7}$BeC70 and Be metal($^{7}$Be). The results are a reflection of the different electron wave-functions in nuclear site for $^{7}$Be inside C70 compared to when $^{7}$Be is in a Be metal. The further theoretical interpretation is needed for these experimental results. [Preview Abstract] |
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