Future balloon experiments for the measurement of electron spectra at high energy P. S. Marrocchesi Univ. di Siena INFN-Pisa Gruppo Collegato di Siena RICAP09 – Rome – May 13-15 2009
Outline of the talk � Physics goals � Magnetic spectrometer: - PEBS � Calorimetric experiment: ~ 30 m - CALET-POLAR � Electron Synchrotron experiment: - CREST
3 PEBS - Positron Electron Balloon Spectrometer RWTH Aachen Stefan Schael
PEBS (Positron Electron Balloon Spectrometer) • A dedicated balloon experiment to provide a competitive measurement of the cosmic ray positron flux. • The spectrometer is based on a scintillating fiber tracker with SiPM readout. • proton rejection achieved by a combination of ToF, TRD, ECAL and Tracker. • R&D Phase: 2006 - 2009 • PEBS-1 with permanent magnet (First Flight: Summer 2012 from Kiruna, Sweden) • PEBS-2 with superconducting coil (proposed for an Antarctic flight in 2014) 4 4
PEBS-1 Experiment Focused on the measurement of the positron fraction below 20 GeV permanent magnet
6 PEBS-1: +/- separation up to 20 GeV
PEBS-1 Permanent Magnet Weight 250 kg, B-Field = 0.34 Tesla , R Inner = 0.31 m, R outer = 0.43 m, Height = 12.5 cm 7
PEBS-1 Experiment 2012 / 2013 Spectrometer: ± separation up to 20 GeV σ p p = 0.011 ⋅ p ⊕ 0.07 Fiber tracker: 250 μ m closely packed fibers readout by SiPM array 8
TRD TRD μ m of straw modules and 10 μ � 2 x 8 layer 2 x 8 layer of straw modules and 10 m � fiber fleece radiator. fleece radiator. fiber � TR x TR x- -ray photons absorbed by Xe/CO ray photons absorbed by Xe/CO 2 � 2 mixture (80:20) in 6 mm straw tubes mixture (80:20) in 6 mm straw tubes μ m tungsten wire with 30 μ with 30 m tungsten wire � Proportional mode with a gas Proportional mode with a gas- -gain of gain of � 3000. 3000. � The signals are readout by VA chips. The signals are readout by VA chips. � � SAME DESI GN AS THE AMS SAME DESI GN AS THE AMS- -02 TRD 02 TRD � � Detection possible with Lorentz boosts > 300. � Discriminate e+ (TR) against p (no TR)
10 Launch Sides for PEBS-1: Kiruna => Alaska
11 Geomagnetic- Geomagnetic- Cutoff Cutoff
Skycoverage of PEBS 12 Skycoverage of AMS-2
PEBS-2 Experiment 2014 / 2015 13
PEBS-2 • A dedicated balloon experiment to provide a competitive measurement of the cosmic ray positron flux up to 2 TeV. • The spectrometer is based on a scintillating fiber tracker with SiPM readout in a superconducting magnet with BL 2 = 0.8Tm 2 . The proton rejection of ~10 6 can be achieved by a • combination of ToF, TRD, ECAL and Tracker. • Key parameters: ~3000 cm 2 sr Acceptance: Weight: ~2000 kg Power: ~900 Watt • R&D Phase: 2006 - 2009 • Construction Phase: 2010 - 2012 • First Flight (from McMurdo): December 2014 ? 14 14
σ p p = 1.8 ⋅ 10 − 4 ⋅ p ⊕ 0.008 -2 15
PEBS
PEBS
Positron fraction up to 2 TeV Stefan Schael 18 RWTH Aachen
positron & electron fluxes up to 2 TeV 19 Stefan Schael 19 RWTH Aachen
PEBS Collaboration Proposal for PEBS-1 & PEBS-2 submitted to NASA in March 2009 by: Prof. J. Beatty, Ohiho State University, USA ToF, Gondola • • Prof. G. Dissertori, ETH Zuerich, Switzerland ECAL • Prof. Dr. T. Nakada, EPF Lausanne, Switzerland ECAL • Prof. Dr. S. Schael, RWTH Aachen, Germany Magnet, TRD, Tracker Co-PI for PEBS • Prof. Dr. S. Swordy, University Chicago, USA RICH, ToF Co-PI for PEBS 20
CALET - POLAR • Balloon flights of the CALET collaboration • Collaboration with Japanese National Ballooning (ISAS
Japanese Experiment Module:KIBO Exposed Facility (EF) CALET
CALET on a balloon • bCALET-1 (1/64 scale of CALET ） – was flown in 2006 from Sanriku balloon center Technical flights: • bCALET-2 (1/16 scale of CALET) Prototype tests – in preparation – approved for short (test) flight in the Summer 2009 from Japan • bCALET-3 Technical flight: (1/4 scale of CALET) System tests – approved for test flight in 2010 from Brazil or Australia • CALET-POLAR Science LDB flight – proposed for Long Duration Flight in 2011 from Svalbard
CALET- POLAR concept 72º Silicon Array - SIA Imaging Calorimeter IMC(2 X o ) W/SciFi calorimeter WCAL (24 X o ) Neutron detector NEUCAL LOW ASPECT-RATIO → LARGE GF GF ~ 7300 cm 2 sr total of 26 X o • inclusive electrons + positrons BELOW 1 TeV: investigate ATIC structure with NO Carbon target mm Kg W 2 sr) GF (cm Relative GF X 0 50 170 SIA 810 x 810 x 50 366 x Pamela 20 16.3 70 84 IMC 640 x 640 x 60 15 x AMS-02 500 15.0 450 162 WCAL 500 x 500 x 120 2.9 x PEBS 2500 14.3 168 50 NEUCAL 680 x 680 x 100 1500 1.5 + 18 4.9 x ATIC Trig+DAQ 35 3.2 x ECAL 2300 5 + 18 TOT 738 501
Full containment of the electromagnetic shower in 26 X o WCAL IMC electron electron
Large longitudinal leakage of the hadronic shower in 26 X o WCAL IMC proton proton
Example of early interacting proton generating an “electron-like” shower neutrons WCAL IMC
SciFi Belts Detector Development Detector Development MAPMT Lower half of the Silicon Array (SIA) FEC Pair of Si sensors (64 pixels each) developed in Italy for the SIA - - - SciFi Belt 64-anode PMT BGO FEC ( VA32, TA, 16bits ADC, FPGA)
Japanese Experiment Module: KIBO CALET on the ISS - 2013 Exposed Facility Svalbard CALET-POLAR balloon flight - 2011 Nobile/Amundsen Stratospheric Balloon Center - Svalbard
2006 LAUNCH - 17 DAYS – PEGASO (Italian Space Agency - ASI) COMPLETE CIRCUMPOLAR TRAJECTORY
Detect synchrotron radiation of primary electron as it passes through � Earth’s magnetic field Advantage: Effective area of instrument greatly increased. � � Area determined by R S , not physical size. Antarctic long duration balloon flights � Large proton Large proton rejection rejection Long Long exposure time exposure time the CREST collaboration: Penn State Univ. Indiana Univ. Univ. of Chicago Northern Kentucky Univ. Large Large Univ. of Michigan acceptance acceptance 31
� Signal: Signal: Electron events appear as a Electron events appear as a line of photons arriving line of photons arriving � nearly simultaneously; ; nearly simultaneously CREST will extend the TeV electron flux measurements from ~2 TeV to CREST will extend the � � ~ 50 TeV (depending on length of flight); (depending on length of flight); � Mean photon energy related to primary electron energy: Mean photon energy related to primary electron energy: � ε = 12 keV for 2.5 TeV electron; 5 MeV for 50 TeV electron; ε = 12 keV for 2.5 TeV electron; 5 MeV for 50 TeV electron; � Strong atmospheric absorption below ~30 keV; Strong atmospheric absorption below ~30 keV; � � Backgrounds: Backgrounds: � � Random singles coincidences (cosmic and CR shower x Random singles coincidences (cosmic and CR shower x- -ray photons ray photons � and large charged particle flux); and large charged particle flux); � Interactions in the detector and frame; Interactions in the detector and frame; � π , efficient discrimination against charged particles. Requires 4 π � Requires 4 , efficient discrimination against charged particles. � 32
Energy distribution of Energy distribution of Surviving synchrotron photons at Surviving synchrotron photons at START at (0,0) START at (0,0) surviving photons surviving photons ° S & 135 ° E 75 ° S & 135 ° 4 g/cm² ²: : 75 E 4 g/cm Interaction between Interaction between electron and electron and magnetic field magnetic field Detailed instrument GEANT4 model Detailed instrument GEANT4 model 9.4 TeV electron released at 400 km above the 9.4 TeV electron released at 400 km above the θ ) = ground at cos( θ ) = - -0.32. 416 photons are 0.32. 416 photons are ground at cos( generated and 115 photons survive through generated and the atmosphere . . 33
BaF 2 crystals (2 cm thick, Basic detector : 1024 BaF 2 crystals φ = 5 cm) read by 2 (2 cm thick, φ = 5 cm) read by 2” ” PMTs: PMTs: Basic detector : 1024 � � ⇒ segmented system to identify line of photons; � ⇒ photon energies 20 keV to 50 MeV; � Hermetic plastic scintillator veto paddles (2.6 m) with waveshifting fiber readout: ting fiber readout: Hermetic plastic scintillator veto paddles (2.6 m) with waveshif � � ⇒ ability to veto charged particles at as close to 100% efficiency as possible; � 2.4 m 2.4 m ⇒ fast (~1 ns) timing ensures � photons are synchrotron, not random background; Antarctic flight expected in 2010/2011 Detector area Detector area Veto Veto paddles paddles 2 ~5.8 m 2 Second flight in 2011/2012 ~5.8 m 2 in crystals only ~2.0 m 2 in crystals only ~2.0 m 34
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