slide1
Download
Skip this Video
Download Presentation
La missione PAMELA: primi risultati scientifici

Loading in 2 Seconds...

play fullscreen
1 / 63

La missione PAMELA: primi risultati scientifici - PowerPoint PPT Presentation


  • 129 Views
  • Uploaded on

XCIV Congresso Nazionale Societ à Italiana di Fisica Genova 22-27 Settembre, 2008. La missione PAMELA: primi risultati scientifici. Paolo Papini INFN – Firenze a nome della collaborazione PAMELA. Italy :. CNR, Florence. Bari. Florence. Frascati. Naples. Rome. Trieste. Russia :.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' La missione PAMELA: primi risultati scientifici' - lotta


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

XCIV Congresso Nazionale

Società Italiana di Fisica

Genova 22-27 Settembre, 2008

La missione PAMELA:primi risultati scientifici

Paolo Papini

INFN – Firenze

a nome della collaborazione PAMELA

slide2

Italy:

CNR, Florence

Bari

Florence

Frascati

Naples

Rome

Trieste

Russia:

Moscow

St. Petersburg

Germany:

Sweden:

Siegen

KTH, Stockholm

Tha PAMELA collaboration

slide3

PAMELA as a Space Observatory at 1 AUPayload forAntimatterMatterExploration and Light Nuclei Astrophysics

  • Search for dark matter annihilation
  • Search for antihelium (primordial antimatter)‏
  • Search for new Matter in the Universe (Strangelets?)
  • Study of cosmic-ray propagation
  • Study of solar physics and solar modulation
  • Study of terrestrial magnetosphere
  • Study of high energy electron spectrum (local sources?)
pamela prehistory
PAMELA prehistory

Astromag/WiZard project (PAMELA precursor) on board of the Space Station FreedomCANCELED

Balloon-borne experiments: MASS-89,91 TS-93 CAPRICE-94,97,98

Space experiments*: NINA-1,2 SILEYE-1,2,3 ALTEA

(*study of low energy nuclei and space radiation environment)

C 98

C 94

C 97

M 91

M 89

TS 93

NINA-2

NINA-1

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

- - - - X

SILEYE-3

SILEYE-1

SILEYE-2

ASTROMAG

ALTEA

pamela history
PAMELA history

1996: PAMELA proposal

22.12.1998: agreement between RSA (Russian Space Agency) and INFN to build and launch PAMELA.

Three models required by the RSA:

Mass-Dimensional and Thermal Model (MDTM)

Technological Model (TM)

Flight Model (FM)

 Starts PAMELA construction

2001: change of the satellite complete redefinition of mechanics

2006: flight!!!

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

pamela nominal capabilities
PAMELA nominal capabilities

Energy range

Antiprotons 80 MeV - 150 GeV

Positrons50 MeV – 270 GeV

Electronsup to 400 GeV

Protons up to 700 GeV

Electrons+positronsup to 2 TeV (from calorimeter)

Light Nuclei up to 200 GeV/n He/Be/C

AntiNuclei search

  • Simultaneous measurement of many cosmic-ray species
  • New energy range
  • Unprecedented statistics
pamela detectors
PAMELA detectors

Main requirements  high-sensitivity antiparticle identification and precise momentum measure

+ -

Time-Of-Flight

plastic scintillators + PMT:

  • Trigger
  • Albedo rejection;
  • Mass identification up to 1 GeV;

- Charge identification from dE/dX.

Electromagnetic calorimeter

W/Si sampling (16.3 X0, 0.6 λI)

  • Discrimination e+ / p, anti-p / e-

(shower topology)

  • Direct E measurement for e-

Neutron detector

plastic scintillators + PMT:

  • High-energy e/h discrimination

GF: 21.5 cm2 sr Mass: 470 kg

Size: 130x70x70 cm3

Power Budget: 360W

Spectrometer

microstrip silicon tracking system+ permanent magnet

It provides:

- Magnetic rigidity R = pc/Ze

  • Charge sign
  • Charge value from dE/dx
slide9

PAMELA milestones

  • Launch from Baikonur: June 15th 2006, 0800 UTC.
  • Power On: June 21st 2006, 0300 UTC.
  • Detectors operated as expected after launch
  • PAMELA in continuous data-taking mode since commissioning phase ended on July 11th 2006
  • As of ~ now:
    • more than 2 years of data taking (~73% live-time)
    • ~10 TByte of raw data downlinked
    • >109 triggers recorded and under analysis
resurs dk1 satellite orbit
Resurs-DK1 satellite + orbit
  • Resurs-DK1: multi-spectral imaging of earth’s surface
  • PAMELA mounted inside a pressurized container
  • Lifetime >3 years (assisted)
  • Data transmitted to NTsOMZ, Moscow via high-speed radio downlink. ~16 GB per day
  • Quasi-polar and elliptical orbit (70.0°, 350 km - 600 km)
  • Traverses the South Atlantic Anomaly
  • Crosses the outer (electron) Van Allen belt at south pole

PAMELA

Resurs-DK1

Mass: 6.7 tonnes

Height: 7.4 m

Solar array area: 36 m2

350 km

70o

SAA

610 km

~90 mins

slide11

Analysis of a PAMELA orbit

S1

S2

S3

SAA

NP SP

EQ EQ

orbit 3752

orbit 3753

95 min

orbit 3751

Low energy particles stops inside the apparatus

 Counting rates: S1>S2>S3

Outer radiation belt

Download @orbit 3754 – 15/02/2007 07:35:00 MWT

S1

S2

S3

Inner radiation belt

(SAA)

Ratemeters

Independent from trigger

principle of operation
Principle of operation

Track reconstruction

  • Measured @ground with protons of known momentum
    •  MDR~1TV
  • Cross-check in flight with protons (alignment) and electrons (energy from calorimeter)

Iterative c2 minimization as a function of track state-vector components a

Magnetic deflection

|η| = 1/R

R = pc/Ze magnetic rigidity

sR/R = sh/h

Maximum Detectable Rigidity (MDR)

def: @ R=MDR sR/R=1

MDR = 1/sh

principle of operation1
Principle of operation

track average

4He

B,C

3He

Be

d

(saturation)

p

Li

1st plane

Z measurement

Bethe Bloch

ionization energy-loss of heavy (M>>me) charged particles

principle of operation2
Principle of operation

Velocity measurement

  • Particle identification @ low energy
  • Identify albedo (up-ward going particles b < 0 )
  •  NB! They mimic antimatter!
principle of operation3
Principle of operation

Electron/hadron separation

  • Interaction topology
  • e/h separation
  • Energy measurement of electrons and positrons
  • (~full shower containment)

hadron (19GV)

electron (17GV)

+ NEUTRONS!!

slide16

Flight data:

0.171 GV positron

Flight data:

0.169 GV electron

slide17

32.3 GV

positron

slide18

36 GeV/c

interacting proton

slide19

Flight data: 0.632 GeV/c

antiproton annihilation

slide20

Flight data: 0.763 GeV/c

antiproton annihilation

slide22

NB! still large discrepancies among different primary flux measurements

Galactic H spectra

Preliminary!!

Very high statistics over a wide energy range

 Precise measurement of spectral shape

 Possibility to study time variations and transient phenomena

(statistical errors only)

Power-law fit: ~ E-g

g~ 2.76 for Z=1

  • Proton of primary origin
  • Diffusive shock-wave acceleration in SNRs
  • Local spectrum:
  • injection spectrum  galactic propagation
  • Local primary spectral shape:
  • study of particle acceleration mechanism

LBM ->

slide23

Geomagnetic

cutoff (GV/c)

0.4 to 0.5

1.0 to 1.5

1.5 to 2.0

2 to 4

4 to 7

7 to 10

10 to 14

> 14

Geomagnetic cutoff

Preliminary!!

(statistical errors only)

Magnetic poles

( galactic protons)

Secondary reentrant-albedo protons

Magnetic equator

  • Up-ward going albedo excluded
  • SAA excluded
slide24

Preliminary Results B/C

Preliminary

Calorimeter based charge identification!

slide25

Solar modulation

Interstellar spectrum

PAMELA

Ground neutron monitor

sun-spot number

Preliminary!!

(statistical errors only)

Increasing

GCR flux

July 2006

August 2007

February 2008

Decreasing

solar activity

slide27

S1

CARD

CAT

S2

.

TOF

TRK

CAS

S3

CAL

S4

ND

High-energy antiproton analysis

Basic requirements:

  • Clean pattern inside the apparatus
    • single track inside TRK
    • no multiple hits in S1+S2
    • no activity in CARD+CAT
  • Minimal track requirements
    • energy-dependent cut on track c2 (~95% efficiency)
    • consistency among TRK, TOF and CAL spatial information
  • Galactic particle
    • measured rigidity above geomagnetic cutoff
    • down-ward going particle (no albedo)
slide28

electron (17GV)

Antiproton (19GV)

1 GV

5 GV

Antiproton identification

  • dE/dx vs R (S1,S2,TRK) and b vs R proton-concistency cuts
  • electron-rejection cuts based on calorimeter-pattern topology

-1  Z  +1

p (+ e+)

p

e-(+ p-bar)

“spillover” p

p-bar

slide29

Proton spillover background

Minimal track requirements

MDR > 850 GV

  • Strong track requirements:
  • strict constraints on c2 (~75% efficiency)
  • rejected tracks with low-resolution clusters along the trajectory
    • - faulty strips (high noise)
    • - d-rays (high signal and multiplicity)
slide30

10 GV

50 GV

High-energy antiproton selection

p

p-bar

slide31

10 GV

50 GV

High-energy antiproton selection

p

p-bar

R < MDR/10

slide35

Positron selection with calorimeter

p (non-int)

p (int)

  • The main difficulty for the positron measurement is the interacting-proton background:
  • fluctuations in hadronic shower development p0 ggmight mimic pure e.m. showers
  • proton spectrum harder than positron  p/e+ increase for increasing energy

e-

p (non-int)

e+

p (int)

Fraction of charge released along the calorimeter track (left, hit, right)

Rigidity: 20-30 GV

slide36

Positron identification

Energy-rigidity match

e-

( e+ )

Energy measured in Calo/

Deflection in Tracker (MIP/GV)

 ‘electrons’

 ‘hadrons’

p-bar

p

slide37

Positron selection with calorimeter

Rigidity: 20-30 GV

e-

e+

p

Preliminary

+

Fraction of charge released along the calorimeter track (left, hit, right)

  • Energy-momentum match
  • Starting point of shower
slide38

Positron selection with calorimeter

Fraction of charge released along the calorimeter track (left, hit, right)

Flight data:

rigidity: 20-30 GV

Test beam data

Momentum: 50GeV/c

e-

e-

e-

p

e+

e+

p

  • Energy-momentum match
  • Starting point of shower
positron selection
Positron selection

Rigidity: 20-30 GV

Fraction of charge released along the calorimeter track (left, hit, right)

Neutrons detected by ND

e-

e-

p

e+

e+

p

  • Energy-momentum match
  • Starting point of shower
slide40

Positron selection

Energy loss in silicon tracker detectors:

  • Top: positive (mostly p) and negative events (mostly e-)
  • Bottom: positive events identified as p and e+ by trasversal profile method

p

e-

p

e-

p

e+

p

e+

Rigidity: 10-15 GV

Rigidity: 15-20 GV

slide41

Proton background evaluation

Preliminary!!

Rigidity: 6-8 GV

e-

Fraction of charge released along the calorimeter track (left, hit, right)

+

Constraints on:

e+

Energy-momentum match

p

Shower starting-point

p

slide42

Positron to Electron Fraction

Charge sign dependent solar modulation

End 2007:

~20 000 positrons total

slide43

Electron to positron ratio

Preliminary

e-/e+

Rigidity (GV)

U.W. Langner, M.S. Potgieter, Advances in Space Research 34 (2004)

slide45

Increase of low energy component

December 13th 2006 event

from 2006-12-1 to 2006-12-4

slide46

Increase of low energy component

December 13th 2006 event

from 2006-12-1 to 2006-12-4

from 2006-12-13 00:23:02 to 2006-12-13 02:57:46

slide47

Increase of low energy component

December 13th 2006 event

from 2006-12-1 to 2006-12-4

from 2006-12-13 00:23:02 to 2006-12-13 02:57:46

from 2006-12-13 02:57:46 to 2006-12-13 03:49:09

slide48

Decrease of high energy component

Increase of low energy component

Increase of low energy component

December 13th 2006 event

from 2006-12-1 to 2006-12-4

from 2006-12-13 00:23:02 to 2006-12-13 02:57:46

from 2006-12-13 02:57:46 to 2006-12-13 03:49:09

from 2006-12-13 03:49:09 to 2006-12-13 04:32:56

slide49

Increase of low energy component

December 13th 2006 event

from 2006-12-1 to 2006-12-4

from 2006-12-13 00:23:02 to 2006-12-13 02:57:46

from 2006-12-13 02:57:46 to 2006-12-13 03:49:09

from 2006-12-13 03:49:09 to 2006-12-13 04:32:56

from 2006-12-13 04:32:56 to 2006-12-13 04:59:16

slide50

Increase of low energy component

December 13th 2006 event

from 2006-12-1 to 2006-12-4

from 2006-12-13 00:23:02 to 2006-12-13 02:57:46

from 2006-12-13 02:57:46 to 2006-12-13 03:49:09

from 2006-12-13 03:49:09 to 2006-12-13 04:32:56

from 2006-12-13 04:32:56 to 2006-12-13 04:59:16

from 2006-12-13 08:17:54 to 2006-12-13 09:17:34

slide51

Modulation of galactic cosmic ray intensity

~5% Decrease at mid-latitude

GLE

Jungfraujoch Neutron Monitor (Rc~4.5 GV)‏

The 14th December 2006 Forbush Decrease

Erwin O. Flückiger

slide52

The 14th December 2006 Forbush Decrease

from 2006-12-1 to 2006-12-4

Preliminary

slide53

The 14th December 2006 Forbush Decrease

from 2006-12-1 to 2006-12-4

from 2006-12-14 08:58:42 to 2006-12-14 11:59:57

Preliminary

(red - black) / black

slide54

The 14th December 2006 Forbush Decrease

from 2006-12-1 to 2006-12-4

from 2006-12-14 12:00:01 to 2006-12-14 23:59:59

(red - black) / black

slide55

The 14th December 2006 Forbush Decrease

from 2006-12-1 to 2006-12-4

from 2006-12-15 00:00:01 a 2006-12-15 23:59:54

Preliminary

(red - black) / black

slide56

The 14th December 2006 Forbush Decrease

from 2006-12-1 to 2006-12-4

from 2006-12-16 00:00:04 a 2006-12-16 23:59:59

Preliminary

(red - black) / black

slide57

The 14th December 2006 Forbush Decrease

from 2006-12-1 to 2006-12-4

from 2006-12-17 00:00:04 a 2006-12-17 23:59:59

Preliminary

(red - black) / black

slide58

The 14th December 2006 Forbush Decrease

from 2006-12-1 to 2006-12-4

from 2006-12-17 00:00:04 a 2006-12-17 23:59:59

Preliminary

(red - black) / black

slide60

SAA morphology

Latitude

Altitude

Altitude

Neutron rate

(background)

Longitude

South-Atlantic Anomaly (SAA)

SAA

slide61

Fluxes in SAA

B > 0.30 G

0.22 G ≤ B < 0.23 G

0.21 G ≤ B < 0.22 G

0.20 G ≤ B < 0.21 G

0.19 G ≤ B < 0.20 G

B < 0.19 G

Always: 10 GV < cutoff < 11

Preliminary

slide62

Conclusions

  • PAMELA is continously taking data since July 2006
  • Presented preliminary results from ~600 days of data:
    • Antiproton charge ratio (~1 GeV ÷100 GeV)
      • no evident deviations from secondary expectations
      • more data to come at lower and higher energies (up to ~150 GeV)
    • Positron charge ratio (~400 MeV ÷10 GeV)
      • indicates charge dependent modulation effects
      • more data to come at lower and higher energies (up to ~200 GeV)
    • Galactic primary proton spectra
      • primary spectra up to Z=8 to come
    • Galactic secondary-to-primary ratio (B/C)
      • abundance of other secondary elements (Li,Be) and isotopes (d,3He) to come
    • High energy tail of proton SEP events
      • spectra of other components (electrons, isotopes,…) to come
    • Radiation belts
      • morphology
      • spectrum
  • PAMELA is already providing significant experimental results, which will help in understanding CR origin and propagation
  • More exciting results will come in the next future!
slide63

A calorimeter self-triggering showering event. Note the high energy release in the core of the shower and the high number (26) neutrons detected.

CALO SELF TRIGGER EVENT: 167*103 MIP RELEASED

279 MIP in S4

26 Neutrons in ND

ad