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Primary component:  neutralino annihilation __

Antideuterons as an Indirect Dark Matter Signature: Design and Preparation for a Balloon-born GAPS Experiment. Primary component:  neutralino annihilation __ X+X → D + … Secondary component:  spallation

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Primary component:  neutralino annihilation __

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  1. Antideuterons as an Indirect Dark Matter Signature: Design and Preparation for a Balloon-born GAPS Experiment

  2. Primary component:  neutralino annihilation __ X+X → D + … Secondary component: spallation __ p+H → p+H+D+… __ p+He → p+He+D+… GAPS is essentially a background free experiment GAPS represents a major improvement over the state of the art GAPS has outstanding discovery potential for a variety of DM models Low-energy, neutralino-neutralino producedantideuterons are near background free & accessible by GAPS BESS limit LZP (m = 40 GeV) LSP (m = 100 GeV) GAPS LKP (m = 500 GeV) LDB Secondary/Tertiary ULDB Significant antideuteron flux at the earth (with propagation & solar modulation) first pointed out by Donato et al. 2000 10-3 10-4 10-5 10-6 Antideuteron Flux [m2 s-1 sr-1 GeV-1] 10-7 10-8 10-9 Signal: Baer & Profumo ’05 Back: Duperray et al. ‘05 10-10 0.1 1 10 100 Kinetic Energy per Nucleon [GeV/n]

  3. SUSY discovery potential for an antideuteron experiment is similar to direct detection methods LDB ULDB Exploratory Discovery From Baer & Profumo 2005 There are over 20 current or planned direct detection experiments to probe SUSY DM A balloon GAPS antideuteron search offers SUSY parameter space complementarity to direct detection, underground searches GAPS probes an unique region of parameter space inaccessible by other methods Direct Both GAPS

  4. _ D GAPS is based on radiative emission ofantiparticles captured into exotic atoms p* Atomic Transitions no,lo n=nK~15 n=6 g n=5 g n=4 g n=3 n=2 p+ n=1 p+ p- p- po Plastic Scintillator TOF Si(Li) Target/Detector Auger e- Refilling e- p* 44 keV LadderDeexcitations Dn=1, Dl=1 p* 30 keV p* A time of flight (TOF) system tags candidate events and records velocity Nuclear Annihilation The antiparticle slows down & stops in a target material, forming an excited exotic atom with near unity probability Antiprotonic yields measured at KEK in 2004 & 2005 in various targets. Deexcitation X-rays provide signature Pions from annihilation provide added background suppression

  5. Si(Li) Wafers will be hexagonally packed into detector planes & surrounded by segmented Plastic TOF ~200 kg Si(Li) mass – Similar to direct detection target mass

  6. GAPS employs three techniques to uniquely identify antideuterons with enormous background suppression Expected Background for a 300 Day Flight 1. Atomic X-rays 2. TOF and Depth Sensing 3. Charged Pion Multiplicity Exploratory

  7. Si(Li) Serves a Target for Stopping Antideuterons as well as an X-ray Detector & Particle Tracker • Modular approach for ease of in-field assembly • Relatively low Z provides: good compromise between X-ray escape and detection Low internal background. • Excellent timing (50 ns) & energy resolution (2 keV – much better than NaI, but modest for Si)  2 X-ray coincidence sufficient (previous designs used 3 X-rays) • Relatively course pixels (8 cm2)  Keeps channel count low but still provides for low pileup. • Dual channel electronics (5-200 keV & 0.1-200 MeV) Good charged particle tracking • Proven technology dating to 60’s • We have tested a prototype detector that exceeds our requirements Challenge is in large-scale fabrication

  8. A Prototype Flight will Provide a Crucial Science & Engineering Demonstration Balloon Prototype Goals: • Demonstrate stable, low noise operation of the Si(Li) with its polymer coating at float altitude & ambient pressure. • Demonstrate the Si(Li) cooling approach & deployable sun shades. Verify thermal model. • Measure incoherent background level in a flight-like configuration. 2009 Flight planned from Japan with ISIS/JAXA participation

  9. GAPS Development Plan Culminates in a Long-Duration Balloon (LDB) Experiment 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Flight Instrument Design Facility Construction Facility Design Si(Li) Proto Measurements bGAPS Construction KEK04 KEK05 pGAPS Construction Data Analysis & Background Studies JapanProto-Flight Antarctic Science Flight • Flight proposal submitted to NASA in Spring 2007 • Flight of GAPS prototype from Japan in 2009 • LDB GAPS flight from Antarctica in 2013 • Experiment design will be ultra long duration (ULDB) capable to exploit such a launch if it becomes available; flight duration >100 days • Growing collaboration & adding expertise to execute this plan NASA/ULDB

  10. Primary GAPS Science Goals Antideuteron Dark Matter (DM) Signature Low-Energy Antiproton Spectroscopy Primordial Black Holes From Barrau et al. 2003 From Baer & Profumo 2005 • Measure antideuterons from evaporating PBH’s • Potentially constrain inflation temperature • Measure 104-105 antiprotons <0.3 GeV (BESS-polar measured 26 @ <0.3 GeV) • Perform both DM and cosmic-ray physics • Execute deep searches for SUSY & UED DM • Complementary with direct and other indirect measurements

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