Search for Dark Matter The AMS-02 Experiment Ignacio Sevilla Noarbe (CIEMAT, Madrid) on behalf of the AMS collaboration

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Outline The AMS experiment on the ISS. Dark matter and indirect search. Prospects for the AMS experiment.

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT The AMS experiment AMS (Alpha Magnetic Spectrometer) is a particle physics experiment in space. 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 Z=26, in the GeV-TeV range. It will detect and identify huge statistics of primary and secondary cosmic rays, up to Z=26, in the GeV-TeV range. Among its physics goals, are anti-matter and dark matter search, cosmic ray propagation studies. 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. 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 AMS-02 will be on the ISS for three years from early AMS-01 was tested successfully on shuttle flight STS91 for ten days in AMS-02 will be on the ISS for three years from early 2008.

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT The AMS experiment Superconducting magnet (BL 2 = 0.85 Tm 2 ) Silicon Tracker (rigidity, charge) Scintillator system (TOF) (β, dE/dx, trigger) Transition Radiation Detector (e/p) Ring Imaging Cherenkov (β, charge) Electromagnetic Calorimeter (energy, e/p) ~2 m; 7 Tons Geometrical acceptance: 0.45 m 2 sr ~2 m Also gamma rays in conversion or ECAL Anticoincidence counters, star-tracker, GPS

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Dark matter: neutralinos The case for non-baryonic dark matter is well established by several independent measurements and theoretical approaches. 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.  M h 2 = ± 0.008;  b h 2 = ±

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Dark 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.

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Gamma rays: –They are originated either from annihilation into a final state containing Zγ or γγ (line signal) or from the decay of other primary annihilation products (continuum signal). Positrons: –Primarily from the decay of gauge bosons (e.g.,W + W - ) as primary annihilation products; or from heavy quark/lepton decay Antiprotons and antideuterons: –Production in WIMP annihilations by hadronization of quark and gluon subproducts. Possible detectable products from:  xx with small physical backgrounds Balloons  ray telescopes and satellites AMS Indirect searches with AMS: detection channels

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: CR flux and energy ranges Particle Energy range p up to several TeV p GeV e up to O(TeV) e GeV He 1 up to several TeV anti – He…C 1 up to O(TeV) Light Isotopes 1-10 GeV/nucleon  GeV 1 p+ per second above 100 GeV 10 5 C after 3 years above 100 GeV Be after 3 years above 100 GeV AMS ~1/s AMS ~1/hour AMS ~1/day 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 m 2 sr and spectral index ~ 2.8

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: expected performances Positrons TRD selection up to 300 GeV; ECAL e/p selection with shower shape Overall Proton rejection of ~10 5 Acceptance ~4.5·10 -2 m 2 ·sr Antiprotons Charge confusion control for p+; TOF β, TRD, ECAL for e- Proton rejection of ~10 6 ; e - ~ 10 4 Acceptance ~3·10 -2 m 2 ·sr 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 m 2 ·sr from 10 GeV. Proton rejection 10 5 ; e - ~ 10 4

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: expected performances Positrons TRD selection up to 300 GeV; ECAL e/p selection with shower shape Overall Proton rejection of ~10 5 Acceptance ~4.5·10 -2 m 2 ·sr Antiprotons Charge confusion control for p+; TOF β, TRD, ECAL for e- Proton rejection of ~10 6 ; e - ~ 10 4 Acceptance ~3·10 -2 m 2 ·sr 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 m 2 ·sr from 10 GeV. Proton rejection 10 5 ; e - ~ 10 4

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: expected performances Positrons TRD selection up to 300 GeV; ECAL e/p selection with shower shape Overall Proton rejection of ~10 5 Acceptance ~4.5·10 -2 m 2 ·sr Antiprotons Charge confusion control for p+; TOF β, TRD, ECAL for e- Proton rejection of ~10 6 ; e - ~ 10 4 Acceptance ~3·10 -2 m 2 ·sr 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 m 2 ·sr from 10 GeV. Proton rejection 10 5 ; e - ~ 10 4

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: flux estimations Gas (HI,H 2,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 (π 0 production, inverse Compton, bremsstrahlung) Local Background Flux determined by propagation of CR yield per unit volume through simulation (GALPROP) φ (m -2 s -1 sr -1 GeV -1 ) = φ bg + φ signal

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT W. de Boer et al, hep-ph/ Indirect searches with AMS: flux estimations CR yield per unit volume (r,z,E) ≡ g ann (E). * *(ρ χ (r,z) /m χ ) 2 WMAP (+…) constraints on   h 2 ≡ coannihilation cross- section Rotational velocity measurements ρ χ (r,z) ≡ density distribution DM density profile shape (+ “boost factors * ”) Accelerator constraints Boost factors: clumpiness, cuspiness, baryon interaction, massive central black hole… g ann (E) ≡ particle production rate per annihilation SUSY parameter space (5+…) Local Flux determined by propagation of CR yield per unit volume through simulation (GALPROP) φ (m -2 s -1 sr -1 GeV -1 ) = φ bg + φ signal COSMOLOGY m χ ≡ neutralino mass ASTROPHYSICS HEP (propagation model and parameters …)

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: positron 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.

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT m  = 98 GeV M 0 = 60; m 1/2 = 250; tan β = 10; A 0 = 0 ~ Indirect searches with AMS: positron channel Positrons Sensitivity to B’ (“bulk”) and E’ (“focus point”) benchmark mSUGRA models (Battaglia et al. hep-ph/ ). For these and other benchmark scenarios, boost factors needed to fit HEAT data range from 10 3 to Credit: Jonathan Pochon - LAPP

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: positron channel Positrons Sensitivity to B’ (“bulk”) and E’ (“focus point”) benchmark mSUGRA models (Battaglia et al. hep-ph/ ). For these and other benchmark scenarios, boost factors needed to fit HEAT data range from 10 3 to Credit: Jonathan Pochon - LAPP m  = 124 GeV m 0 = 1530; m 1/2 = 300; tan β = 10; A 0 =0 ~

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: positron channel Positrons Sensitivity to HEAT, p -, EGRET-data fitted model (de Boer et al. hep-ph/ ). In this case,  bbbar favored (no sharp cutoff). Boost factor needed to fit HEAT data ~10 2 Credit: Jonathan Pochon - LAPP m  = 208 GeV m 0 = 500; m 1/2 = 500; tan β = 50; A 0 = 500 ~

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: positron channel Positrons More general mSUGRA scan: minimal “boost factors” for discovery. Boost factor needed quite sensitive to assumptions at GUT scale. Credit: Jonathan Pochon - LAPP

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: positron 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

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: antiproton 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).

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: antiproton channel Antiprotons Sensitivity to wide range of cases: Very favorable: flat spectrum (Ullio astro-ph/ ) (high mass ~1.4 TeV; high boost factor ~7·10 3 ).

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: antiproton channel Antiprotons Sensitivity to wide range of cases: De Boer et al. (hep-ph/ ) data-fitted model would be detectable (boost factor required of 6.5).

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: antiproton channel Antiprotons Sensitivity to wide range of cases: Conservative (no boost factor): detection/exclusion of AMSB scenarios (Profumo et al. hep-ph/ ).

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: antiproton channel Antiprotons Background calculations can be very much improved with B/C and other isotopic ratio measurements.

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Indirect searches with AMS: gamma channel Gamma rays Many experiments will be covering the little known 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. B B

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Summing up Recent research points to a non-baryonic component of dark matter. Neutralinos are one of the best candidates to date.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: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 >10 GeV will be confirmed or disproved. –Antiprotons: the spectrum at >50 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.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.

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Backup

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT The 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 m 3 of superfluid helium. BL 2 = 0.86 Tm 2

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT It will measure the rigidity (momentum/charge) and charge. With over 6 m 2 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  m will be achieved. This means around 200k channels. The AMS experiment: the Silicon Tracker

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT The 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).

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT 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 10 2 – 10 3 in the range 3 – 300 GeV. The AMS experiment: the Transition Radiation Detector

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT The 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. reflector PMT plane radiator

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT The 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.

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Gamma ray in a 3-prong e- event from test beam

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT From D.Hooper and J.Silk (astro-ph/ ) Sensitivity to bino-like LSP neutralinos up to 3· 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.

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT  0  1  m   m  0.1 Galactic Cluster Cosmological + Dark matter problem: observations SCALE OMEGA + CMB + SNIa observations Credit: BOOMERANG and the SN Cosmology Project Gravitational lensing Credit: HST Galaxy rotation curves Credit: Corbell, Salucci (1999)

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Dark matter problem: theoretical 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  (  varies quickly if not unity).

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT Dark 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…  M h 2 = 0.14 ± 0.02;  b h 2 = ± 0.001

Lisboa HEP /07/2005 Ignacio Sevilla Noarbe AMS-CIEMAT