G. LAMANNA Journée Spatiale IN2P319/2/2009 G. LAMANNA Journée Spatiale IN2P3 19/2/2009 POLAR un Polarimètre spatial à grande ouverture pour la mesure des

G. LAMANNA G. LAMANNA Journée SpatialeJournée Spatiale IN2P3 IN2P3 19/2/2009 19/2/2009

POL A

R

POLARPOLARun Polarimètre spatial à grande ouverture pour la

mesure des rayons X émis par des Sursauts Gamma (GRB)

(http://lappwiki01.in2p3.fr/POLAR-FR)(http://lappwiki01.in2p3.fr/POLAR-FR)

Giovanni Lamanna

LAPP (IN2P3/CNRS) Laboratoire d’Annecy-le-vieux de Physique des Particules


• Electromagnetic radiation (EM) has 4 measurable quantities:– Direction– Intensity– Energy– Polarization

• Measurements of polarization provide information about the radiation mechanism but they have not been enough explored• Difficult to do with actual detectors

• Wrong measurements published (claim 80%+- 20%) (GRB 021206 accidental coincidences)

• A lot of theoretical interests ( 122 citations)

Polarimetry

POLARPOLAR

• POLAR is a Compton hard X-ray GRB polarimeter using proven technologies:

40x40 homogeneous array of 6x6x200 mm3 low Z scintillator plastic bars and PM detectors

• Measuring the PROMPT signal of the GRBs within a wide FoV (≈ ⅓ of the sky)

• Perform first ever successful polarization measurement of hard X photons in space with

high statistical significance and controlled systematic effects.


• Transient events ranging in duration from a fraction of a second up to a few hundred seconds.

Gamma Ray Burst (GRB)

• Energetic bursts that mark the most violent, cataclysmic explosions in the universe. Currently about 2 to 3 GRBs detected per week. They are flashes of gamma rays, at random places in the sky and at random times.

GRB 910412, 12 April 1991

Two types of GRBs: 1) Soft-spectrum Long burst (death of massive stars);

2) Hard spectrum Short burst (merger of compact star binaries: ns-ns; ns-bh..)

Both result in a Black Hole formation and regardless of the progenitor a “fireball” central engine would be responsible of a relativistic jet from the center of the explosion (bulk

Lorentz factor > 100.)


• Fireball Modelhigh values excluded

Plin ~ 10-20 %

• Cannonball Modelfull range possible

Plin = 0 - 100%(depends only on .)

• Electromagnetic Modelwell defined, moderatePlin ~ 50 %

See papers discussing various models:T.Piran, A.Dar & A. De Rujula, M.Lyutikov, D.Eichler, G.Ghisellini, D.Lazzatti, M.Medvedev, E.Rossi etc.

From M.Lyutikov, 2003

GRB Polarization

Theories on the GRB production mechanism can be constrained bydifferent degrees of linear polarization:


PS Bars

PMT(mm)

Weight (kg)

Dimension (cm)

40*40 5*5 20 30*30

1600 PS bars: 25 x 8x8*6mm*6mm*20cm

Light, fast and low Z plastic (in favor of Compton effect)

BC400: rad-hard and chemically stable

Wavelength (Peak)

420 nm

Uniformity 2-3

MAPM H8500 (8*8 anode pixel)

The POLAR detector


COMPTON POLARIMETRY: Basic Principles

Geometry of the large angle Compton scattering. The strategy is to look for the two bars where interactions occur: first Compton and second Compton or Photoelectric.


The POLAR detector

The scientific objectives lead to the following instrument specifications: Effective detection area 400 cm2 (at 200 keV) Incoming photon energy 50 keV to 500 keV A large modulation factor ~40% (at 200 keV) A large FOV (deep space view) 1/3 of the skyTotal Mass < 30 kgMean power Consumption < 30 WTelemetry (continuous readout) < 100 kBit/s

The POLAR project is in the middle of an hybrid “Phase A/B”: - Demonstrator is under test on polarized beam, meanwhile an Engineer Model (EM) is under development

- The EM project (e.g. Phase B) has recently produced a Preliminary Technical Design Report for all sub-projects: Mec, Ele.etc..


• Analysis uses two largest energy deposits with E thr= 5 keV (corresponding to electron recoil energy from 50 keV photon scattered at 90o) (trigger activation: at least 2 channels)

• Optical insulation and thin (≈ 1 mm) carbon fiber outside shielding (stopping electrons with E< 500 keV or protons E< 13 MeV)

• No active shielding; but outer layers can be used if needed for a (“topological”) trigger

• Upper threshold Esum< 300+ keV (total sum) (TBC)

Monte Carlo Results

• Maximum effective area for monochromatic photons ·A = Aeff ≈ 350 cm2

• Polar angular dependence varies within 15% only• Maximum Modulation Factor is 30% - 40%

• Constant values kept up to more then = 30 for off-

axis GRB

0 30 60 90 120 150 180100

150

200

250

300

350

400

Cou

nts

(a.u

.)

Azimuth Angle

Modulation Curve

Fit function: N=A·cos(2)+½)+B


Background:

• Cosmic rays removed by upper energy threshold

• Diffuse background E,bg>10 keV Fdif=2.46 /cm2/sr/s – 430 coinc./s

• Non-GRB sources – e.g. Crab FCrab=0.7 /cm2/sr/s

• S/C induced ’s – ISGRI estimated Find=0.02 /cm2/sr/s

GRB signals:

Monte Carlo Results

• MDP = E=10-5 erg/cm2 → MDP3 ≈ 10% (example LTC GRB060418 by RHESSI)

• Statistics based on BATSE catalogue

TBSSn /)(/ 100

0 10 20 30 40 50 60 70 80 90 1000

20

40

60

80

100

120

140

160

180

Minimum Detectable Polarization with 3σ (%)

Num

ber o

f GR

Bs

(N <

MD

P)

One year observation of POLAR

TS2/DM2 FOV = 2π

59.448.636.824.412.72.9Number of GRB in 1 year

30%25%20%15%10%5%MDP


Laboratory Tests


The POLAR detector: Space know-how

AMS-ECAL @ LAPP:Optical coupling


Mechanics


Laboratory tests with pulses from LEDs and with several radioactive sources to calibrate the energy response.

A modulation curve obtained where the reconstructed modulation factor is 17% ± 3%. The polarization angle is reconstructed with good accuracy (input photons: 90°, reconstructed angle: 91.7° ± 4.4°).

Laboratory Tests


POLAR International Collaboration

SWITZERLANDISDC - Geneva Observatory:Nicolas Produit Daniel Haas (POLAR PostDoc.)

PSI-Villigen:Wojtek HajdasAliko Mchedlishvili

University of Geneva:Martin Pohl Catherine LelucDivic RapinSilvio Orsi (POLAR PostDoc.)Estela Suarez (POLAR PhD student)

POLANDIPJ:Michal Gierlik Radoslaw Marcinkowski

CHINAIHEPShuang-Nan Zhang Bobin WuXiong Shaolin (POLAR PhD student)

FRANCELAPP – IN2P3-Annecy:Giovanni LamannaJean-Pierre VialleRichard Hermel Nadia Fouque

LAM-INSU-Marseille:Stephane BasaAlain Mazure

LAPTH – CNRS -Annecy:Pascal Chardonnet

Scheduled POLAR flight onboard the Chinese

SpaceLab in 2013.


Presented by Shuang-Nan Zhang (HXMT-CoPI) at GRB2008 ConferencePresented by Hesheng Chen (IHEP Director) at ASPERA-Roadmap Workshop Brussels:

POLAR is a Chinese Astroparticle priority.


POLAR – IN2P3 know-how

Members of the POLAR collaboration have a broad experience in designing building and operatinginstruments for high energy physics and space research.

The FRENCH Team have already worked on the design, construction and operation of the several instruments and have large experience in on-line, off-line and scientific analysis software. Know-how IN2P3 (LAPP in particular): - Micro-electronics (analogical and digital) (ASIC conception); - Space radiation detectors R&D, qualification, calibration, commissioning and operation; - Space radiation environment - On-line (monitoring, data reduction, trigger,…) software - Off-line (reconstruction, calibration, analysis, … ) software

- Computing for off-line data analysis (from low size to GRID-size)


MAPRA: Multi Anode Polar Readout Asic,

• Characteristics

– 64 PMT channels input

– Variable gain

– 64 GTL outputs

– Multiplexed direct signal output

– 3 thresholds loaded

• Technology : AMS SiGe 0.35µm

– Area 12 mm2

– Dissipation O(100 mW)

LAPP - MAPRA ASIC PROJECT

100% Modulation factor vs. Uniformity

0

10

20

30

40

50

0 100 200 300

Energy (keV)

Mod

ulat

ion

fact

or (%

))

Non-UniformIdealEnergy Smearing

• Lack of uniformity affects the modulation factor: Non-Uniformity of PM has a strong influence

- Design finalisé en 2008.

- Première prototype le mois prochain

- Tests courant 2009

- Production finale en 2010

French funding (Universite de Savoie & LAPP) for the MAPRA ASIC (2008-2010) and cooperating with Omega-LAL-IN2P3.


According to 2008 (CNES & ANR) proposals the French POLAR teams (LAPP+LAM+LAPTH) would be applied, and in certain cases would lead: 1) Detector front-end electronic development (LAPP); 2) Physics, data management and software development (LAPP, LAPTH and LAM); 3) Space Qualification (LAM);

Sub-project n.1: “Detector front-end electronic development” MAPRA ASIC design; DAQ and trigger implementation;

Electronic test bench with the EM sector;

Sub-project n.2: “Physics, data management and software development” Monte Carlo simulation and data analysis

Simulation of trigger acquisition and data flow; Case study of source of systematic affecting modulations curves.

Data management Data-challenge production and Data-Archive development Tests on data exchange and coordinated analysis with SVOM and integration with other data (SVOM, GLAST, IPN,…) Physics Phenomenological studies of GRBs polarization Simulation according to models and physical constraints (Data Challenge)

Sub-project n.3: “Space Qualification”List of main aims: Work-plan and deliverables: EM Qualification campaign

French participations

Presently only the MAPRA-prototypeis funded (BQR- UNI. SAVOIE )


Conclusions

• POLAR is a Compton hard X-ray GRB polarimetry based on particle physics technology to perform polarization measurement of hard X photons in space with high statistical significance and controlled systematic effects.

• POLAR-France is a collaboration among Particle Physicists (IN2P3), Astrophysicists (INSU) and Theoreticians (LAPTH-CNRS).

• POLAR and polarimetry have met the interest of the GRB-French community. Following the participation at the 2008 French GRB-POLAR workshop (http://lappweb.in2p3.fr/GRB2008/fr/index.html):

• POLAR is scheduled to fly on Chinese SpaceLab in 2013 :

First international scientific collaboration in the Chinese space manned program.

• POLAR-French participation depends on the future funding (CNES, ANR, IN2P3,….)

- A scientific collaboration between POLAR and SVOM, is taking place. The SVOM community strongly support POLAR as a low cost “natural” complementary device for an extremely important complementary scientific measurement. -The French scientific community will benefit having privileged access to a set of unprecedented, precise and important scientific data.

Documents

G. LAMANNA Journée Spatiale IN2P319/2/2009 G. LAMANNA Journée Spatiale IN2P3 19/2/2009 POLAR un Polarimètre spatial à grande ouverture pour la mesure des