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3rd Presentation of Prof. 3rd Presentation of Prof. Cho’s ClassCho’s Class
Hossain AhmedHossain Ahmed
25.11.200325.11.2003
AMS ExperimentAMS Experiment
Physics from 1900’s to 1928
It was the beginning of the 20th century, an exciting time when the very foundations of physics were shaken by the appearance of two important new theories: relativity and quantum mechanics.
--- 1905 Einstein unveiled his theory of Special Relativity, explaining the relationship between space and time, and between energy and mass in his famous equation E=mc2
---Max Planck ---each light wave must come in a little packet, which he called a "quantum": this way light was not just a wave or just a particle, but a bit of both.
--- By the 1920s, physicists were trying to apply the same concept to the atom and its constituents, and by the end of the decade Erwin Schrodinger and Werner Heisenberg had invented the new quantum theory of physics.
--- that quantum theory was not relativistic
--- 1928, Paul Dirac solved the problem--- Nobel Prize in 1933--- also posed another problem: just as the equation x2=4 can have two possible solutions (x=2 OR x=-2), so Dirac's equation could have two solutions, one for an electron with positive energy, and one for an electron with negative energy ---in classical physics (and common sense!), the energy of a particle must always be a positive number!
0,2
42222
pmcE
cmcpE
We see that the eigenvalues can be positive or negative. A plot of the energy levels is shown below
Concept of anti-matter!!
In his Nobel Lecture, Dirac speculated on the existence of a completely new Universe made out of antimatter!
--- In 1932 Carl Anderson--- anti-electrons or "positron” --- cloud chamber (1936 N.P)
--- In 1930, Ernest Lawrence --- cyclotron--- the accelerator era had begun, and with it the new science of "High Energy Physics" was born (1939 N.P)
--- In October 1955--- Segre' and his group of collaborators---- Negative Proton or anti-proton --- (1959 N.P)
--- Only a year later, a second team working at the Bevatron (B. Cork, O. Piccione, W. Wenzel and G. Lambertson) announced the discovery of the antineutron.
if (proton + neutron = nucleus) with electron = atom
then ( anti-proton + anti-neutron = anti-nucleus) with anti-electron = anti-atom
else laws of physics = = = = 0 (??)
if atom = basic unit of matter
then anti-atom >= basic unit of anti-matter
else Physics = no body’s believe !!
Anti nuclei era:
But are matter and antimatter exactly equal and opposite, or symmetric, as Dirac had
implied? The next important step was to test this symmetry ! --- In the late 1950s, the amount of antimatter in our galaxy was calculated to be less then one part in a hundred million.
---Over the past twenty years, scientists have tried to take their instruments as high as possible in the atmosphere
A world-wide collaboration of physicists, lead by Nobel prize laureate Prof. Samuel Ting of MIT, decided to build the 'Alpha Magnetic Spectrometer', or AMS.
---AMS is a high energy particle detector which will try to detect the passage of such very small amounts of antimatter, while orbiting at an altitude of a few hundred kilometers(about 400km) above the atmosphere.
Will AMS only study the anti-matter ?
--- No!
The AMS Experiment & its The AMS Experiment & its Physics Motivation Physics Motivation
AMS is the the first large magnetic spectrometer in space with the biggest silicon system ever.
The AMS Physics The AMS Physics Motivation Motivation
• Stydy of cosmic ray origin, age and propagation in the galaxy
– By measuring precisely the abandence of H, 2H, 4He, 3He, 9Be/10Be, B/C etc isotopes
• Search for signal of super-symmetric Dark Matter
• Search for Antimatter
– primary goal of AMS, up to |Z|=6
• High energy photons (> 1 GeV)
– complementary to satellite and ground telescopes
A spectrometer in the space for
a long time is the best way to achieve the goal.
A spectrometer in the space for
a long time is the best way to achieve the goal.
So AMS will measure the ‘fingerprints’ of astrophysical objects in high-energy particles at Cosmic Rays.
Antimatter .. Cold dark matter .. Strangelets .. Microquasars .. Primordial black holes .. Earth's particle environment
The AMS –01 DetectorThe AMS –01 Detector
Precursor flight (STS-91, 2 –12 June 1998) of 10 days on board at the Space Shuttle :
Sub detectors:
a) The Magnet
Nd-Fe-B
b) The silicon Tracker
300 m thick double-sided micro strip sensors of area 40.10 x 72.04 mm2
c) TOF System
14 counters (Bicron BC408 plastic scintillator) 1 cm
thick covering a roughly circular area of 1.6m2.d) The anticoincidence system
16 plastic scintillator counters (of the same material as the TOF ones)
e) The Threshold Cerenkov Counter
consists of two layer of 8 x 10 (upper) and 8 x 11 (lower) aerogel cells with refractive index n = 1. 035
Result of AMS –Result of AMS –01 01
altitudes between 320 and 390 km
in the rigidity range 1- 140 GeV was performed but No antihelium nuclei were detected at any rigidity. An upper limit on the flux ratio of anti-helium to helium of <1.1 x 10-6 was obtained.
Transition Radiation Detector
Time-of-flight counters
Super-conducting Magnet
Silicon Tracker
Ring Imaging Cerenkov Detector
Electromagnetic Calorimeter
Anti-coincidence veto counter
Unique Support Structure +Onboard electronics + Thermal control system
The AMS –02 Sub-The AMS –02 Sub-detectorsdetectors
Properties of Sub-detectors in a energy range
CR composition
Cosmic Rays composition ~88% proton ~ 9% He nuclei ~1% Z > 2 nuclei ~ 2% electrons, positron, gamma, neutrino etc.
The AMS –02 TRDThe AMS –02 TRD
. Transition radiation is a radiation in the X-ray region. It depends strongly on the relativistic factor γ. where time of flight methods or detection of Cherenkov radiation no longer work
The AMS –02 TOFThe AMS –02 TOF
a particle with velocity v =β c takes a time t = l / v to go along the path l = L / cosθ between upper and lower
TOF planes (L is their distance and θ is the trajectory colatitude angle). Hence, the time of flight is:
t = L/ β c cosθ
upper planes
lower planes
The time of flight system has 4 planes made of 1 cm thick plastic scintillator paddles of different shapes:
Importance:
a) Trigering system
b) Velocity measurement
c) Particle directions
The AMS –02 EcalThe AMS –02 Ecal
Some Properties of e/m & hadronic shower
Transverse profile of shower in the unit of Rm
Lo
ng
itud
ina
l pro
file of e/m
sho
wer
in th
e un
it of X0
Simulation of an electromagnetic shower of 16GeV on AMS-02 EM calorimeter :
Z
MeVEE c
800~
Signal from PMT’s (Raw Data) AMS Software Reconstructed data
Energy Deposition, Shower Direction, Shower entry & Exit point, Energy leak, altitude of Shower max etc.
Particle Energy
