Title: Search for Dark Matter The AMS02 Experiment
1Search for Dark MatterThe AMS-02 Experiment
- Ignacio Sevilla Noarbe
- (CIEMAT, Madrid)
- on behalf of the AMS collaboration
2Outline
- The AMS experiment on the ISS.
- Dark matter and indirect search.
- Prospects for the AMS experiment.
3The AMS experiment
- AMS (Alpha Magnetic Spectrometer) is a particle
physics experiment in space. - It will detect and identify huge statistics of
primary and secondary cosmic rays, up to Z26, in
the GeV-TeV range. - Among its physics goals, are anti-matter and
dark matter search, cosmic ray propagation
studies. - It is being mainly built in Europe, in close
collaboration with NASA, involving hundreds of
scientists and engineers and many institutions
worldwide. - AMS-01 was tested successfully on shuttle flight
STS91 for ten days in 1998. AMS-02 will be on the
ISS for three years from early 2008.
4The AMS experiment
- Superconducting magnet (BL2 0.85 Tm2)
- Silicon Tracker (rigidity, charge)
- Scintillator system (TOF) (ß, dE/dx, trigger)
- Transition Radiation Detector (e/p)
- Ring Imaging Cherenkov (ß, charge)
2 m 7 Tons
- Electromagnetic Calorimeter(energy, e/p)
- Anticoincidence counters, star-tracker, GPS
- Also gamma rays in conversion or ECAL
2 m
5Dark matter neutralinos
- The case for non-baryonic dark matter is well
established by several independent measurements
and theoretical approaches.
?Mh2 0.135 0.008 ?bh2 0.0224 0.0009
- From the observational point of view of AMS, one
of the best candidates for detection is the
neutralino, which presents other interesting
qualities - Supersymmetry predicts the existence of these
particles without an a priori requirement for a
WIMP dark matter candidate. - Neutral, weak-interacting and stable in R-parity
conserving SUSY models where the LSP is a
neutralino. - Current most accepted structure formation (?CDM)
theory require weakly-interacting massive
particles (WIMPs). - HOWEVER
- Neutralinos (or supersymmetry for that case)
have not been observed yet.
6Dark matter detection
- WIMP DM component detection
- Direct detection via inelastic scattering (DAMA,
CDMS, UKDMC). - Indirect detection
- Annihilation in Earth/Sun ? ?? ? (ANTARES,
ICECUBE) - Annihilation in galactic halo ?
- ANOMALIES IN CR SPECTRA
- These can be studied from balloon (BESS, CAPRICE)
and space-borne experiments (PAMELA, GLAST). - AMS on the International Space Station will
provide enough statistics to perform a
multi-channel approach.
7Indirect searches with AMSdetection channels
Possible detectable products from ???xx with
small physical backgrounds
- Gamma rays
- They are originated either from annihilation into
a final state containing Z? or ?? (line signal)
or from the decay of other primary annihilation
products (continuum signal). - Positrons
- Primarily from the decay of gauge bosons
(e.g.,WW-) as primary annihilation products or
from heavy quark/lepton decay - Antiprotons and antideuterons
- Production in WIMP annihilations by hadronization
of quark and gluon subproducts.
? ray telescopes and satellites
AMS
Balloons
8Indirect searches with AMSCR flux and energy
ranges
Particle Energy range p 0.1 up to
several TeV p- 0.5-300 GeV e-
0.1 up to O(TeV) e 0.1-300
GeV He 1 up to several TeV anti
HeC 1 up to O(TeV) Light Isotopes 1-10
GeV/nucleon g 1-1000 GeV
1 p per second above 100 GeV 105 C after 3 years
above 100 GeV 105 10Be after 3 years above 100 GeV
Approximate rates (horizontal lines) indicate
number of particles inside geometrical acceptance
integrated from the energy where the spectrum
crosses the line. We assume 0.45 m2sr and
spectral index 2.8
9Indirect searches with AMSexpected performances
- Positrons
- TRD selection up to 300 GeV ECAL e/p selection
with shower shape - Overall Proton rejection of 105
- Acceptance 4.510-2 m2sr
- Antiprotons
- Charge confusion control for p TOF ß, TRD, ECAL
for e- - Proton rejection of 106 e - 104
- Acceptance 310-2 m2sr up to 20 GeV
- Gamma rays ECAL(TRK)
- Angular resolution under 3º(0.1º) over 10 GeV.
- Energy resolution 5 over 10 GeV
- Acceptance ECAL(TRK) 5(3)10-2 m2sr from 10
GeV. - Proton rejection 105 e - 104
10Indirect searches with AMSexpected performances
- Positrons
- TRD selection up to 300 GeV ECAL e/p selection
with shower shape - Overall Proton rejection of 105
- Acceptance 4.510-2 m2sr
- Antiprotons
- Charge confusion control for p TOF ß, TRD, ECAL
for e- - Proton rejection of 106 e - 104
- Acceptance 310-2 m2sr up to 20 GeV
- Gamma rays ECAL(TRK)
- Angular resolution under 3º(0.1º) over 10 GeV.
- Energy resolution 5 over 10 GeV
- Acceptance ECAL(TRK) 5(3)10-2 m2sr from 10
GeV. - Proton rejection 105 e - 104
11Indirect searches with AMSexpected performances
- Positrons
- TRD selection up to 300 GeV ECAL e/p selection
with shower shape - Overall Proton rejection of 105
- Acceptance 4.510-2 m2sr
- Antiprotons
- Charge confusion control for p TOF ß, TRD, ECAL
for e- - Proton rejection of 106 e - 104
- Acceptance 310-2 m2sr up to 20 GeV
- Gamma rays ECAL(TRK)
- Angular resolution under 3º(0.1º) over 10 GeV.
- Energy resolution 5 over 10 GeV
- Acceptance ECAL(TRK) 5(3)10-2 m2sr from 10
GeV. - Proton rejection 105 e - 104
12Indirect searches with AMSflux estimations
f (m-2 s-1 sr-1 GeV-1) fbg fsignal
Local Background Flux determined by propagation
of CR yield per unit volume through simulation
(GALPROP)
Gas (HI,H2,HII) distribution
CR source distribution and spectrum (index,
abundances)
Diffusion model (reacceleration, diffusion) and
parameters (D,size h, cross-sections)
- Physical background
- Antimatter channels
- secondary products from cosmic ray spallation in
the interstellar medium - Gamma ray channel
- diffuse Galactic emission from cosmic ray
interaction with gas (p0 production, inverse - Compton, bremsstrahlung)
13Indirect searches with AMSflux estimations
f (m-2 s-1 sr-1 GeV-1) fbg fsignal
Local Flux determined by propagation of CR yield
per unit volume through simulation (GALPROP)
(propagation model and parameters )
CR yield per unit volume (r,z,E)
gann(E).ltsvgt(??(r,z) /m?)2
gann(E) particle production rate per
annihilation
COSMOLOGY
ASTROPHYSICS
WMAP () constraints on ??h2
Rotational velocity measurements
m? neutralino mass
DM density profile shape ( boost factors)
HEP
ltsvgt coannihilation cross-section
Accelerator constraints
??(r,z) density distribution
SUSY parameter space (5)
Boost factors clumpiness, cuspiness, baryon
interaction, massive central black hole
14Indirect searches with AMSpositron channel
- Positrons
- The relative fluxes of electrons and positrons
are very uncertain at energies above 10 GeV. - An excess of positron fraction is claimed by the
HEAT balloon experiment, maybe hinting to
neutralinos? - Discovery potential sensible to local DM
distribution. - High sensitivity to local clumpiness.
15Indirect searches with AMSpositron channel
m? 98 GeV M0 60 m1/2 250 tan ß 10 A0
0 ltsvgt 10-27
Credit Jonathan Pochon - LAPP
- Positrons
- Sensitivity to B (bulk) and E (focus point)
benchmark mSUGRA models (Battaglia et al.
hep-ph/0306219). - For these and other benchmark scenarios, boost
factors needed to fit HEAT data range from 103 to
105.
16Indirect searches with AMSpositron channel
m? 124 GeV m0 1530 m1/2 300 tan ß 10
A0 0 ltsvgt 10-29
Credit Jonathan Pochon - LAPP
- Positrons
- Sensitivity to B (bulk) and E (focus point)
benchmark mSUGRA models (Battaglia et al.
hep-ph/0306219). - For these and other benchmark scenarios, boost
factors needed to fit HEAT data range from 103 to
105.
17Indirect searches with AMSpositron channel
m? 208 GeV m0 500 m1/2 500 tan ß 50
A0 500 ltsvgt 10-26
Credit Jonathan Pochon - LAPP
- Positrons
- Sensitivity to HEAT, p-, EGRET-data fitted model
(de Boer et al. hep-ph/0309029). - In this case, ???bbbar favored (no sharp cutoff).
- Boost factor needed to fit HEAT data 102
18Indirect searches with AMSpositron channel
Credit Jonathan Pochon - LAPP
- Positrons
- More general mSUGRA scan minimal boost factors
for discovery. - Boost factor needed quite sensitive to
assumptions at GUT scale.
19Indirect searches with AMSpositron channel
- Positrons
- Alternative scenario the lightest Kaluza-Klein
particle in the Universal Extra Dimensions model
(a 300 GeV KK photon in this case). - Boost factor needed 1700 to fit HEAT data, 60
for discovery.
Credit Jonathan Pochon - LAPP
20Indirect searches with AMSantiproton channel
- Antiprotons
- They seem to follow expected spectrum from CR
interaction with ISM up to 10 GeV. - However there are large uncertainties above 10
GeV and below 1 GeV (though now disfavored in
this region).
21Indirect searches with AMSantiproton channel
Antiprotons
- Sensitivity to wide range of cases
- Very favorable flat spectrum (Ullio
astro-ph/9904086) (high mass 1.4 TeV high boost
factor 7103).
22Indirect searches with AMSantiproton channel
Antiprotons
- Sensitivity to wide range of cases
- De Boer et al. (hep-ph/0309029) data-fitted model
would be detectable (boost factor required of
6.5).
23Indirect searches with AMSantiproton channel
Antiprotons
- Sensitivity to wide range of cases
- Conservative (no boost factor)
detection/exclusion of AMSB scenarios (Profumo et
al. hep-ph/0406018).
24Indirect searches with AMSantiproton channel
Antiprotons
- Background calculations can be very much
improved with B/C and other isotopic ratio
measurements.
25Indirect searches with AMSgamma channel
B
B
- Gamma rays
- Many experiments will be covering the little
known 1-300 GeV range in the next decade. - Case considered Galactic center treated as point
source. Favorable conditions to detect or exclude
AMSB scenarios benchmark points of parameter
space accesible in case of cuspy profile as well
as several KK candidates.
26Summing up
- Recent research points to a non-baryonic
component of dark matter. Neutralinos are one of
the best candidates to date. - AMS will be a multipurpose detector in space that
will look for signatures of neutralino
coannihilation in the galactic halo, making use
of high statistics, particle identification and
multichannel capabilities - B/C and Be ratios will impose severe constraints
to galaxy models and diffusion parameters for
background estimation. - Positrons signal at gt10 GeV will be confirmed or
disproved. - Antiprotons the spectrum at gt50 GeV will be
measured with great sensitivity. - Gammas (from Galactic Center) visible signal in
cuspy profile scenarios or other boost factors. - A single experiment that will enable a
simultaneous study of several cases of the MSSM
parameter space as well as other scenarios such
as KK-particles and AMSB neutralinos.
27Backup
28The AMS experiment the superconducting magnet
- Its purpose is to bend the trajectories of
charged particles. - It will be the first superconducting magnet to
operate in space. - It is a system of 12 racetrack coils 2 dipole
coils cooled to 1.85 K by 2.5 m3 of superfluid
helium. - BL2 0.86 Tm2
29The AMS experiment the Silicon Tracker
- It will measure the rigidity (momentum/charge)
and charge. - With over 6 m2 of active surface, it will be the
largest ever built before the LHC. - Based on 8 thin layers of double-sided silicon
microstrips, a spatial resolution of 10 mm will
be achieved. - This means around 200k channels.
30The AMS experiment the Time Of Flight system
- This sub-detector will measure the velocity of
the particle by recording time of passage and
position in 4 different planes. - Each plane has 8-10 scintillator paddles seen by
2 PMTs on each side. - It can measure velocities with 3.6 relative
error (for ? 1 protons).
31The AMS experiment theTransition Radiation
Detector
- The TRD is based on the radiation emitted by a
moving charged particle when it traverses two
different media. - It will perform hadron/lepton separation.
- There are 20 layers of foam separated by drift
tubes. - h/e rejection of 102 103 in the range 3 300
GeV.
32The AMS experiment the RICH detector
- Makes use of the Cherenkov light emitted in the
radiator by relativistic charged particles. - We can obtain the velocity and absolute charge of
incoming particles. - 3 cm thick aerogel radiator 680 multianode
photomultipliers. - We can achieve velocity measurements with a 0.1
relative error for protons. - CIEMAT is a major partner in this effort.
33The AMS experiment the Electromagnetic
Calorimeter
- The ECAL registers electromagnetic showers
initiated by the particles. - Thus we can measure the energy of the primary.
- It consists of 9 superlayers of scintillator/lead
connected to 324 multianode photomultipliers. - Energy is measured with a 3 error at 100 GeV.
34Gamma ray in a 3-prong e- event from test beam
35From D.Hooper and J.Silk (astro-ph/0409104)
- Sensitivity to bino-like LSP neutralinos up to
310-27 for masses 100 GeV. - Sensitivity to LSP neutralinos in AMSB scenarios
up to several hundred GeV (even a few TeV). - Sensitivity to annihilations of KK excitations of
SM fields up to 1 TeV.
36Dark matter problem observations
OMEGA
SCALE
?m ? 0.1
Galactic
Cluster
?m ? 0.2-0.3
Cosmological
?0 ? 1
37Dark matter problemtheoretical arguments
- CMB characteristics are better explained in
inflationary models. (Most of) these in turn
predict ? 1.
- If ?lum ?mass it turns out that structure
should have formed rapidly requiring unobserved
high fluctuations in the CMB.
- If ? ? 1, as we know that ?0 1 now, at Planck
time it should have been 1?10-60 (? varies
quickly if not unity).
38Dark matter problem candidates
- The case for non-baryonic DM
- limited by well-tested BBN Deuterium and He-3
observations. - observations from MACHO experiments cannot
account for all galactic dark matter. - CMB acoustic peaks power spectrum of universal
inhomogeneity cluster baryon fraction implies -
- One of the best descriptions to date for
structure formation ?CDM scenario requires
WIMPs (or axions). - Candidates neutrinos, SUSY particles, axions,
Kaluza-Klein particles, many others
?Mh2 0.14 0.02 ?bh2 0.024 0.001
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