The AMS Project - Argentina.gob.arscoccola/iguazu/NR/17_NR_17_STEUER.pdf · The magnet provided the...

AMS, M.Steuer, NR-17, SLAFNAP VI/1

The AMS ProjectNuclei in Cosmic Rays - Results from AMS01 and

Potential of AMS02Manfred Steuer, MIT and the AMS Collaboration

VI Latin American Symposium on Nuclear Physics and ApplicationsIguazu, Argentina, 3 - 7 October 2005


OUTLINE

AbstractThe Purpose of the AMS ExperimentPhysics Results of the AMS01 Test Flight in June 1998The Worldwide AMS CollaborationDetector Elements and Status of AMS02Timeline of AMS02

Many thanks to my colleagues in the AMS data acquisition and analysis groups at CERN

Visit AMS at http://ams.cern.ch/


The Alpha Magnetic Spectrometer (AMS) on the International Space Station, scheduled for a three years flight starting in 2007, will be able to identify nuclei both in the earth's radiation belt and in primary cosmic rays. Charge determination allows searching for anti-nuclei. A ten days test flight (AMS01) in 1998 on the space shuttle Discovery (STS-91) in a 51.7o orbit at altitudes between 320 and 390 km yielded a vast amount of data on the fluxes of charged particles. The major detector elements of AMS01 were a permanent magnet with an analyzing power B*L2 of 0.14 Tm2, a six layer, double sided silicon tracker, time of flight hodoscopes, an aerogel threshold Cerenkov counter and anti-coincidence counters. A total of 2.8 x 106 helium nuclei were observed in the rigidity range 1 to 140 GeV. No antihelium nuclei were detected at any rigidity. The upper limit on the flux ratio of antihelium to helium was determined as $1.1 x 10-6. Below the geomagnetic cutoff a second helium spectrum is observed and more than 90% of the helium was identified as 3He. A search for charge two anomalous nuclei was conducted, and one candidate event, which corresponds to a flux of 10-4 m-2 sr-1 sec-1, was found. The candidate has a Z/A ratio of 0.11 and a kinetic energy of 2.1 GeV. The estimated background from ordinary nuclei is one per mille.For the forthcoming AMS02 flight, several major upgrades have been done, the most prominent being the replacement of the permanent by a superconducting magnet, the first of its kind to be used in space. This, together with the much longer data taking period, allows to greatly extend the sensitive region of the spectrometer. The addition of a transition radiation detector, a ring imaging Cerenkov counter and an electromagnetic calorimeter enables a diversification of the physics program of AMS02.

Abstract


Cosmic rays

AMS will be the 1st experiment to accurately measure the charged cosmic rays outside the magnetosphere. 20 years on ISS3 years with magnetic field


The purpose of the AMS experiment is to perform accurate, high statistics measurements of energetic (0.2 GeV/n to ~ 2 TeV/n) charged

cosmic rays and high energy gamma rays.1. Antimatter2. Dark Matter3. Strangelets4. Origin of Cosmic Rays5. …

The Big Bang The Big Bang requires matter and antimatter requires matter and antimatter to be equally abundant to be equally abundant at the beginningat the beginning


Anti universe ?Anti universe ?UniverseUniverse

HeHeCC

HeHeCC

Question

y96222_03_2.ppt

Cosmic antimatter cannot be detected on earth because matter andCosmic antimatter cannot be detected on earth because matter andantimatter will annihilate each other in the atmosphereantimatter will annihilate each other in the atmosphere


The physics of antimatter in the universe is based on:the existence of a strong Time Reversal Violationthe existence of Baryon Number Violation (proton decay)Grand Unified TheoryElectroweak Theory

This is the main research topic for the current and next generation of accelerators world wide

If no antimatter is found => there is no antimatter to the edge If no antimatter is found => there is no antimatter to the edge (1000 (1000 MpcMpc) of universe.) of universe.

AntimatterAntimatter MatterMatter

the Foundations of Modern Physics

Nuclear charge

2x109 nuclei

Num

ber o

f eve

nts

Dark matterThere are many theoretical suggestions that SUSY particles (χ)are at least part of the Dark matter.

y97089_2a.ppt

90% of the Universe is not observable90% of the Universe is not observable~ 20% is made of Dark Matter~ 20% is made of Dark Matter

What is Dark Matter ?What is Dark Matter ?

AMS, M.Steuer, NR-17, SLAFNAP VI/9y01K22ge.ppt

The ratio 10Be / 9Be determines

One of the most important measurements in cosmic ray physics

Be 9 stableBe10 Half life 1.51 million years

i) the cosmic ray confinementtime in the galaxy, and

ii) the mean density ofinterstellar materialtraversed by cosmic rays.


The Purpose of the AMS Experiment

• The existence (or absence) of antimatter nuclei in space is closely connected with the foundation of the theories of elementary particle physics, CP-violation, baryon number nonconservation, Grand Unified Theory (GUT), etc.

• Balloon-based cosmic ray searches for antinuclei at altitudes up to 40 km have been carried out for more than 20 years; all such searches have been negative.

• The Alpha Magnetic Spectrometer (AMS) is scheduled for a particle physics program on the International Space Station. This program will search for antinuclei using an accurate, large acceptance magnetic spectrometer. In addition searches for supersymmetric dark matter, composition, origin and transport mechanisms of cosmic rays will be carried out.

• The AMS flight on the space shuttle Discovery (STS-91) in June 1998 was primarily a test flight to verify the detector's performance under space flight conditions.


Matter and antimatterhave opposite electric charges;

we need a magnetic detector to measure the charge of antimatter.

HeHe


Alpha Magnetic Spectrometer - AMS-01First flight, STS-91, 2 June 1998 (10 days)

y99163_04c.ppt

TOFTOFScintillatorsScintillators

TrackerTracker

MagnetMagnet

PM’sPM’s

AerogelAerogel CerenkovCerenkov CounterCounter

Detector Elements• Permanent Magnet• Silicon Tracker• TOF Scintillator Hodoscopes• Scintillator Anti Counters• Threshold Cerenkov Counter• Electronics and DAQ• Payload General Support Computer

Average acceptance 0.15 m2. sr(angle and location dependent)

Low Energy Particle Shield

Ant

i Cou

nter

Computers

Electronics

Scintillators

Honeycomb


The AMS01 Magnet

The magnet provided the analyzing power of the spectrometer.

• Made of 1.9 tons of Nd-Fe-B in the shape of a cylindrical shell.

• Of inner diameter 1115 mm and length 800 mm.

• Nd-Fe-B magnetized to 46 MGOe with the direction varying to provide a dipole field in the x direction,perpendicular to the cylinder axis.

• At the center the magnetic field was 0.15 Tesla and the analyzing power, BL2 was 0.14 Tm2

AMS Coordinate system


After the shuttle had attained orbit, data collection commenced on 3 June 1998 and continued over the next nine daysfor a total of 184 hours.A total of 100 million triggers were recorded. Around 12% of Physics Data were sent via slow links to various NASA/USAF ground stations and delivered in almost real time. During data taking the shuttle altitude varied from 320 to 390 km and the latitude range was between ±51.7o.Before rendezvous with the MIR space station the attitude of the shuttle was maintained to keep the z-axis of AMS pointed within 450 of the zenith.While docked, the attitude was constrained by MIR requirements and varied substantially. After undocking the pointing was maintained within 1, 20 and then 40 degrees of the zenith. Shortly before descent the shuttle turned overand the pointing was towards the nadir.

AMS01 Flight in June 1998


Events were triggered by the coincidence of signals in all four TOF planes consistent with the passage of a charged particle through the active tracker volume. Triggers with a coincident signal from the ACC were vetoed.

The AMS01 Trigger

DAQ Switch

S2

Tracker

S4

CoincLevel-1

ORPlane Discr

PMT+HV

Trigger

ComputerLevel-3

Earth

Level-1

Level-2

ADC

DAQTrack

PMT+HV TDC,ADC

ReadoutS1

S3

LatchHitEncode

Level-2Deflection

(1100/plane)

(3) (6) (8)

(3) (3) (3)

(3)

(3)

(4) (3) (4-8)

(3)

(3)

(3)

(3) (3)

(3)

(5)

Processor

The detector performance as well as temperature and magnetic field were monitored continuously.


AMS01 Physics Results

• Event Reconstruction• Search for Nuclear Anti-Matter

– Antihelium in primary cosmic rays.– Helium near the earth.

• Systematic Measurement of Proton Spectra – Protons in primary cosmic rays.– Protons near the earth.

• Measurement of e+ and e- Spectra• Search for Charge Two Anomalously Heavy Nuclei


Event Reconstruction•The sign of the particle charge was derived from the deflection in the rigidity fit and the particle direction.

•The particle mass was derived from |Z|R and ß

•Measurement of the particle rigidity, R=pc/|Z|e (GV), from the deflection of the trajectory measured by the tracker in the magnetic field. Hits in at least four tracker planes were required and the fitting was performed with two different algorithms, the results of which were required to agree.

•Measurement of the particle velocity, ß, and direction, , was obtained from the TOF, where signifies a downward going particle in the AMS coordinate system.

•Determination of the magnitude of the particle charge, |Z|, from the measurements of energy losses in the TOF counters and tracker planes (corrected for ß).

ˆ z = ±1ˆ z = −1


Search for Anti-Helium in Primary Cosmic Rays

We obtain a total of 2.86 x 106 He events up to 140GV rigidity.

• We found no Anti-He event at any rigidity.

• Since no Anti-He nuclei were observed,we can only establish an upper limit on their flux.

• If the incident Anti-He spectrum is assumed to have the same shape as the He spectrum over the range 1<R<140 GV, then one obtains at the 95% C.L. a Anti-He/He flux limit of

< 1.1 x 10-6

NHe

Measured rigidity times the charge sign for selected |Z|=2 events


He Spectra

A fit to the primary He spectrum shows similarity to the primary proton spectrum. This points to the same source for both particles.

In the range 20 < R < 200 GV, the data are best described by a power law in rigidity

Φ = Φo x R-γ

Helium flux spectra for zenith pointing data, separated according to ΘM

γ = 2.740 ± 0.010(stat) ± 0.016(sys)Φo= 2.52 ± 0.09(stat) ± 0.13(sys)

AMS, M.Steuer, NR-17, SLAFNAP VI/21y99089_04a.ppt

“Helium in Near Earth Orbit”Helium spectrum (Mass of He4 = 3.7 GeV; He3 = 2.8 GeV)

He4

80

60

40

20

0

102

10

1-0.8 -0.4 0 0.4 0.8

10

20

40

30

Ener

gy/2

0 1 2 3 4 5 6

5 10

Even

ts

Even

ts

(GeV)

Mass (GeV)Physics Letters B vol.494 (3-4) (2000) p.193-202.

AMSAMS--01 results were not predicted by any cosmic ray model01 results were not predicted by any cosmic ray model

ΘM


Nearly all these protons were found to and downward fluxes agree within 1%. 70% of these protons have flight-time >0.3 sec and

originate in the atmosphere. the upward

strongly localized points of origin in geomagnetic coordinates.


-80

-60

-40

-20

0

20

40

60

80

-80

-60

-40

-20

0

20

40

60

80

-150 -100 -50 0 50 100 150

a) e-

b) e+

Longitude

Lati

tud

e

B A

A

B

Ori

gin

Latitu

de (

degre

es)

-80

-60

-40

-20

0

20

40

60

80

-150 -100 -50 0 50 100 150

Origin Longitude (degrees)

Long Lived p Detected at ΘM < 0.3 rad

Origin of long-lived protons and long-lived electrons and positrons in geomagnetic coordinates.

flight-time > 0.3sec ΘM < 0.3, P <3 GeV

Long Lived p Detected at ΘM < 0.3 Rad and Long Lived e- and e+ Measured at p < 3 GeV

AMS, M.Steuer, NR-17, SLAFNAP VI/24y2K208_04Pap40F9.ppt

AMS paper: ”Cosmic Protons" Physics Letters B, Vol.490 (2000) p.27-35

Mod

elM

odel

Primary proton spectrum

Posi

tron

s / E

lect

rons

N (e

+/ e

– )AMS paper: “Leptons in Near Earth Orbit” AMS paper: “Leptons in Near Earth Orbit” Physics Letters B 484 (2000) p.10-22

Geomagnetic Latitude ΘM Deg


Strangelet candidate from AMS-01

Background probability < 10-3

Total He Sample 204365

AMS-01

Z/A

Observed 5 June 1998 11:13:16 UTCLat/Long= -44.38°/+23.70°, Local Cutoff 1.95±0.1 GV, Angle= 77.5° from local zenith

Front view Side view

β 1

Ampli

tude =

> Z,

β2

Rigidity = 4.31 ± 0.38 GVCharge Z = 2 β1 = β2 = 0.462 ± 0.005 Mass = 16.45±0.15 GeV/c2

Z/A = 0.114 ± 0.01Flux (1.5 < EK < 10 GeV) = 5x10-5 (m2 sr sec)-1

Can

dida

teZ/A ratio ≈ β x γ x mproton / Rigidity

distinguishes between anomalously heavy and ordinary He event


Strange Quark Matter – “Strangelets”

Quarks = u, d, s, c, b, t.

Matter is made of protons, p=(u,u,d), & neutrons, n=(u,d,d), Z/A(nuclei) ~ 0.5

Strangelets are a single “super nucleon” with many (many) u, d & s quarks:

• Low charge to mass: Z/A(Strangelet) < 0.12

• Stable for all masses above A > Amin~10 with no upper limit

•“Neutron” stars may actually be composed of one big strangelet

Searches

with terrestrial samples – low sensitivity.

with lunar samples – limited sensitivity.

in accelerators – cannot be produced at an observable rate.

in space – candidates…

Carbon Nucleus

Strangelet

26

uuddss

ssdd

dd ss

ssuudd

uudduuuudddd

ssuussuuuudd

dd dd dddd dd

uuuu

uuuu

ssuu ss

ssss

dddd uuuu

uudduu uudd

dddd uu

uu uudd

dddd uu dddd uu dddd uudddd uu

uu uudd uu uudd

uu uudd


Search for Antihelium in Cosmic Rays J. Alcaraz et al, The AMS Collaboration Physics Letters B 461 1999 387–396 (2 September 1999)

Protons in Near Earth OrbitJ. Alcaraz et al, The AMS Collaboration Physics Letters B 472 2000 215–226 (13 January 2000)

Leptons in Near Earth OrbitJ. Alcaraz et al, The AMS CollaborationPhys. Lett. B484 2000 10-22 (27 June 2000)

Cosmic ProtonsJ. Alcaraz et al, The AMS CollaborationPhys. Lett. B490 2000 27-35 (28 September 2000)

Helium in Near Earth OrbitJ. Alcaraz et al, The AMS CollaborationPhys. Lett. B494 2000 193-202 (30 Nov 2000)

The Alpha Magnetic Spectrometer (AMS) on the International Space Station, Part I, Results from the test flight on the Space ShuttleJ. Alcaraz et al, The AMS CollaborationPhysics Reports, vol. 366/6 331-405 (Aug 2002)

AMS01 Physics Publications


Atlantis departing from Mir during the STS-71 Flight


AMSAMS

`

AMS02 on the International Space StationStudy of Antimatter, Matter, Missing Matter


AMS is a truly Worldwide International Collaboration

• 3 Continents [ 3 Continents ]• 16 Countries [ 11 Countries ]• 57 Institutions [ 37 Institutions ]

[AMS02] [AMS01]• NASA - DOE Agreement• CERN Recognized Experiment (RE1)• International Logistics most easily realized at CERN

Principal Investigator / Spokesperson: S.C.C. Ting

International AMS02 CollaborationInternational AMS02 Collaboration

USAA&M FLORIDA UNIV.JOHNS HOPKINS UNIV.MIT - CAMBRIDGENASA GODDARD SPACE FLIGHT CENTERNASA JOHNSON SPACE CENTERUNIV. OF MARYLAND-DEPRT OF PHYSICSUNIV. OF MARYLAND-E.W.S. S.CENTERYALE UNIV. - NEW HAVEN

MEXICOUNAM

DENMARKUNIV. OF AARHUS

FINLANDHELSINKI UNIV.UNIV. OF TURKU

FRANCEGAM MONTPELLIERLAPP ANNECYLPSC GRENOBLE

GERMANYRWTH-IMAX-PLANK INST.UNIV. OF KARLSRUHE

ITALYASICARSO TRIESTEIROE FLORENCEINFN & UNIV. OF BOLOGNAINFN & UNIV. OF MILANOINFN & UNIV. OF PERUGIAINFN & UNIV. OF PISAINFN & UNIV. OF ROMAINFN & UNIV. OF SIENA

NETHERLANDSESA-ESTECNIKHEFNLR

ROMANIAISSUNIV. OF BUCHAREST

RUSSIAI.K.I.ITEPKURCHATOV INST.MOSCOW STATE UNIV.

SPAINCIEMAT - MADRIDI.A.C. CANARIAS.

SWITZERLANDETH-ZURICHUNIV. OF GENEVA

CHINA BISEE (Beijing)IEE (Beijing)IHEP (Beijing)SJTU (Shanghai)SEU (Nanjing)SYSU (Guangzhou)SDU (Jinan)

KOREA

EWHAKYUNGPOOK NAT.UNIV.

Y96673-05_1Commitment

PORTUGAL

LAB. OF INSTRUM. LISBON

ACAD. SINICA (Taiwan)CSIST (Taiwan)NCU (Chung Li)NCKU (Tainan)

NCTU (Hsinchu)NSPO (Hsinchu)

TAIWAN

Status January 1, 20053 Continents, 16 Countries, 57 Institutions


The AMS detector has been under construction for 10 years.The AMS detector has been under construction for 10 years.Final ESA thermal vacuum test of the entire detector in Final ESA thermal vacuum test of the entire detector in 2006.2006.

ECAL


8.600

B = 0.5 Gauss

STEP ONE: A Permanent Magnet to fly on STS-91

1- Stable: no influence from earth magnetic field

2- Safety for the astronauts:minimum field leakage out of the magnet

3- Low weight: no iron

STEP TWO: A Superconducting Magnet for ISS with the same field arrangement

AMS-02

There has never been a large superconducting magnet in spacedue to the extremely difficult technical challenges

AMS-01

AMS, M.Steuer, NR-17, SLAFNAP VI/34Y04K615 Harrison


TRD(5248 channels)

TOF

Tracker(200000 channels)

TOFRICH

(10880 channels)

ECAL(1300 ch.

Supe

rcon

duct

ing

Mag

net

2500

L S

F H

eliu

m

Transition Radiation Detector (TRD)Transition Radiation Detector (TRD)

One

of

20 la

yers

Radiator

6 m

m

Identifies electrons and positrons from all other particlesIdentifies electrons and positrons from all other particles

V=0.99999C

20 m

m

5248 tubesL(max) = 1.8m

Xe/CO2

All Flight Hardware Modules produced. Assembly complete in 2005All Flight Hardware Modules produced. Assembly complete in 2005..


V=0.99999C

Distinguish electrons from all other particlesDistinguish electrons from all other particles

y04K513_05 y03K193_03_ca.ppt

Silicon Tracker

8 planes 6.6 m2: Largest Silicon Detector

with 10 μm accuracy

TRD(5248 channels)

TOF


TOFRICH

(10880 channels)

ECAL(1300 ch.

Supe

rcon

duct

ing

Mag

net

2500

L S

F H

eliu

m

Production completed. Test results from accelerator.

AMS, M.Steuer, NR-17, SLAFNAP VI/39y03K193_03_caUS.ppt

Silicon TrackerP-dopedn-doped

300 μm

Center of chargeDistribution

Accurate < 10μm

Flat arrayof strip Diodes

25μm

Reverse voltageDepletes junction

⇒ no current

Ionizing particle Creates current of~ 3x104 electrons

AMS02: 8 planes 6.6 m2

Largest Silicon Detector with 10 μm accuracy


Silicon Tracker Silicon Tracker All 8 planes, 300,000 channels have been producedAll 8 planes, 300,000 channels have been produced

Tracker on large 3DTracker on large 3D

measuring machinemeasuring machine

Coordinator: Coordinator: R.BattistonR.Battiston


TRD(5248 channels)

TOF


TOFRICH

(10880 channels)

ECAL(1300 ch.

Supe

rcon

duct

ing

Mag

net

2500

L S

F H

eliu

m

Ring Imaging Cerenkov Counter (RICH)Ring Imaging Cerenkov Counter (RICH)

Reflector

Photon Detection

Radiator

10,880 Photon detectors

Reflector

Particle (Z,v)

γθθ ∝ velocity v Li C OHe Ca

Test results at 158 GeV/n

Light (γ) intensity ∝ Z2


Ring Imaging Ring Imaging CerenkovCerenkov Counter (RICH)Counter (RICH)Coordinator: G. Laurenti

Test beam resultsat 158 GeV/n


Angular resolution: by 11,0004mm x 4mm photomultipliers

The Ring Imaging Cerenkov Counter (RICH)

Intensity => Nuclear charge Z2

To provide: ΔV/V = 1/103

y01K233ec234c

P = mVP: by trajectory in the magnetV: by angle in RICHZ2: by intensity in RICH and Tracker

P

AMS, M.Steuer, NR-17, SLAFNAP VI/44y01K137d241a

RICH Test Beam Results E = 158 RICH Test Beam Results E = 158 GeV/nGeV/n

Charge measuredup to Z = 26 (Fe)

Velocity resolution = 0.1%

v/c Z


J.P. Vialle F. Cervelli H.S. Chen3D

Sampling

Shower⇒

e± energy

AMS-02 Calorimeter

y01K525_6bEcalLscap.ppt

Measuring energy of electrons and γ rays

Lead

Fibers(ø=1mm)PM onBoth End

LAPPAnnecy

INFNPisa

IHEPBeijing

Coordinator: F. Cervelli


AMSAMS--02 Electronics on the ISS02 Electronics on the ISS

The AMS electronics is based on Accelerator physics technologies.It is ~ 10 times faster than commercial space electronics.

Radiation tests with heavy ions at GSI, Germany

~ 7 Gbit/sec 2 Mbit/sec

Radiation tests with heavy-ions at Catania

600 micro-processorsTrigger Rate

2000 Hz

Average Data Size3.5 Mbit

Coordinator: Coordinator: M.CapellM.Capell

AMS, M.Steuer, NR-17, SLAFNAP VI/48y2K269

Integration of AMS02 individual detector components

at CERN in 2006

Beam Test / Calibration at CERN in 2006

Integration SequenceUpper USS

CryomagnetACC SystemTracker TCSLower TOF

TrackerUpper TOF

TRDLower USS

RICHECAL


Integration of AMS02 individual detector components at CERN in

2006

Thermal vacuum test at ESA, Holland

After Integration and Beam Test at CERN transport to Holland for

TVT and EMI

Afterwards via Cargo Flight to KSC, Florida

At KSC 6 months flight preparation

Shuttle Flight to ISS

3 years Physics with superconducting Magnet On

> 15 years Physics without magnetic field

AMS, M.Steuer, NR-17, SLAFNAP VI/50y04K419_04a.ppt

Up to 20 years on ISS for understanding space environment

A permanent cosmic radiation monitor A permanent cosmic radiation monitor for all nuclei, for all energy ranges.for all nuclei, for all energy ranges.

TRD

TOF

RICH

VacuumCase

Tracker

MA

GN

ET

He

Vess

el

Accelerator measurements of AMSAccelerator measurements of AMS--02 detector02 detector

Energy (GeV/n)

As function of timeAs function of timeandand

energy for each nucleienergy for each nuclei

Oxygen flux

Time

Energy

The AMS Project - Argentina.gob.arscoccola/iguazu/NR/17_NR_17_STEUER.pdf · The magnet provided the...

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