Cosmic Antihelium Nuclei Sensitivity of the GAPS Experiment

The General Antiparticle Spectrometer (GAPS) is an Antarctic balloon experiment designed for low-energy (0.1$-$0.3 GeV/$n$) cosmic antinuclei as signatures of dark matter annihilation or decay. GAPS is optimized to detect low-energy antideuterons, as well as to provide unprecedented sensitivity to low-energy antiprotons and antihelium nuclei. The novel GAPS antiparticle detection technique, based on the formation, decay, and annihilation of exotic atoms, provides greater identification power for these low-energy antinuclei than previous magnetic spectrometer experiments. This work reports the sensitivity of GAPS to detect antihelium-3 nuclei, based on full instrument simulation, event reconstruction, and realistic atmospheric influence simulations. The report of antihelium nuclei candidate events by AMS-02 has generated considerable interest in antihelium nuclei as probes of dark matter and other beyond the Standard Model theories. GAPS is in a unique position to detect or set upper limits on the cosmic antihelium nuclei flux in an energy range that is essentially free of astrophysical background. In three long-duration balloon flights, GAPS will be sensitive to an antihelium flux on the level of $1.3^{+4.5}_{-1.2}\cdot 10^{-6}\mathrm{m^{-2}sr^{-1}s^{-1}}(\mathrm{GeV}/n)^{-1}$ (95% CL) in the energy range of 0.11$-$0.3 GeV/$n$, opening a new window on rare cosmic physics.Comment: 12 pages, 5 figure

A Patient With Alcoholic Ketoacidosis and Profound Lactemia.

BACKGROUND: Alcoholic ketoacidosis (AKA) is a complex syndrome that results from disrupted metabolism in the setting of excessive alcohol use and poor oral intake. Dehydration, glycogen depletion, high redox state, and release of stress hormones are the primary factors producing the characteristic anion gap metabolic acidosis with an elevated β-hydroxybutyrate (β-OH) and lactate. CASE REPORT: We present the case of a 47-year-old man who presented to the emergency department with metabolic acidosis and profoundly elevated lactate levels who had AKA. He recovered completely with intravenous fluids and parenteral glucose administration. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians should always consider the immediately life-threatening causes of a severe anion gap metabolic acidosis and treat aggressively based on the situation. This case highlights the fact that AKA can present with an impressively elevated lactate levels. Emergency physicians should keep AKA in the differential diagnosis of patients who present with a similar clinical picture

Reconstruction of antinucleus-annihilation events in the GAPS experiment

54siThe General Antiparticle Spectrometer (GAPS) experiment is designed to detect low-energy (< 0.25 GeV/n) cosmic-ray antinuclei as indirect signatures of dark matter. Several beyondthe-standard-model scenarios predict a large antideuteron flux due to dark matter decay or annihilation compared to the astrophysical background. The GAPS experiment will perform such measurements using long-duration balloon flights over Antarctica, beginning in the 2022/23 austral summer. The experimental apparatus consists of ten planes of Si(Li) detectors surrounded by a time-of-flight system made of plastic scintillators. The detection of the primary antinucleus relies on the reconstruction of the annihilation products: the low-energy antinucleus is captured by an atom of the detector material, forming an exotic atom that de-excites by emitting characteristics X-rays. Finally, the antinucleus undergoes nuclear annihilation, producing a “star” of pions and protons emitted from the annihilation vertex. Several algorithms were developed to determine the annihilation vertex position and to reconstruct the topology of the primary and secondary particles. An overview of the event reconstruction techniques and their performances, based on detailed Monte Carlo simulation studies, will be presented in this contribution.openopenT. Aramaki, R. Bird, M. Boezio, S. E. Boggs, V. Bonvicini, D. Campana, W. W. Craig, E. Everson, L. Fabris, H. Fuke, F. Gahbauer, I. Garcia, C. Gerrity, C. J. Hailey, T. Hayashi, C. Kato, A. Kawachi, S. Kobayashi, M. Kozai, A. Lenni, A. Lowell, M. Manghisoni, N. Marcelli, B. Mochizuki, S. A. I. Mognet, K. Munakata, R. Munini, Y. Nakagami, J. Olson, R. A. Ong, G. Osteria, K. Perez, S. Quinn, V. Re, E. Riceputi, B. Roach, F. Rogers, J. A. Ryan, N. Saffold, V. Scotti, Y. Shimizu, M. Sonzogni, R. Sparvoli, A. Stoessl, A. Tiberio, E. Vannuccini, P. von Doetinchem, T. Wada, M. Xiao, M. Yamatani, A. Yoshida, T. Yoshida, G. Zampa, J. ZweerinkAramaki, T.; Bird, R.; Boezio, M.; Boggs, S. E.; Bonvicini, V.; Campana, D.; Craig, W. W.; Everson, E.; Fabris, L.; Fuke, H.; Gahbauer, F.; Garcia, I.; Gerrity, C.; Hailey, C. J.; Hayashi, T.; Kato, C.; Kawachi, A.; Kobayashi, S.; Kozai, M.; Lenni, A.; Lowell, A.; Manghisoni, M.; Marcelli, N.; Mochizuki, B.; Mognet, S. A. I.; Munakata, K.; Munini, R.; Nakagami, Y.; Olson, J.; Ong, R. A.; Osteria, G.; Perez, K.; Quinn, S.; Re, V.; Riceputi, E.; Roach, B.; Rogers, F.; Ryan, J. A.; Saffold, N.; Scotti, V.; Shimizu, Y.; Sonzogni, M.; Sparvoli, R.; Stoessl, A.; Tiberio, A.; Vannuccini, E.; von Doetinchem, P.; Wada, T.; Xiao, M.; Yamatani, M.; Yoshida, A.; Yoshida, T.; Zampa, G.; Zweerink, J

Neural Networks approach to event reconstruction for the GAPS experiment

54siThe General Antiparticle Spectrometer (GAPS) is a balloon-borne experiment, scheduled for a first flight in the austral summer 2022. It is designed to measure low energy (< 0.25 GeV/n) cosmic antinuclei. A particular focus is on antideuterons, which are predicted to have an ultra-low astrophysical background as compared to signals from dark matter annihilation or decay in the Galactic halo. GAPS uses a novel technique for particle identification based on the formation and decay of exotic atoms. To achieve sufficient rejection power for particle identification, an accurate determination of several fundamental quantities is needed. The precise reconstruction of the energy deposition pattern on the primary track is a particularly intricate problem and we developed a strategy devised to solve this using modern machine learning techniques. In the future, this approach can also be used for particle identification. Here, we present preliminary results of these efforts obtained from simulations.openopenT. Aramaki, R. Bird, M. Boezio, S. E. Boggs, V. Bonvicini, D. Campana, W. W. Craig, E. Everson, L. Fabris, H. Fuke, F. Gahbauer, I. Garcia, C. Gerrity, C. J. Hailey, T. Hayashi, C. Kato, A. Kawachi, S. Kobayashi, M. Kozai, A. Lenni, A. Lowell, M. Manghisoni, N. Marcelli, B. Mochizuki, S. A. I. Mognet, K. Munakata, R. Munini, Y. Nakagami, J. Olson, R. A. Ong, G. Osteria, K. Perez, S. Quinn, V. Re, E. Riceputi, B. Roach, F. Rogers, J. A. Ryan, N. Saffold, V. Scotti, Y. Shimizu, M. Sonzogni, R. Sparvoli, A. Stoessl, A. Tiberio, E. Vannuccini, P. von Doetinchem, T. Wada, M. Xiao, M. Yamatani, A. Yoshida, T. Yoshida, G. Zampa, J. ZweerinkAramaki, T.; Bird, R.; Boezio, M.; Boggs, S. E.; Bonvicini, V.; Campana, D.; Craig, W. W.; Everson, E.; Fabris, L.; Fuke, H.; Gahbauer, F.; Garcia, I.; Gerrity, C.; Hailey, C. J.; Hayashi, T.; Kato, C.; Kawachi, A.; Kobayashi, S.; Kozai, M.; Lenni, A.; Lowell, A.; Manghisoni, M.; Marcelli, N.; Mochizuki, B.; Mognet, S. A. I.; Munakata, K.; Munini, R.; Nakagami, Y.; Olson, J.; Ong, R. A.; Osteria, G.; Perez, K.; Quinn, S.; Re, V.; Riceputi, E.; Roach, B.; Rogers, F.; Ryan, J. A.; Saffold, N.; Scotti, V.; Shimizu, Y.; Sonzogni, M.; Sparvoli, R.; Stoessl, A.; Tiberio, A.; Vannuccini, E.; von Doetinchem, P.; Wada, T.; Xiao, M.; Yamatani, M.; Yoshida, A.; Yoshida, T.; Zampa, G.; Zweerink, J

Searching for cosmic antihelium nuclei with the GAPS experiment

At low energies, cosmic antideuterons and antihelium provide an ultra-low background signature of dark matter annihilation, decay, and other beyond the Standard Model phenomena. The General Antiparticle Spectrometer (GAPS) is an Antarctic balloon experiment designed to search for lowenergy (0.1−0.3 GeV/n) antinuclei, and is planned to launch in the austral summer of 2022. While optimized for an antideuteron search, GAPS also has unprecedented capabilites for the detection of low-energy antihelium nuclei, utilizing a novel detection technique based on the formation, decay, and annihilation of exotic atoms. The AMS-02 collaboration has recently reported several antihelium nuclei candidate events, which sets GAPS in a unique position to set constraints on the cosmic antihelium flux in an energy region which is essentially free of astrophysical background. In this contribution, we illustrate the capabilities of GAPS to search for cosmic antihelium-3 utilizing complete instrument simulations, event reconstruction, and the inclusion of atmospheric effects. We show that GAPS is capable of setting unprecedented limits on the cosmic antihelium flux, opening a new window on exotic cosmic physics

Why Do Physicians Vary So Widely in Their Referral Rates?

OBJECTIVE: To determine which physician practice and psychological factors contribute to observed variation in primary care physicians' referral rates. DESIGN: Cross-sectional questionnaire-based survey and analysis of claims database. SETTING: A large managed care organization in the Rochester, NY, metropolitan area. PARTICIPANTS: Internists and family physicians. MEASUREMENTS AND MAIN RESULTS: Patient referral status (referred or not) was derived from the 1995 claims database of the managed care organization. The claims data were also used to generate a predicted risk of referral based on patient age, gender, and case mix. A physician survey completed by a sample of 182 of the physicians (66% of those eligible) included items on their practice and validated psychological scales on anxiety from uncertainty, risk aversiveness, fear of malpractice, satisfaction with practice, autonomous and controlled motivation for referrals and test ordering, and psycho-social beliefs. The relation between the risk of referral and the physician practice and psychological factors was examined using logistic regression. After adjustment for predicted risk of referral (case mix), patients were more likely to be referred if their physician was female, had more years in practice, was an internist, and used a narrower range of diagnoses (a higher Herfindahl index, also derived from the claims data). Of the psychological factors, only greater psychosocial orientation and malpractice fear was associated with greater likelihood of referral. When the physician practice factors were excluded from the analysis, risk aversion was positively associated with referral likelihood. CONCLUSIONS: Most of the explainable variation in referral likelihood was accounted for by patient and physician practice factors like case mix, physician gender, years in practice, specialty, and the Herfindahl index. Relatively little variation was explained by any of the examined physician psychological factors

The GAPS Instrument: A Large Area Time of Flight and High Resolution Exotic Atom Spectrometer for Cosmic Antinuclei

54siLow-energy cosmic ray antideuterons (< 0.25 GeV/) are a compelling, mostly uncharted channel of many viable dark matter models and benefit from highly suppressed astrophysical background. The General Antiparticle Spectrometer (GAPS) is a first-of-its-kind exotic-atom-based Antarctic balloon-borne experiment specialized for detection of low-energy antiprotons, antideuterons, and antihelium with a targeted launch in 2022. The results of novel technology development and a summary of current construction status are the focus of this contribution. GAPS exploits a novel antiparticle identification technique based on exotic atom formation and decay, allowing more active target material for a larger overall acceptance since no magnet is required. The GAPS instrument consists of a large-area (∼ 50 m2) scintillator time-of-flight, ten planes of custom silicon detectors with dedicated ASIC readout, and a novel oscillating heat pipe cooling approach. This contribution will briefly introduce the exotic atom detection technique. Following this, the instrument design will be discussed and detailed description of experimental hardware and expected performance will be presented. I will conclude with recent construction and testing progress while also highlighting developments of a scaled, integrated prototype.noneopenT. Aramaki, R. Bird, M. Boezio, S. E. Boggs, V. Bonvicini, D. Campana, W. W. Craig, E. Everson, L. Fabris, H. Fuke, F. Gahbauer, I. Garcia, C. Gerrity, C. J. Hailey, T. Hayashi, C. Kato, A. Kawachi, S. Kobayashi, M. Kozai, A. Lenni, A. Lowell, M. Manghisoni, N. Marcelli, B. Mochizuki, S. A. I. Mognet, K. Munakata, R. Munini, Y. Nakagami, J. Olson, R. A. Ong, G. Osteria, K. Perez, S. Quinn, V. Re, E. Riceputi, B. Roach, F. Rogers, J. A. Ryan, N. Saffold, V. Scotti, Y. Shimizu, M. Sonzogni, R. Sparvoli, A. Stoessl, A. Tiberio, E. Vannuccini, P. von Doetinchem, T. Wada, M. Xiao, M. Yamatani, A. Yoshida, T. Yoshida, G. Zampa, J. ZweerinkAramaki, T.; Bird, R.; Boezio, M.; Boggs, S. E.; Bonvicini, V.; Campana, D.; Craig, W. W.; Everson, E.; Fabris, L.; Fuke, H.; Gahbauer, F.; Garcia, I.; Gerrity, C.; Hailey, C. J.; Hayashi, T.; Kato, C.; Kawachi, A.; Kobayashi, S.; Kozai, M.; Lenni, A.; Lowell, A.; Manghisoni, M.; Marcelli, N.; Mochizuki, B.; Mognet, S. A. I.; Munakata, K.; Munini, R.; Nakagami, Y.; Olson, J.; Ong, R. A.; Osteria, G.; Perez, K.; Quinn, S.; Re, V.; Riceputi, E.; Roach, B.; Rogers, F.; Ryan, J. A.; Saffold, N.; Scotti, V.; Shimizu, Y.; Sonzogni, M.; Sparvoli, R.; Stoessl, A.; Tiberio, A.; Vannuccini, E.; von Doetinchem, P.; Wada, T.; Xiao, M.; Yamatani, M.; Yoshida, A.; Yoshida, T.; Zampa, G.; Zweerink, J