Bulletin of the American Physical Society
APS April Meeting 2012
Volume 57, Number 3
Saturday–Tuesday, March 31–April 3 2012; Atlanta, Georgia
Session B10: Non-accelerator Neutrino Experiments |
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Sponsoring Units: DPF Chair: Yuri Efremenko, University of Tennessee Room: Embassy A |
Saturday, March 31, 2012 10:45AM - 10:57AM |
B10.00001: SNO+ Readout Electronics Upgrades Richard Bonventre, Timothy Shokair, Robert Knapik The SNO+ experiment is designed to explore several topics in neutrino physics including neutrinoless double beta decay, reactor antineutrinos, and low energy solar neutrinos. SNO+ uses the existing Sudbury Neutrino Observatory (SNO) detector, with the heavy water target replaced with liquid scintillator. The new target requires an upgrade to the command and control electronics to handle the higher rates expected with scintillation light as compared to Cherenkov light. The readout electronics have been upgraded to autonomously push data to a central data acquisition computer over ethernet from each of the 19 front end crates. The autonomous readout is achieved with a field programmable gate array (FPGA) with an embedded processor. Inside the FPGA fabric a state machine is configured to pull data across the VME-like bus of each crate. A small C program, making use of the open source Light Weight IP (LWIP) libraries, is run directly on the hardware (with no operating system) to push the data via TCP/IP. The hybrid combination of `high-level' C code and a `low-level' VHDL state machine is a cost effective and flexible solution for reading out individual front end crates. [Preview Abstract] |
Saturday, March 31, 2012 10:57AM - 11:09AM |
B10.00002: Trigger System Upgrades for the SNO+ Experiment Andrew Mastbaum The SNO+ experiment, which will study neutrino-less double beta decay, low-energy solar neutrinos, antineutrinos from reactors and natural sources, nucleon decay, and possibly supernova neutrinos, inherits its detector infrastructure from the SNO experiment. To accomplish its physics goals, SNO+ will use scintillation light in liquid LAB, in contrast to SNO's Cherenkov radiation in D$_{2}$O, resulting in a significantly higher light yield. To cope with this increase, readout and analog trigger electronics required redesign. The new analog trigger, in addition to handling higher-current signals, adds programmable logic which will capture below-threshold secondary decays, providing a coincidence tag for some important backgrounds. We present an overview of the experiment and a discussion of the new trigger electronics and their benefits. [Preview Abstract] |
Saturday, March 31, 2012 11:09AM - 11:21AM |
B10.00003: Environmental Effects on TPB Films Christie Chiu The future neutrino detector MicroBooNE at Fermilab will rely on liquid argon scintillation of wavelength 128 nm for the trigger, as well as for determining the time and location of neutrino events. To better detect this light, we use Tetraphenyl Butadiene (TPB) embedded in polystyrene which shifts the light to a peak wavelength of 425 nm. Although we would like to store TPB films for several weeks at a time, we observed that they degraded significantly after only one day. We examined environmental effects on TPB degradation by tracking the performance of several plates placed in different conditions with varying light exposure and humidity levels. We also looked at the ability of desiccation to restore TPB films. This talk presents the study of the degradation between plates kept in each condition and discusses the effectiveness of desiccation to restore the films. [Preview Abstract] |
Saturday, March 31, 2012 11:21AM - 11:33AM |
B10.00004: Tests of Magnetic Shielding of MicroBooNE Photomultiplier Tubes at Cryogenic Temperatures: Demonstration of Efficacy Evan Shockley, Timothy McDonald, Paul Nienaber The MicroBooNE detector, a liquid argon time projection chamber (LArTPC) positioned in the Booster Neutrino Beam (BNB) line at Fermilab and used to detect charged particles produced by interactions of those neutrinos, employs photomultiplier tubes (PMTs) to detect scintillation light used in certain triggering modes. Magnetic fields, even those as small as those from the Earth, can adversely affect tube performance, particularly that of the large (eight-inch diameter) tubes used in MicroBooNE. The location of the PMTs inside the liquid argon cryostat poses the additional challenge of shielding within a cryogenic environment. This presentation details procedures developed and carried out using a cryogenic test stand at Fermilab. Results from these tests demonstrate the effectiveness of shields manufactured from a cryogenic magnetic material in greatly reducing the impact of geomagnetic fields on PMT operation. [Preview Abstract] |
Saturday, March 31, 2012 11:33AM - 11:45AM |
B10.00005: EXO--200 Muon Veto System David Auty EXO200 is searching for neutrinoless double beta decay of $^{136}$Xe. This is process has not been observed and only occurs if the neutrino has a Majorana mass. If $^{136}$Xe decays via neutrinoless double beta decay it has a half life of $<$10$^{23}$yr. For such a low rate backgrounds need to be kept to a minimum. One source of backgrounds is cosmic-ray muons. Muons need to be vetoed with a efficiency of $>$90\% for EXO--200 to achieve it's desired sensitivity. I will to talk about the commissioning of the veto system and it's performance as part of the EXO--200 cosmic ray veto. [Preview Abstract] |
Saturday, March 31, 2012 11:45AM - 11:57AM |
B10.00006: Status of the EXO-200 double beta decay search Ryan MacLellan A 200\,kg low-background liquid Xe double beta decay detector (EXO--200) has been installed underground at the WIPP facility outside Carlsbad, NM. EXO--200 has already provided the first measurement of the two-neutrino decay mode of $^{136}$Xe with a half-life of $2.11\pm0.04$(stat.)$\pm0.21$(syst.)$\times10^{21}$\,yr. While two neutrino double beta decay has already been observed by other experiments, this is the first observation using $^{136}$Xe and also the rarest. I will provide an update on the status of our experiment and the search for neutrinoless double beta decay. [Preview Abstract] |
Saturday, March 31, 2012 11:57AM - 12:09PM |
B10.00007: Directed Neutrino Beam with Electron Capture Beta Decay Vladimir Tsifrinovich, Lorcan Folan, Christina DeAngelis We suggest generation of directed neutrino beams using electron capture beta decay sources. The basic idea is the following. Consider a Gamov-Teller transition with a decrease of nuclear spin I of one unit: $I\to I-1$. Assume that the nuclear spins are highly polarized by a magnetic field at low temperature. In this case the z-component of the total angular momentum before decay is $F_z =I$. The electron capture beta decay produces an unpaired electron with spin $S=\frac{1}{2}$ and a neutrino with spin $V=\frac{1}{2}$. From conservation of the z-component of the angular momentum we obtain after the decay $I_z =I-1, S_z =\frac{1}{2}, V_z =\frac{1}{1}.$ From the helicity requirement, the emitted neutrino momentum is opposite to the direction of its spin. Thus, the considered source generates a directed neutrino beam propagating in the negative z-direction. We show an opportunity for experimental detection of the average recoil force produced by the neutrino emission with a conventional technique of atomic force microscopy. [Preview Abstract] |
Saturday, March 31, 2012 12:09PM - 12:21PM |
B10.00008: Double Chooz Neutron Detection Efficiency with Calibration System Pi-Jung Chang The Double Chooz experiment is designed to search for a non-vanishing mixing angle theta13 with unprecedented sensitivity. The first results obtained with the far detector only indicate a non-zero value of theta13. The Double Chooz detector system consists of a main detector, an outer veto system and a number of calibration systems. The main detector consists of a series of concentric cylinders. The target vessel, a liquid scintillator loaded with 0.1{\%} Gd, is surrounded by the gamma-catcher, a non-loaded liquid scintillator. A buffer region of non-scintillating liquid surrounds the gamma-catcher and serves to decrease the level of accidental background. There is the Inner Veto region outside the buffer. The experiment is calibrated with light sources, radioactive point sources, cosmics and natural radioactivity. The radio-isotopes sealed in miniature capsules are deployed in the target and the gamma-catcher. Neutron detection efficiency is one of the major systematic components in the measurement of anti-neutrino disappearance. An untagged 252Cf source was used to determine fractions of neutron captures on Gd, neutron capture time systematic and neutron delayed energy systematic. The details will be explained in the talk. [Preview Abstract] |
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