INFN, Sezione di Roma 2 &

(1)

Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata

Particle Physics with

Space Detectors

Aldo Morselli

INFN, Sezione di Roma 2 &

Università di Roma Tor Vergata

(2)

To study gamma ray and cosmic ray in the MeV- GeV range you need to go outside the atmosphere

Why you want to study these items if you are a particle physicist?

• Nature of Dark Matter

(possible connection with supersymmetry)

• Quantum gravity limits

• Cosmic accelerators

Basic problem:

(3)

Cosmic Accelerators

Man-made Accelerators Cosmic Accelerators

GRB?

(4)

What is the Universe made of ?

Bright stars: 0.5%

Baryons (total): 4.4% ± 0.4%

Matter: 27% ± 4%

Cold Dark Matter: 22.6% ± 4%

Neutrinos: < 0.15%

Dark Energy: 73% ± 6%

h=0.71 + 0.04 - 0.03

W _m ^~0.3 W ^~0.7

WMAP+SN+HST

astro-ph/0302209

astro-ph 0007333

(5)

Candidates for Galactic Dark Matter

• Massive Compact Halo Objects (MACHOs)

• Low (sub- solar) mass stars. Standard baryonic composition.

• Use gravity microlensing to study.

• Could possibly account for 25% to 50% of Galactic Dark Matter.

• Neutrinos

• Small contribution if atmospheric neutrino results are correct, since m

_n

< 1eV.

• Large scale galactic structure hard to reconcile with neutrino dominated dark matter

• Weakly Interacting Massive Particles ( WIMPs)

• Non- Standard Model particles, ie: supersymmetric neutralinos

• Heavy (> 10GeV) neutrinos from extended gauge theories.

(6)

Neutralino WIMPs

Assume c present in the galactic halo

• c is its own antiparticle => can annihilate in galactic halo producing gamma-rays, antiprotons, positrons….

• Antimatter not produced in large quantities through standard processes (secondary production through p + p --> p + X)

• So, any extra contribution from exotic sources (c c annihilation) is an interesting signature

• ie: c c --> p + X

• Produced from (e. g.) c c --> q / g / gauge boson / Higgs boson and

(7)

Supersymmetry introduces free parameters:

In the MSSM, with Grand Unification assumptions the masses and couplings of the SUSY particles as well as their production cross sections, are entirely described once five parameters are fixed:

• ^M

_1/2

the mass parameter of s upersymmetric partners of gauge fields (gauginos)

• the higgs mixing parameters m that appears in the neutralino and chargino mass matrices

• ^m

₀

, the common mass for scalar fermions at the GUT scale

• A, the trilinear coupling in the Higgs sector

• the ratio between the two vacuum expectation values of the Higgs fields defined as:

tang b ^{= v}

₂

^{/ v}

₁

^{= <H}

₂

> / <H

₁

>

Experimental lower limit on the mass of the lightest neutralino assuming MSSM

(Minimal Standard Supersymmetric Model)

hep-ph/0004169

Lep , s = 189 GeV

M _c > 50 GeV ⁽ ⁾

(3

_S

)

(8)

EGRET data & Susy models

~2 degrees around the galactic center

EGRET data

A.Morselli, A.Lionetto, A.Cesarini, F.Fucito, P.Ullio, 2002

Annihilation channel b-bbar M c =50 GeV

background model(Galprop)

WIMP annihilation (DarkSusy)

Total Contribution

(9)

Main Diagrams for Neutralino Annihilation

gauge bosons

fermions

Light fermion pairs suppressed due to Pauli Principle (neutralinos are Majorana particles and fermions fi Pauli Principle at zero momentum fi p wave fi µ fermion mass !)

Low values of tan b (<3.8 excluded by electroweak data (g2, LEP Higgs Limit and BR(bôsg)

At larger values of tan b , bbar

dominant final state ( orders of

magnitudes for tan b >5 )

(10)

Differential yield for each annihilation channel

WIMP mass=200GeV

total yields

yields not due to p

⁰

decay

(11)

Differential yield for b bar

neutralino mass

(12)

Total photon spectrum from the galactic center from cc ann.

g lines

50 GeV 300 GeV

Infinite energy resolution

With finite energy resolution

• Two-year scanning mode

(6

_S

)

(13)

HALO SUBSTRUCTURE

A.Font and J.Navarro, astro- ph/ 0106268

600 kpc

Milky Way

(14)

A.Morselli, A.Lionetto, A.Cesarini, F.Fucito, P.Ullio, 2003

~2 degrees around the galactic center, 2 years data

(Galprop)

(one example from DarkSusy)

GLAST Expectation & Susy models

Annihilation channel W

⁺

W

^-

m

_x

=80.3 GeV

(15)

Positron with HEAT

ICRC 01 p.1867

Energy(GeV)

Positron fraction e

+

/ ( e

+

+ e

-

)

(16)

Positron with HEAT

ICRC 01

(17)

Positron Ratio

(Phys.Rev. D59 (1999) astro-ph 98008243)

•Background from normal secondary production

•Signal from ~ 300 GeV neutralino annihilations

Caprice94 data from ApJ , 532, 653, 2000

(ApJ 493, 694, 1998)

• Caprice98 data from

XXVI ICRC, OG.1.1.21, 1999

Total

Signal from neutralino annihilations

Background from normal

secondary production

(18)

PAMELA

POSITRONS

expectation

Secondary production

‘Leaky box model’

Secondary production

‘Moskalenko + Strong model’ without

reacceleration

Primary production from c c

annihilation

(m(c) = 336 GeV)

Primary production

for 3 years of operation

Secondary production

Total

(19)

AMS98

Background from normal secondary production

Signal from 964 GeV neutralino annihilations

( astro-ph 9904086)

Mass91 data from

XXVI ICRC, OG.1.1.21 , 1999 Caprice94 data from

ApJ, 487, 415, 1997

Caprice98 data from ApJ, 561, (2001), 787.

astro-ph/0103513

Distortion of the secondary antiproton flux induced by a signal from a heavy Higgsino-like neutralino.

Particles and photons are sensitive to

different neutralinos.

Gaugino-like particles are more likely to produce an observable flux of antiprotons whereas Higgsino-like

annihilations are more likely to produce an observable

gamma-ray signature

∆

BESS data from

Phys.Rev.Lett, 2000, 84, 1078

AMS data : preliminary

BESS 00

(20)

Secondary production

(upper and lower limits)

Simon et al.

Primary production from c c

annihilation

(m(c) = 964 GeV)

Secondary production

Primary production

PAMELA

ANTIPROTONS

expectation

(21)

Distortion on the secondary antiproton flux induced by an Extragalactic Antimatter component

• Background from normal secondary production

• Mass91 data from

XXVI ICRC, OG.1.1.21 , 1999

• CAPRICE94 data from ApJ , 487, 415, 1997

• CAPRICE98 data from ApJ Letters 534, L177, 2000

• HEAT 00 data from

Phys.Rev.Lett. 87 (2001) 271101 astro-ph/0111094

• BESS data from

Phys.Rev.Lett. 88 (2002) 051101 astro-ph/0109007

Extragalactic Antimatter

Primordial Black Hole evaporation

Antiproton/proton Ratio

Kinetic Energy (GeV) BESS 00

00

(22)

ANTIMATTER LIMITS

2003

(23)

MASS Matter Antimatter Space Spectrometer

(24)

The CAPRICE 94 flight

(25)

CAPRICE 94

(26)

CAPRICE98

Proton energy spectrum

at the top of

atmosphere

(27)

The helium energy

spectrum at the top of atmosphere

CAPRICE98

(28)

SilEye on MIR Space Station

wizard.roma2.infn.it

(29)

The complete detector

NINA 2 on MITA

Launch of NINA 1 : 10/8/1998 Launch of NINA 2 : 15/7/2000

More info: http://wizard.roma2.infn.it

The basic silicon detector The basic silicon detector

The NINA instrument

NINA2-MITA Launch

a silicon wafer 6x6 cm

²

, 380 mm thick with 16 strips, 3.6 mm wide

in two orthogonal views X -Y

(30)

PAMELA

RESURS-DK1 Satellite Mass: 10500 Kg

Elliptical Orbit 70.4° incl.

300-600 Km altitude

Launch: December 2003

Physics Objectives

® AntiProton spectrum : 80 MeV - 180 GeV

® Positron spectrum : 50 MeV - 200 GeV

® Search for Antinuclei

® e ⁺ + e ^- up to 1 TeV

® Multi TeV electrons

® Solar and Trapped Cosmic Rays

® Solar Energetic Particles

® Long Term Solar Modulation

® Radiation Belts Transient Phenomena

Bare Mass: 450 Kg Total Mass: ~750 Kg Power: 350 W

GF: 21 cm ² sr

MDR: 740 GV/c

(31)

Pamela

TRD TRD TRK TRK

ND ND TOF TOF

ANTI ANTI

CALO CALO

Total Mass 440 Kg Power 355 W

MDR – 770 GV

Protons 80 MeV – 700 GeV Antiprotons 80 MeV –190 GeV Electrons 50 MeV – 2 TeV Positrons 50 MeV - 270 GeV Nuclei < 700 GeV/n

Limits for Antinuclei ~10

^-8

(32)

O. Adriani

¹

, M. Ambriola

²

,, G. Barbiellini

³

,L.M. Barbier

⁴

,S. Bartalucci

⁵

, G. Bazilevskaja

⁶

, R. Bellotti

²

, D.

Bergstrom

⁷

, 5. Bertazzoni

⁸

, V. Bidoli

⁹

, M. Boezio

³

, E. Bogomolov

¹⁰

, V. Bonvicini

³

, M. Boscherini

¹

, U. Bravar

¹⁴

, F. Cafagna

²

, P. Carlson

⁷

, M. Casolino

⁸

, M. Castellano

²

, G. Castellini

¹⁵

, E.R. Christian

⁴

, F. Ciacio

²

, M. Circella

²

,

R. D’Alessandro

¹

, G. De Cataldo

²

, C.N. De Marzo

²

, M.P. De Pascale

⁹

, N.Finetti

¹

, T. Francke

⁷

, G. Furano

⁹

, A.

Gabbanini

¹⁵

, A.M. Galper

¹¹

, N. Giglietto

²

, M. Grandi

¹

, A. Grigorjeva

⁶

, M. Hof

¹²

, S.V. Koldashov

¹¹

, M.G.

Korotkov

¹¹

, J.F. Krizmanic

⁴

, S. Krutkov

¹⁰

, B. Marangelli

²

, L. Marino

⁵

, W. Menn

¹²

, V.V. Mikhailov

¹¹

, N.

Mirizzi

²

, J.W. Mitchell

⁴

, A.A. Moiseev

¹¹

, A. Morselli

⁹

, R. Mukhametshin

⁶

, J.F. Ormes

⁴

, J.V. Ozerov

¹¹

, P.

Papini

¹

, A. Perego

¹

, S. Piccardi

¹

, P. Picozza

⁹

, M. Ricci

⁵

, A. Salsano

⁸

, P. Schiavon

³

, M. Simon

¹²

, R. Sparvoli

⁹

, B.

Spataro

⁵

, P. Spillantini

¹

, P. Spinelli

²

, S.A. Stephens

¹³

, S.J. Stochaj

¹⁴

, Y. Stozhkov

⁶

, R.E. Streitmatter

⁴

, F.

Taccetti

¹⁵

, M. Tesi

¹⁵

, A. Vacchi

³

, E. Vannuccini

¹

, G. Vasiljev

¹⁰

, V. Vignoli

¹⁵

, S.A. Voronov

¹¹

, N. Weber

⁷

, Y.

Yurkin

¹¹

, N. Zampa

³

1 University and INFN, Firenze (Italy)

2 University and INFN, Bari (Italy)

3 University and INFN, Trieste (Italy)

9 University of Roma “Tor Vergata” and INFN Roma2, Roma, (ltaly)

10 Ioffe Physical Technical Institute (Russia)

11 Moscow Engineering and Physics Institute, Moscow (Russia)

The Wizard Group

(33)

GLAST

… 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 ...

Past, Present and Future Projects Past, Present and Future Projects

C 94 C 97 C 98

TS 93

M 89 M 91

MASS-89, 91, TS-93,

CAPRICE 94-97-98 PAMELA

PAMELA

NINA-2

NINA-1

NINA-1 NINA-2

SILEYE-2 SILEYE-1

ALTEINO: SILEYE-3

ALTEA:

SILEYE-4 SILEYE-1

SILEYE-2

SILEYE-3

SILEYE-4

GLAST

WiZard Program

AGILE

(34)

Presurized container with

PAMELA in operating position

PAMELA in launching

position

field of

view Expected Date of launch : end of 2003

PAMELA Launch

(35)

More information on PAMELA :

please visit us:

http://wizard.roma2.infn.it/

(36)

AMS Lancio: 2004-5 Durata: 3 anni

Protoni fino ad alcuni TeV Antiprotoni fino a 200

GeV

Elettroni fino al TeV

Positroni fino a 200 GeV

Nuclei fino ad alcuni TeV

AntiNuclei fino al TeV

g fino a 100 GeV

(37)

AMS

Altezza: 320-390 Km Altezza: 320-390 Km

Inclinazione 51.7

Inclinazione 51.7 ° °

(38)

AGILE

(39)

AGILE

AntiCoincidence

Photomultipliers

Top: 0.5cm plastic scintillator Lateral: 12 panels 0.6 cm

1.5 X

⁰

CsI Calorimeter 1.4240 cm

³

bars

X/Y plane, 121 mm pitch

distance between planes 1.6cm

W 0.07 X

0

Super Agile Mask

Super Agile Silicon plane

Tracker , 14 X/Y planes

Calorimeter

(40)

More information on AGILE :

please visit us:

http://www.ifctr.mi.cnr.it/agile/

http://www.roma2.infn.it/infn/agile/

(41)

GLAST

(42)

Grid

Tracker

ACD Thermal

Blanket

Anticoincidence Shield

Silicon Tracker tower

18 planes of X Y silicon detectors + converters 12 trays with 2.5% R.L. of Pb , 4 trays with 25% ,

2 trays without converters 1.68 m

84 cm

Gamma-Ray Large Area Space Telescope

(43)

GLAST Instrument Description

EGRET GLAST simulation

Geminga

Crab

Geminga

Crab IC 443

l General Characteristics: imaging, wide field- of-view, pair-conversion telescope, backed by EM calorimetry using modern HEP technology:

* energy range: 10 MeV to 300 GeV

* energy resolution: 10%

* effective area: > 8,000 cm ² (above 1 GeV)

* field-of-view: ~2p sr

* point source sensitivity: 2 x 10 ^-9 ph cm ^-2 s ^-1 (@ 100 MeV) 10 ^-10 ph cm ^-2 s ^-1 ( > 1 GeV)

* source location determination: 30 arcsec - 5 arcmin

* cosmic ray/g rejection > 10 ⁵ to 1

(44)

GLAST Performance

(45)

In scanning mode, the LAT will achieve after one day sensitivity sufficient to detect (5s) the weakest EGRET sources

All 3EG sources + ~ 80 new in 2 days

fi periodicity searches (pulsars, X-ray binaries)

fi pulsar beam, emission vs.

luminosity, age, B

GLAST LAT Strength

- New EGRET Catalog Every 2 days -

(46)

One year All-Sky Survey Simulation, Eg > 100 MeV

All-sky intensity map based on five years EGRET data.

All-sky intensity map from a GLAST one year survey,

based on the extrapolation of the EGRET

GLAST

(47)

GRB studies with GLAST

EGRET observed delayed GeV emission from the GRB of February 17, 1994, including a 20 GeV photon that arrived 80 minutes after the burst began.

GLAST will make the definitive measurements of the high-energy behaviour

of GRBs and GRB afterglows.

(48)

GRB studies with GLAST ⁽²⁾

• Broad band spectral information: ~ 200 keV - 30 GeV

• Rapid (few seconds) communication of GRB quicklook results

• Study of the initial

impulsive phase:

Dt< 1 ms

• Expected

detection rate

(above 50 MeV):

50-100 yr ^-1

(49)

Gamma ray missions deadtime

Gamma -ray mission deadtime

(50)

Test of Quantum Gravity ⁽¹

^q

⁾

Candidate effect:

c ² P ² = E ² ( 1+ f(E/E _QG ))

E=photon energy E

_QG

=effective quantum gravity energy scale

Deformed dispersion relation with function f model dependent function of E/E

_QG

if E< < E

_QG

series expansion is applicable

c

²

P

²

= E

²

( 1+ a ^(E/E

_QG

⁾⁺ O ^(E/E

_QG

⁾

²

⁾ v = d ^E/ d P ~ c ( 1+ a ^(E/E

_QG

⁾⁾

vacuum as quantum-gravitational medium which respond differently to the propagation of particle of different energies.

(analogous to propagation through an electromagnetic plasma) Medium fluctuation at a scale of the order of L

_p

~10

^-33

cm

D ^{t = ~} a ^E/E

_QG

^D/c

(51)

Test of Quantum Gravity ⁽²⁾ Dt = ~ a E/E _QG D/c

D ~ 2 10

²⁸

cm E

_QG

~10

¹⁹

GeV c~3 10

¹⁰

cm Dt(ms) ~ 60 DE(GeV) E

₁

E

₂

E

₁

E

₂

Dt _i =0 Dt _f =0 t=t _i

E

₁

E

₂

t=t _f

E

₁

E

₂

even at pulsars distance: • D ~ 6 10

²¹

cm Dt(ms) ~ 100 E

_QG

~10

¹⁴

GeV

(52)

another quantum gravity test

Flux absorption due to the interaction with the infrared and microwave background

g ray source

Microwave and infrared

background Earth

g g

e

⁺

e

^-

E=w

₁

J

if the center of mass energy is:

photons interactions produce electron positron pairs

(53)

Flux absorption due to the interaction with the infrared and microwave background

(2)

E=w

₁

g g

e

⁺

e

^-

E=w

₂

w

₁

and w

₁

are respectively the energies of the low and the high energies

J

gamma ray and J is their angle of incidence.

The cross section of the process gg -> e

⁺

e

^-

is:

where r

_e

is the classical radius of the electron and:

(54)

Flux absorption due to the interaction with the infrared and microwave background

⁽³⁾

g g

e

⁺

e

^-

E=w

₁

J

the ratio between the flux I(L) at a distance L from the source and the initial flux I can be written as:

I(L)/I _o =exp(-k _g L)

where k

_g

is the absorption coefficient:

that contains the cross section and the low energy photon distribution.

For the microwave spectrum:

(55)

Transparency of the Universe

100 GeV

IR

radio

2.7 k

Our galaxy Super Cluster

g g e ⁺ e ^- p g e ⁺ e ^-

p g p ⁺ p ^-

^{Z~1 ~ 2 10}

28 cm

Z~0.03 ~2 10²⁶ cm

E(eV)

Distance ( mpc )

10

¹⁰

10

¹²

10

¹⁴

10

¹⁶

10

¹⁸

10

²⁰

10

²²

10

²⁴ 10 TeV

10

^-3

10

^-2

10

^-1

10

⁰

10

¹

10

²

10

³

10

⁴

10

⁵

(Mrk521) Z~0.53, 2C279

Z~10^-6 cm

Andromeda

(700 kpc, 2.9Mly) LMC

(50 kpc, 179kly)

Virgo Cluster 60mly, 18mpc

(56)

another quantum gravity test:

the higher threshold condition introduced by quantum-gravity can be of the for

From the only hypothesis that we have seen some level of absorption

(57)

Flux absorption due to the interaction with the infrared background in H1426+428

HEGRA Coll. astro/ph 0202072

(58)

Acceleration of Cosmic Rays

EGRET GLAST simulation

Geminga

Crab

Geminga

Crab IC 443

Galactic anticenter at Eg > 100 MeV. EGRET data and GLAST one-year all-sky survey

If cosmic rays are accelerated in supernova remnants, then the high-energy gamma-ray spectral index in

supernova remnants will be equal to the cosmic-ray spectral index at the source. GLAST will have enough

angular resolution to resolve the remnant IC443 and enough sensitivity to measure its spectral index.

(59)

Expected number of isotropic extragalactic photons

detected by LAT after 5 years.

(60)

Summary of AGILE and GLAST physic items

Cosmic Diffuse Background

Origin is still a mystery for gamma rays

Is there a truly diffuse cosmological component?

Supermassive BHs and AGN

Remarkable objects that shine most brightly in gamma rays Gamma rays probe central engine

Gamma rays probe jets

GRBs

High-energy prompt and delayed emission not understood EGRET provided only a glimpse

Quantum gravity effects possible

Unidentified Sources

Mystery has been with us for > 20 years

Third EGRET Catalog includes 170 unidentified sources A new class of Galactic sources?

SNRs

Site of CR acceleration E < 10

¹⁵

eV (still unproven for nuclei!)

Should see extended sources in gammas (from p

^o

decay) to answer the question definitively

Pulsars

Gemingas only shine in gamma regime Uncover acceleration mechanisms Understand beaming

Cosmology - AGNs

Spectral roll-offs due to EBL are in GLAST range GLAST can see to z > 4

Cosmology - Dark Matter

PBHs, cosmic strings, WIMP annihilation all predicted to shine in gamma rays

From here GLAST

(61)

The GLAST Participating Institutions

Italian Team Institutions INFN - Instituto Nazionale di Fisica Nucleare: Units of Bari, Perugia, Pisa, Padova, Rome 2, Trieste Universities of Bari, Perugia, Padova, Pisa, Rome 2, Trieste, Udine

ASI - Italian Space Agency

IFC/CNR- Istituto di Fisica, Cosmica, CNR American Team Institutions

SU - Stanford University, Physics Department and EGRET group, Hanson Experimental Physics Laboratory SU-SLACStanford Linear Accelerator Center, SLAC, Particle Astrophysics group

GSFC-NASA Goddard Space Flight Center, Laboratory for High Energy Astrophysics

NRL - U. S. Naval Research Laboratory, E. O. Hulburt Center for Space Research, X-ray and gamma-ray branches UCSC- University of California at Santa Cruz, Physics Department

SSU- Sonoma State University, Department of Physics & Astronomy

UW- University of Washington , TAMUK- Texas A&M University-Kingsville

Japanese Team Institutions

University of Tokyo

ICRR - Institute for Cosmic-Ray Research

ISAS- Institute for Space and Astronautical Science

Hiroshima University

French Team Institutions

CEA/DAPNIA Commissariat à l'Energie Atomique, Département d'Astrophysique, de physique des Particules, de physique Nucliaire et de l'Instrumentation Associée, CEA, Saclay

IN2P3 Institut National de Physique Nucléaire et de Physique des Particules, IN2P3

IN2P3/LPNHE-X Laboratoire de Physique Nucléaire des Hautes Energies de l'École Polytechnique IN2P3/PCC Laboratoire de Physique Corpusculaire et Cosmologie, Collège de France

IN2P3/CENBG Centre d'études nucléaires de Bordeaux Gradignan

Swedish Team Institutions

KTHRoyal Institute of Technology

Stockholms Universitet

(62)

All sensitivities are at 5s.

Cerenkov telescopes sensitivities

(Veritas, MAGIC, Whipple, Hess, Celeste, Stacee, Hegra) are for 50 hours of

observations.

Large field of view detectors sensitivities (AGILE, GLAST, Milagro, ARGO, AMS)

are for 1 year of observation.

Sensitivity of g-ray detectors

(63)

Energy versus time for X and Gamma ray detectors

GLAST

MEGA

AGILE

SuperAGILE

AMS

(64)

Conclusion:

•AGILE will provide transient quicklook alert for all the Cerenkov telescope that will operate from 2002:

MAGIC, Whipple, Hess, Celeste, Stacee, Hegra...

• AGILE will make simultaneous observations together with the ground “all-sky monitors” like MILAGRO and ARGO.

• for the first time there will be the possibility to “fill the gap”

between space and ground !

(65)

2 ^nd Conclusions

• Neutralinos are a promising candidate for WIMP dark matter

• Neutralinos can annihilate in the galactic halo ...

• … this could give rise to high energy (> 10GeV) antiproton signature and/or gamma-ray signature.

Pamela experiment is designed to measure antiproton spectrum from 80MeV to 190GeV.

• >3 year mission large event samples

• Combination of TRD + Si tracker + imaging Si- W calo + TOF (trigger) and anticoincidence can isolate a pure sample of antiprotons.

• Engineering model currently under construction.

• Flight model due ~ June 2002.

• Launch: end 2003.

From March 2006 GLAST will search for gamma-ray signature

(66)

3 ^rd Conclusions

• GLAST will explore a good portion of the supersymmetric parameter space

• GLAST will explore the Cold and Hot Dark Matter contribution through

the IR absorption of g-ray from

extragalactic sources

(67)

INFN, Sezione di Roma 2 &

Particle Physics with

Space Detectors

Aldo Morselli

INFN, Sezione di Roma 2 &

Università di Roma Tor Vergata

To study gamma ray and cosmic ray in the MeV- GeV range you need to go outside the atmosphere

Why you want to study these items if you are a particle physicist?

• Nature of Dark Matter

(possible connection with supersymmetry)

• Quantum gravity limits

• Cosmic accelerators

Basic problem:

Cosmic Accelerators

Man-made Accelerators Cosmic Accelerators

GRB?

What is the Universe made of ?

Bright stars: 0.5%

Baryons (total): 4.4% ± 0.4%

Matter: 27% ± 4%

Cold Dark Matter: 22.6% ± 4%

Neutrinos: < 0.15%

Dark Energy: 73% ± 6%

h=0.71 + 0.04 - 0.03

W m ~0.3 W ~0.7

WMAP+SN+HST

astro-ph/0302209

astro-ph 0007333

Candidates for Galactic Dark Matter

• Massive Compact Halo Objects (MACHOs)

• Low (sub- solar) mass stars. Standard baryonic composition.

• Use gravity microlensing to study.

• Could possibly account for 25% to 50% of Galactic Dark Matter.

• Neutrinos

• Small contribution if atmospheric neutrino results are correct, since m

< 1eV.

• Large scale galactic structure hard to reconcile with neutrino dominated dark matter

• Weakly Interacting Massive Particles ( WIMPs)

• Non- Standard Model particles, ie: supersymmetric neutralinos

• Heavy (> 10GeV) neutrinos from extended gauge theories.

Neutralino WIMPs

Assume c present in the galactic halo

• c is its own antiparticle => can annihilate in galactic halo producing gamma-rays, antiprotons, positrons….

• Antimatter not produced in large quantities through standard processes (secondary production through p + p --> p + X)

• So, any extra contribution from exotic sources (c c annihilation) is an interesting signature

• ie: c c --> p + X

• Produced from (e. g.) c c --> q / g / gauge boson / Higgs boson and

Supersymmetry introduces free parameters:

In the MSSM, with Grand Unification assumptions the masses and couplings of the SUSY particles as well as their production cross sections, are entirely described once five parameters are fixed:

• M

the mass parameter of s upersymmetric partners of gauge fields (gauginos)

• the higgs mixing parameters m that appears in the neutralino and chargino mass matrices

• m

, the common mass for scalar fermions at the GUT scale

• A, the trilinear coupling in the Higgs sector

• the ratio between the two vacuum expectation values of the Higgs fields defined as:

tang b = v

/ v

= <H

> / <H

>

Experimental lower limit on the mass of the lightest neutralino assuming MSSM

(Minimal Standard Supersymmetric Model)

Lep , s = 189 GeV

M c > 50 GeV ( )

(3

)

EGRET data & Susy models

~2 degrees around the galactic center

EGRET data

Annihilation channel b-bbar M c =50 GeV

background model(Galprop)

WIMP annihilation (DarkSusy)

Total Contribution

Main Diagrams for Neutralino Annihilation

gauge bosons

fermions

Light fermion pairs suppressed due to Pauli Principle (neutralinos are Majorana particles and fermions fi Pauli Principle at zero momentum fi p wave fi µ fermion mass !)

Low values of tan b (<3.8 excluded by electroweak data (g2, LEP Higgs Limit and BR(bôsg)

At larger values of tan b , bbar

W _m ^~0.3 W ^~0.7

• ^M

• ^m

tang b ^{= v}

^{/ v}

^{= <H}

M _c > 50 GeV ⁽ ⁾