Antideuterons as an Indirect Dark Matter Signature: Si(Li) Detector Development and a GAPS Balloon Mission Tsuguo Aramaki Columbia Astrophysics Laboratory
C.J. Hailey (PI), T. Aramaki, J.E. Koglin, N. Madden, K. Mori, H.T. Yu Columbia University
S.E. Boggs University of California, Berkeley
W.W. Craig Lawrence Livermore National Laboratory
H. Fuke, T. Yoshida
Institute of Space & Astronautical Science, Japan Aerospace Exploration Agency F. Gahbauer University of Latvia
R.A. Ong, J. Zweerink University of California, Los Angeles
K.P. Ziock ORNL Oak Ridge National Laboratory Our universe is dominated by Dark Matter and Dark Energy
WMAP measured accurate cosmological information
Galactic Rotation Curve Gravitational Lens What is Dark Matter?
Lots of theories! Supersymmetry
4th generation heavy neutrino Axinos Bino Brane world DM CHAMPS Cryptons D-matter Gravitinos Kaluza-Klein Higgsino Light scalars Minimal DM Mirror particles Neutralino DM Neutralinos - Lightest Supersymmetric Particle (LSP) in SUSY theory New symmetry little Higgs Q-balls - Stable Photino - Interacts with matter very weakly like a heavy neutron Self-interacting DM Simpzillas - Underground experiments measure nuclear recoil SM neutrinos - Underground experiments must be massive – 3rd Sneutrinos Sterile neutrinos generation experiments ~ 1 ton targets SWIMPS - The neutralino is a Majorana particle Theory space little Higgs Wimpzillas - It is its own antiparticle and will co-annihilate Wino There are two different Dark Matter searches
Direct Search Indirect Search Underground detection of nuclear recoils Detect annihilation products
χ N Heat
Ionization q, h,_ W,_ _ e+, γ, ν, p, n , D … χ Scintillation χ
Χ* Experiments - Positron (e+): PAMELA, AMS… ANAIS ELEGANT V LIBRA χχ→W+W-, W+→e+ν ArDM EDELWEISS NAIAD CDMSII EURECA PICASSO - Photon (γ): GLAST, HESS… CUORICINO GEDEON SIMPLE χχ→γγ, χχ→γZ COSME GENIUS SuperCDMS - Neutrino (ν): AMANDA, IceCube… CRESST Genino SuperK Annihilate in the sun, detect upward µ DAMA GERDA WARP _ - Antiproton ( p ) : BESS, AMS, PAMELA DMRC HDMS XENON _ DRIFT IGEX ZEPLIN - Antideuteron (D) : GAPS, AMS
Large scale (~ton) detector is required
Why Antideuterons?
Background free at low energy! GAPS Band = 0.05-0.25 GeV/n -3 10 Primary component: BESS limit Neutralino annihilation 10-4 LZP AMS AMS Other DM models ] LSP GAPS
-1 10-5 LDB LKP eg. Right-Handed Neutrino (LZP)
GeV Secondary Kaluza-Klein Particle (LKP) -1
sr 10-6 Secondary component (Background): -1 s 2 Cosmic_ ray interactions -7 ULDB _ 10 p/ p (CR) +H/He (IS)→ D +…
10-8 - Flux is low, but primary/secondary is large - High sensitivity with balloon
10-9 Signal: Baer & Profumo ’05 - Sensitive to other DM models Donato et al. `08
Antideuteron Flux [m Back: Duperray et al. ‘05 10-10 0.1 1 10 100 Kinetic Energy per Nucleon [GeV/n] GAPS searches unique parameter space complementary to other direct/indirect searches
From Baer & Profumo 2005 100 Direct y t i v i t 10 i s n e
s Both )
G 1 B Z . v e D
( 0.1 I I - S M
D 0.01 C / P χ I S
σ 0.001 GAPS
0.0001 0.001 0.01 0.1 1 10 100 1000 Antideuteron flux / GAPS (ULD balloon) sensitivity
LDB (60days) ULDB (300days) Probe unique regions of parameter space Exploratory
Discovery Detection Concept: Atomic X-rays and Pions _ D Plastic Scintillator TOF Atomic Transitions
Si(Li) Target/Detector Auger e- n ,l Refilling e- o o π- π+
n=nK~15 - 44keV π Exotic Atom _ n=9 D γ n=8 n=7 γ 67keV + π Si n=6 γ
30keV n=2 π+ π- A time of flight (TOF) system tags + candidate events and records velocity π n=1 π- The antiparticle slows down & stops in a + - π Nuclear target material, forming an excited exotic π Annihilation atom with near unity probability - π+ π Deexcitation X-rays provide signature Pions from annihilation provide added X-ray yields were shown to be high background suppression
1. TOF and Depth Sensing Expected Background for 2. Atomic X-rays a 300 Day Flight Type of Expected Basis for 3. Charged Pion Multiplicity Background Events estimate Temporally Scaling from γ- < 0.003 Antiproton/Antideuteron misidentification incoherent X-rays ray telescopes Measured at Temporally 0.001 GAPS-KEK coherent X-rays experiment Monte-Carlo of evaporative & Elastic neutrons 0.002 cascade model, KEK limits 58keV Propagate Secondary- calculated spectra tertiary- 0.006 through atmospheric atmosphere to 67keV antideuterons instrument Data on energy & Nuclear -rays, o γ π branching ratio of shower photons, negligible all possible lines; internal analytic calc.; bremastrahlung GEANT4 sim. GAPS Detector: Si(Li) & Plastic Scintilator
13 layers composed of Si(Li) wafers – Relatively low Z material, 2mm thick – Segmented into 8 strips, ~8cm2 each 3D particle tracking – Timing: ~50 ns – Energy resolution:~2 keV – Proven technology dating from the 1960’s – Dual channel electronics 5-200 keV: X-rays 0.1-200 MeV: charged particle
Si(Li) serves as a target for stopping antideuterons as well as an x-ray detector & particle Tracker
Surrounded by Plastic TOF – Identify incoming charged particles Interesting Feature of GAPS Balloon Experiment 2 - Very large (~4m ) Si(Li) detector, Heat Dissipation & Power Load [W] but simple fabrication dating to Heat Dissipation per Si(Li) channel 0.005 1960’s Solar and other heat 130 - 1st balloon flight of cooled pixellated Total Heat Dissipation 400 Si(Li) detector Power for Si(Li) Detector System 1622 Power for Plastic Detector System 186 - No pressure vessel Other power requirements 200 (allows more mass for target) Total Power 2008 - Very large plastic area (>10m2) with good timing (~ns): TOF Mass Breakdown [kg] ~350kg TOF mass Si(Li) Detectors 204 Si(Li) Electronics, Cables, Support 315 & Cooling Plastic Scintillator 151 PMT, Light-guide, Cables, 190 Electronics, Wrapping Support Gondola, Computers, Telemetry 376 Power, Radiator, Total 1237
Preliminary design estimates are compatible ~200 kg Si(Li) mass with doing good science on a balloon GAPS Detector Development involves commercial prototype evaluation and in-house flight production
- Prototype flight consisting of ~ 10 commercial Si(Li) + TBD number of in-house fabricated Si(Li) - Evaluate thick (4mm) SEMIKON Si(Li), Jan 2009 - Energy resolution - Timing - Detection efficiency - Noise, capacitive cross talk, etc… - Evaluate flight representative thin (2mm) SEMIKON Si(Li), spring 2009 - Parallel development of flight fabrication techniques & facility SEMIKON Si(Li) detector
Structured P+-contact: Boron Ø = 102 mm 4” diameter, 4mm/2mm thick (8 strips) Ø = 94 mm - N+ contact: Lithium (4 mm Guard Ring) - HV - P+ contact: Boron - 8 strips - Guard Ring
2mm thick - Grounded Active Area: 69.4 cm2 Indium ring Detector holder PC board
Si(Li) detector
Indium ring
POM ring Homemade Si(Li) Detector Proven, easy process Structured n+-contact: Li Guard Ring (8 strips) Deep Groove Cut from the ingot
Evaporate Lithium
Produce the deep groove Shallow Well, Au contact and mesa (optional)
4” diameter, 2mm thick Drift the Li into the silicon - N+ contact: Lithium (Al coating) - HV Make strips and guard ring - 8 strips Etch the back (shallow well) - Guard Ring and evaporate Au - P+ contact: Au In-house facility at CU/DTU-NSC - Shallow well - Grounded
Cutting Drifting Etching Si(Li) Characteristic Test
X‐Y stages X‐ray source with collimator - Energy resolution - Dead layer - Dark current - Timing Cold Finger Spacer - Electronics test
Cold Plate Thermal Electric Cooler
Connector to the preamplifier - Pressure: 10-6torr – 1atm
- Temperature: –50°C Spacer - Source: 22Na 55Fe, 109Cd, 133Ba, 241Am A Prototype Flight will provide a Crucial Science & Engineering Demonstration
Balloon Prototype Goals: - Include ~10 commercial (SEMIKON) and a few of our in-house detectors. - Demonstrate stable, low noise operation of the Si(Li) with its polymer coating at float altitude & ambient pressure. - Demonstrate the basic functionality and operation of the TOF system. - Demonstrate the Si(Li) cooling approach & deployable sun shades. Verify thermal model. - Measure incoherent background level in a flight-like configuration.
2011 Prototype flight planned from Hokkaido, Japan GAPS Development Plan Culminates in a Long-Duration Balloon (LDB) Experiment
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Flight Instrument Design Si(Li) Proto Facility Design Facility KEK04 KEK05 Measurements Construction bGAPS Construction Data Analysis & pGAPS Construction Background Studies Antarctic Science Japan Proto-Flight Flight
ORNL
C Hailey (PI), J Koglin, H Yu (PhD thesis ‘08), T Aramaki – Columbia F Gahbauer – U. Latvia/Columbia - modeling T Yoshida & H Fuke – JAXA/ISAS – Gondola systems (BESS Antartica) S Boggs – UC Berkeley – Balloon electronics & background simulation R Ong, J Zweerink – UCLA – TOF, Trigger system & instrument simulations F Christensen – DNSC – Coatings Technology, Si(Li) fabrication N Madden (Columbia), D Landis & Semikon GmBH (T Krings) – Si(Li) and detector electronics K Ziock & L Fabris – ORNL – Electronics & ASIC design
Source of Uncertainty