Bulletin of the American Physical Society
2014 Annual Meeting of the Far West Section of the APS
Volume 59, Number 14
Friday–Saturday, October 24–25, 2014; Reno, Nevada
Session H3: High Energy/Accelerator Physics |
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Chair: Matt Thompson, Tri Alpha Energy Room: JCSU 422 |
Saturday, October 25, 2014 2:00PM - 2:12PM |
H3.00001: A Synchrotron Radiation Research Facility for Africa Herman Winick Africa is the only habitable continent without a synchrotron light source. Dozens of African scientists use facilities abroad. Although South Africa has become a member of ESRF. the number of users is limited by distance and travel cost. A light source in Africa would give thousands of African scientists access to this tool. Momentum is now building for an African light source, as a collaboration involving several sub-Saharan African countries. An interim Steering Committee has been formed. SESAME, now nearing completion in Jordan as a collaboration of 9 countries in the Middle East (www.sesame.org.jo) may be the example followed. UNESCO became the umbrella organization for SESAME at its Executive Board 164th session, May 2002, as it did in the case of CERN in the 1950s. UNESCO's Executive Board described SESAME as ``a quintessential UNESCO project combining capacity building with vital peace-building through science'' and ``a model project for other regions.'' It is likely that UNESCO, if asked, would play a similar role as a facilitator for an African light source. [Preview Abstract] |
Saturday, October 25, 2014 2:12PM - 2:24PM |
H3.00002: mono-Z': The discovery potential in a search for dark matter in events with a Z' boson and missing transverse energy Kevin Bauer, Marcelo Autran, Tongyan Lin, Daniel Whiteson We analyze the LHC's potential for dark matter discovery in ATLAS events with missing transverse energy and a Z' decaying to a pair of jets or leptons. Many dark matter searches are ongoing at the LHC, analyzing events with missing transverse energy. However, a final state of Z' and missing energy has not yet been studied and contains significant discovery potential. Examples of effective field theory models for Z' production with dark matter are introduced. Using simulations of the 8 TeV LHC run, we explore reconstruction and selection strategies and discuss our sensitivity by comparing our expected limits to existing theory parameter limits. [Preview Abstract] |
Saturday, October 25, 2014 2:24PM - 2:36PM |
H3.00003: A Cryogenic Piezoelectric Rotary Drive System for the Axion Dark Matter Experiment Kelly Backes, Bella Urdinaran The nature of Dark Matter is a central mystery in physics and one candidate particle is the axion. Axions can be detected by their conversion to microwave photons in a cryogenically cooled resonant cavity immersed in a magnetic field. The microwave cavity's resonant frequency must be tuned to match the axion's mass, which is currently an unknown parameter. This frequency can be changed by rotating tuning rods inside of the cavity. Currently a system of stepper motors and gear boxes is used to tune these rods, but the gear boxes add too much heat. The experiment needs to run as cold as possible to minimize the background noise from blackbody radiation. A rotary drive system based on piezoelectric's should generate much less heat. Commercial piezo systems are expensive and have low torque so we are using more inexpensive design that should give higher torque. The behavior of this piezoelectric system will be discussed. [Preview Abstract] |
Saturday, October 25, 2014 2:36PM - 2:48PM |
H3.00004: Updates from the ADMX-HF Experiment Timothy Shokair The Axion Dark Matter eXperiment - High Frequency (ADMX-HF) is a a collaboration of JILA/Colorado, LLNL, UC Berkeley, and Yale to search for dark matter axions in the 4-10 GHz (20-100 $\mu$ev) range. The method is to convert axions into photons via the Primakoff effect in a cylindrical microwave cavity immersed in an ultra-cold 9T magnet. In addition to probing a new mass range of axions, ADMX-HF will serve as a test-bed for new concepts in microwave cavity axion detection. Concepts include hybrid superconducting cavities and operation in squeezed-state modes to reduce amplifier noise. The experiment is currently in the commissioning phase, and is expected to be in full data-taking mode by the end of 2014. [Preview Abstract] |
Saturday, October 25, 2014 2:48PM - 3:00PM |
H3.00005: The time-dependent non-Abelian Aharonov-Bohm effect Max Bright, Douglas Singleton In this talk I discuss the time-dependent Aharonov-Bohm effect for non-Abelian gauge fields. We use the well known Coleman plane wave solutions to the time-dependent Yang-Mills field equations to investigate the non-Abelian Aharonov-Bohm phase shift. For this solution, we find a cancellation between the phase shift coming from the non-Abelian ``magnetic'' field and the phase shift coming from the non-Abelian ``electric'' field, which inevitably arises in time-dependent cases. We compare these results to the results for the Abelian time-dependent Aharonov-Bohm effect. [Preview Abstract] |
Saturday, October 25, 2014 3:00PM - 3:12PM |
H3.00006: Investigation of Self Triggered Cosmic Ray Detectors using Silicon Photomultiplier Adriaan Knox, Rommel Niduaza The inexpensive silicon photomultiplier (SiPM) is a highly sensitive light detector capable of measuring single photons. Since it operates slightly above the breakdown voltage it also exhibits high dark count rates. We describe our investigation of SiPM, the multi-pixel photon counters (MPPC) made by Hamamatsu, as readout detectors for plastic scintillators. We discuss the results of using MPPC scintillation detectors in self triggered mode for detecting cosmic ray particles. Plastic scintillator sheets embedded with blue to green wavelength shifting fibers were optically coupled to the MPPC which detected the scintillation light. Amplified MPPC signals were fed to discriminators, whose output pulse widths were set to 25nsec to minimize random coincidences, and the threshold for passing signal amplitudes was adjusted accordingly to give a reasonable coincidence count rate. Moreover, the detector waveforms were digitized using a 5 Giga sample/second waveform digitizer, the DRS4, and triggered with the coincidence logic to capture the MPPC waveforms. Offline analysis of the digitized waveforms was accomplished using the CERN package PAW. The results of our analysis and its application in a 4 detector cosmic ray array would also be discussed. [Preview Abstract] |
Saturday, October 25, 2014 3:12PM - 3:24PM |
H3.00007: Investigation of the Effect of Temperature on Silicon Photomultplier for Cosmic Ray Detectors Daniel Ruiz Castruita, Fatima Ramirez, Stefan Ritt The silicon photomultiplier (SiPM) is an extremely sensitive light detector capable of measuring very dim light and single photons. Its high gain comes from operating at slightly above the breakdown voltage, which is also accompanied by high dark count rate. At this conference, we describe our investigation of using SiPM, the multipixel photon counters (MPPC) from Hamamatsu, as possible readout detectors in a cosmic ray scintillating detector array. Our investigation, includes implementation of a novel design that automatically adjusts for the bias voltage to the MPPC detectors to compensate for changes in the ambient temperature. We present results in using short pulses as test input waveforms for unity gain amplifiers (TI LMH6559) constructed to maintain the detector signal integrity over long length of cable. Furthermore, we describe our investigations for the MPPC detector characteristics at different bias voltages and temperatures. Our experimental setup consists of a 5 Giga sample/second waveform digitizer, the DRS4, triggered to capture the MPPC detector waveforms, in coincidence with a cosmic ray telescope. Analysis of the digitized waveforms, accomplished using the CERN package PAW, would be presented. [Preview Abstract] |
Saturday, October 25, 2014 3:24PM - 3:36PM |
H3.00008: Implementing Xbee Wireless Network to Monitor Cosmic Ray Detectors Rommel Niduaza The silicon photomultiplier (SiPM) is a highly sensitive light detector capable of measuring very dim light and single photons. It is biased slightly above the breakdown voltage, which results in high gain that is also very sensitive to changes in temperature. At this conference, we describe our experiments in using the popular Xbee wireless transceivers as possible communication devices to remotely monitor the changes in temperature for the SiPM from Hamamatsu. The Xbee modules are paced in a mesh network and communicate from a distance to monitor the resistance from platinum temperature sensors, to be incorporated with the SiPM detectors. Our investigations include extensive evaluation of the Xbee units for readout of the platinum sensor voltages for digitizing the senor signals using the Xbee's onboard 10bit ADC. We have successfully implemented a mesh network consisting of 4 Xbee modules placed at indoor settings and have tested the network communications for maximum range between 2 Xbee modules at outdoor settings as well. Moreover, we describe our data acquisition setup using a Raspberry Pi computer and custom made programs to analyze and receive the sensor data communicated between Xbee modules. [Preview Abstract] |
Saturday, October 25, 2014 3:36PM - 3:48PM |
H3.00009: Antimatter May be a Form of Dark Matter Walton Perkins Two observed properties of dark matter are that it does not emit light (that we can detect) and it does not reflect ordinary light. A comparison of the elementary and composite photon theories shows that they are very similar with each theory having advantages in some areas. The major difference is that in the composite theory the antiphoton is different than the photon. While the composite photon is formed of a left-handed electron neutrino and a right-handed electron antineutrino, the antiphoton is formed of a right-handed electron neutrino and a left-handed electron antineutrino. The neutrino and antineutrino of the antiphoton have the wrong helicity to interact with ordinary matter because the weak interaction is V -- A. The only interaction of such neutrinos with matter would be through gravity. In a symmetric manner the neutrino and antineutrino of the photon have the wrong helicity to interact with antimatter where the weak interaction is V $+$ A. Thus, we could not detect light from antimatter galaxies, and ordinary photons would pass through antimatter galaxies without interaction. These predictions of the composite photon theory will be tested in the upcoming ALPHA and ASACUSA antihydrogen experiments. The matter-antimatter asymmetry puzzle could be solved if the universe contains an equal amount of matter and antimatter. Antimatter galaxies may not have been observed because their antiphotons are not detectable. However, the presence of antimatter equal to matter in the universe cannot explain all the observed effects of dark matter. [Preview Abstract] |
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