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Akira Yamamoto (KEK) for the BESS collaboration SpacePart-06, Beijing, April 20, 2006. The BESS Program. Outline. BESS Experiment and Spectrometer Recent and New Results BESS TeV : Precise measurement of cosmic-rays BESS-Polar I : Search for antiparticle of primary origin

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Akira yamamoto kek for the bess collaboration spacepart 06 beijing april 20 2006

Akira Yamamoto (KEK)

for the

BESS collaboration

SpacePart-06, Beijing, April 20, 2006

The BESS Program


Outline
Outline

  • BESS Experiment and Spectrometer

  • Recent and New Results

    • BESS TeV : Precise measurement of cosmic-rays

    • BESS-Polar I : Search for antiparticle of primary origin

  • Plan for future

  • Summary


  • High Energy Accelerator

    Research Organization(KEK)

    The University

    of Tokyo

    Kobe University

    Institute of Space and

    Astronautical Science/JAXA

    BESS Collaboration

    As of April, 2006

    National Aeronautical and

    Space Administration

    Goddard Space Flight Center

    BESS

    Collaboration

    University of Maryland

    University of Denver

    (Since June 2005)


    Balloon-borne

    Experiment with a

    Superconducting

    Spectrometer

    Search for

    Primordial Antiparticle

    antiproton: Novel primary origins (PBH,DM)

    antihelium: Asymmetry of matter/antimatter

    Precise Measurement of Cosmic-ray flux:

    highly precise measurement at < 1 TeV

    BESS


    Bess detector

    Rigidity measurement

    SC Solenoid (L=1m, B=1T)

    Min. material (4.7g/cm2)

    Uniform field

    Large acceptance

    Central tracker

    (Drift chamber

    d ~200mm

    Z, m measurement

    R,b --> m = ZeR 1/b2-1

    dE/dx --> Z

    BESS Detector

    • JET/IDC

    • Rigidity

    TOF

    b, dE/dx


    Bess tev deflection resolution

    MDR 1.4 TV

    BESS-98

    MDR 200 GV

    BESS-TeV Deflection Resolution


    Bess tev spectrometer
    BESS-TeV Spectrometer

    TOF

    ODC

    MAGNET

    • JET/IDC


    Progress of bess experiment
    Progress of BESS Experiment

    1993~ 2000, BESS, North Canada

    2002, BESS-TeV

    1999, 2001, BESS-Ground, Japan

    2001, BESS-TeV, Fort Sumner

    2004, BESS-Polar I, Antarctica

    10 scientific balloon flightsduring1993-2004


    Primary cosmic ray spectra 1998 bess 98 ams i caprice
    Primary Cosmic-ray Spectra (1998: Bess-98, AMS-I, Caprice)

    Error: < +/-5 %

    @ 100 GeV

    Sanuki et al. ApJ. 545 (2000) 1135


    Primary cosmic ray spectra bess tev
    Primary Cosmic-ray Spectra (BESS-TeV)

    Error: < +/-15 %

    @ 500 GeV

    Haino et al. PLB 594 (2004) 35


    Bess tev result anchor the p and he spectra in low energy tev

    F = f Ek-g

    Proton (Ek> 30 GeV)

    f = (1.37 ± 0.12)x104

    g= 2.732 ± 0.022

    Helium (Ek> 20 GeV)

    f = (7.06 ± 1.15)x102

    g= 2.699 ± 0.059

    Fitting based on the BESS-TeV results only

    BESS-TeV Result Anchor the P and He Spectra in Low Energy (< TeV)


    Low energy cosmic ray spectra precisely measured by bess

    Rigidity Measurement

    Precise spectra

    proton (0.2~500 GeV)

    helium (0.2~250 GeV/n)

    antiproton (0.2~ 4 GeV)

    Anchor the spectrum

    in the lowest energy region.

    104

    • BESS

    Flux (m2 sr s GeV)-1

    10-28

    0.1

    1012

    Energy (GeV)

    Low Energy Cosmic-ray SpectraPrecisely Measured by BESS


    Search for Antiprotons of Cosmic Origins

    Primary Detectable

    Secondary

    SUSY

    PBH

    • Most antiprotons are secondary products from nuclear interactions of primary cosmic rays with the ISM.

    • “Exotic” sources may relatively enhance antiproton flux at energies well below or above secondary peak.


    Observation of Cosmic-rayAntiprotonsin p-bar/p Ratio

    1979:First observation (Golden et al)

    1979: Russian PM (Bogomolov et al)

    1981: Excess reported (Buffington et al)

    1985: ASTROMAG Study Started

    1987:LEAP, PBAR (upper limits)

    1991: MASS

    1992:IMAX (16 antiprotons)

    1993:BESS (6 antiprotons), TS93

    1994:CAPRICE94, HEAT-e

    1996: Solar minimum

    1998: CAPRICE98, AMS-01

    2000: HEAT-pbar

    2004:BESS-Polar

    2006:PAMELA

    2007: Solar minimum, BESS-Polar

    2008:AMS-02

    Before the BESS Experiment


    p/p Ratio

    Observation of Cosmic-rayAntiprotonsin p-bar/p Ratio

    1979:First observation (Golden et al)

    1979: Russian PM (Bogomolov et al)

    1981: Excess reported (Buffington et al)

    1985: ASTROMAG Study Started

    1987:LEAP, PBAR (upper limits)

    1991: MASS

    1992:IMAX (16 antiprotons)

    1993:BESS (6 antiprotons), TS93

    1994:CAPRICE94, HEAT-e

    1996: Solar minimum

    1998: CAPRICE98, AMS-01

    2000: HEAT-pbar

    2004:BESS-Polar

    2006:PAMELA

    2007: Solar minimum, BESS-Polar

    2008:AMS-02

    BESS

    By the BESS Experiment


    Low energy cosmic ray antiprotons in last solar minimum 1995 97

    Mostly secondary particles

    with specific peak at 2 GeV

    Study:

    Propagation model

    Solar modulation

    Search for:

    Novel Primary Origin?

    (PBH, DM)

    Flatter spectrum in low energy

    10-1

    BESS(95+97)

    BESS(93)

    IMAX

    CAPRICE

    Pbar flux [m-2sr-1sec-1GeV-1]

    10-2

    10-3

    10-1

    1

    10

    Kinetic Energy (GeV)

    Low Energy Cosmic-ray Antiprotonsin last solar minimum (1995~97)

    More Statistics necessary ->> Long-duration Flight


    Bess polar experiment

    Very precise measurement

    Low energy Antiprotons

    Around south-pole, Antarctica

    Long duration flight

    High latitude

    Solar minimum

    With a new spectrometer

    Ultimately small material

    Ultra-thin superconducting solenoid

    BESS-Polar Experiment


    BESS-2000

    BESS-Polar

    TOF Upper

    Coil

    JET/IDC

    MTOF

    5g/cm2

    ACC

    18g/cm2

    10g/cm2

    TOF Lower

    Feature of BESS-Polar Spectrometer

    Minimize material in spectrometer

    New detector (Middle TOF)

    Energy range extended

    down to 0.1 GeV

    Low power electronics

    Solar Power System, Longer life of cryogen, LHe

    Long duration flight


    8.5 dayflight successful

    35-37 km in altitude

    900 million events recorded

    - Acceptance limited to ~ 0.2 m2.sr

    Altitude~38000m

    Residual air~4g/cm2

    Floating

    BESS-Polar 2004


    Low energy antiproton observed in bess polar i in 2004
    Low Energy Antiproton Observedin BESS Polar I (in 2004)

    Preliminary

    ~2000

    Antiproton

    Candidates

    • ~ 2000 antiproton (total) candidate observed

    • ~ 400 antiprotons below 1 GeV


    Lowest Energy Events Observed

    Antiproton

    event

    RGT -0.4GV

    1/β 2.47

    Limit by

    MTOF Trigger

    Limit by

    BTOF Trigger

    ★Kinetic Energy ~0.11GeV (@ TOA)

    ★Multi-track events to be further studied


    Antiprotons observed preliminary

    PMT-HV

    Both-end

    Single-end

    Dead

    Antiprotons Observed(Preliminary)

    • 4~5 times statistics

    • (than that of 1997),

    • With ~0.2 m2sr (2/3),

    • 8 days flight

    18/44 TOF-PMT turned-off


    Pbar p ratio observation extended
    Pbar/P Ratio Observation Extended

    • The measurement consistent with the prediction,

    Bieber et al.


    Progress in antihelium search
    Progress in Antihelium Search

    • Preliminary Results

      • The upper limit of antihelium/helium ratio pushed down

        • ~5 x 10E-7 @ BESS-Polar I

      • Generally, two order of magnitude lowered by BESS in last ten years.


    Further plan for bess polar ii

    Solar minimum in 2006~07

    Realize further long duration flight of 20 days with two circle around the pole, 4~5 x BESS-Polar I statistics

    Further Plan for BESS-Polar II

    Record at Tiger flight



    Bess polar ii observation expected
    BESS Polar II Observation(Expected)

    Antiproton Spectrum Search for Antideuteron and AntiHelium

    (Search for PBH)


    Bess polar feature
    BESS-Polar Feature

    (3 years)

    (10+20 days)

    AMS02

    PAMELA

    (3 years)

    BESS-Polar realize

    the best sensitivity in lowest energy

    Acceptance

    (m2sr)

    Flight Time

    Latitude

    Altitude

    (km)

    Launch

    AMS

    0.5

    3 years

    < 51.7

    280~500

    2008

    PAMELA

    0.0021

    3 years

    <70.4

    350-600

    2006

    BESS-Polar2

    0.3

    20 days

    > 75

    36

    2007


    Summary
    Summary

    • BESS measured:

      • Precise Cosmic-rayProton (Helium)spectrum with errors within

        • 5 % @ 100 GeV, and 15 % @ 500 GeV

        • with anchoring the spectrum at the lowest energy

      • Low energy Antiprotonspectra at 0.1 - 4 GeV to

        • Mostly secondaries,

        • Useful information on cosmic-ray propagation and solar modulation

        • Search for novel primary origin suchs as PBH,

      • Antidueteron search with the first upper limit reported,

      • Antihelium search reaching down to the upper limit ~3 x 10-7

    • BESS-PolarII planned, and important for

      • Ultimately sensitive search for primordial antiparticle with the long duration flight in solar minimum in 2007, and

      • Further precise measurement of cosmic rays, in a complimentary approach to PAMELA and AMS.


    Cosmic ray antiprotons observed by bess
    Cosmic-ray Antiprotons Observed by BESS

    10-1

    BESS(95+97)

    BESS(93)

    IMAX

    CAPRICE

    Pbar flux [m-2sr-1sec-1GeV-1]

    Solar Minimum

    10-2

    • More than 4000 antiprotons (candidates) observed

    10-3

    10-1

    1

    10

    Kinetic Energy (GeV)


    BESS-Polar

    ●Trigger Configuration

    ★UL Trigger

    ★UM Trigger



    Tof pmt problem and improvement of housing
    TOF PMT Problem and Improvement of Housing

    PMT-HV

    Both-end

    Single-end

    Dead

    18/44 PMTs turned off due to low pressure discharge and excessive current Geometrical Acceptance limited to 67 %

    PMT housing to be improved by using pressure vessel as on BESS-Polar I ACC, instead of Resin Potting


    Tof pmt problem and improvement of housing1
    TOF PMT Problem and Improvement of Housing

    PMT-HV

    Both-end

    Single-end

    Dead

    18/44 PMTs turned off due to low pressure discharge and excessive current Geometrical Acceptance limited to 67 %

    PMT housing to be improved by using pressure vessel as on BESS-Polar I ACC, instead of Resin Potting


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