x-ray polarimetry with gas proportional counters through rise-time k. hayashida, t. horikawa, y....

X-ray Polarimetry with gas proX-ray Polarimetry with gas proportional counters through riseportional counters through rise

-time-time

K. Hayashida, T. Horikawa, K. Hayashida, T. Horikawa, 　　　　　　　　 Y. Nakashima, H. Tsunemi Y. Nakashima, H. Tsunemi

(Osaka University, Japan)(Osaka University, Japan)

X-ray Polarimeters in AstronomX-ray Polarimeters in Astronomyy Bragg Crystal ReflectionBragg Crystal Reflection

OSO8,ArielV satellites (1970’s) OSO8,ArielV satellites (1970’s) Compton ScatteringCompton Scattering

Planned for Spectrum X-GammPlanned for Spectrum X-Gamma mission (1990’s)a mission (1990’s)

Tracking Photo-electron EmisTracking Photo-electron Emission Directionsion Direction X-ray CCD (Tsunemi et al., 199X-ray CCD (Tsunemi et al., 199

2)2) Micro electrodes Gas Chamber Micro electrodes Gas Chamber

(Costa et al., 2001; Tanimori et (Costa et al., 2001; Tanimori et al., 1999; Sakurai et al., 1996)al., 1999; Sakurai et al., 1996)

Observations have been stagnant since 1970’s for more than 20 years.

Rise Time PolarimeterRise Time Polarimeterusing Gas Proportional Counter using Gas Proportional Counter

Proposed by Riegler et al., Sanford et al., in 1970.Proposed by Riegler et al., Sanford et al., in 1970. We re-examined the method. (Hayashida et al., 1999, NIWe re-examined the method. (Hayashida et al., 1999, NI

MA, 421,p.241) MA, 421,p.241)

Anode

Electron Cloud

E��

Rise Time = Short Rise Time = Long

// E��

Anode Anode E��

X-ray Photon

Working principle

Experiment at Synchrotron Experiment at Synchrotron Facility (1992-1993)Facility (1992-1993)

Anode Direction

Electric Vector // Vertical Direction

Double Crystal Spectrometer

BL14CVacuum Air

Pb Shield

2mmHole

Vertical Wiggler

SOR

Xe Gas Proportional Counter

Ex=10-40keV (PEx=10-40keV (Pbeambeam~0.8; measured)~0.8; measured) Xe proportional counter Xe proportional counter

Xe:736mmHg + COXe:736mmHg + CO22:25mmHg:25mmHg Multi cell type; 5cm depth, 5cmx30cm for each cellMulti cell type; 5cm depth, 5cmx30cm for each cell Anode 50Anode 50m Be; HV=1950Vm Be; HV=1950V

Irradiate position =1.2cm from anode

(Hayashida et al., 1999, NIMA, 421,p.241)(Hayashida et al., 1999, NIMA, 421,p.241)

Rise Time MeasurementRise Time Measurement

0

20

40

60

80

100

-2.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0

Dig

itize

d V

olta

ge

(m

V)

Time(microsec)

E=40keV

PH

80% of PH

20% of PH

RT

Xe Gas Proportional Counter

Pre-AmplifierDigital Storage Oscilloscope

Shaping Amp Scaler

GPIB

Personal Computer

Sampling the output pulse from CSPA with Sampling the output pulse from CSPA with Digitized Oscilloscope.Digitized Oscilloscope.

RT and PH are determined from the waveform RT and PH are determined from the waveform data transferred to the computerdata transferred to the computer

Results (Ex=34keV)Results (Ex=34keV)

0

20

40

60

80

100

120

140

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

34 keV =0deg.

Num

ber

of

events

risetime(microsec)

0

20

40

60

80

100

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

34keV Q=90deg.

Num

ber

of

events

risetime(microsec)

0

20

40

60

80

100

120

140

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

34keV Q=180deg.

Num

ber

of

events

risetime(microsec)

0

20

40

60

80

100

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

34keV Q=270deg

Num

ber

of

events

risetime(microsec)

0.40

0.45

0.50

0.55

0.60

0 90 180 270(deg)

34 keV

rise

tim

e (

mic

rose

c)

RT distribution RT vs


X-ray Energy X-ray Energy dependencedependence

0.40

0.45

0.50

0.55

0.60

0 30 60 90

rise

time

(mic

rose

c)

(deg)

10keV

0.40

0.45

0.50

0.55

0.60

0 30 60 90

rise

tim

e(m

icro

sec)

Q (deg)

20keV

0.40

0.45

0.50

0.55

0.60

0 30 60 90

rise

tim

e(m

icro

sec)

Q (deg)

30keV

0.40

0.45

0.50

0.55

0.60

0 30 60 90

rise

time

(mic

rose

c)

(deg)

34keV

0.40

0.45

0.50

0.55

0.60

0 30 60 90

rise

tim

e(m

icro

sec)

Q (deg)

36keV

0.40

0.45

0.50

0.55

0.60

0 30 60 90

rise

tim

e(m

icro

sec)

Q (deg)

40keV

Note: XeNote: Xe-K edge =34.6ke-K edge =34.6keV V

Events were seleEvents were selected using PH.cted using PH.


Modulation Factor MModulation Factor M

0.0

0.1

0.2

0.3

0.4

0.5

0 10 20 30 40 50

Mo

du

lati

on

Co

ntr

ast

Inciden X-ray Energy (keV)

2 2

90 0

2

90 0 / 2

: STD of RT distribution

RT beam

RT RTRT

RT

RT RTM

P

min

Minimum Detectable Polariza

c

ti

f

on (MDP)

event

aP

M N

M


Figure of merit for polarimter, larger the better.

Extra Experiment for VerificationExtra Experiment for Verification

0.40

0.45

0.50

0.55

0.60

0 30 60 90

(deg)

36keV Polarized

rise

tim

e(m

icro

sec)

0.40

0.45

0.50

0.55

0.60

0 30 60 90Q (deg)

Sn K a (25.2 keV)ri

seti

me(m

icro

sec)

0.40

0.45

0.50

0.55

0.60

0 30 60 90Q (deg)

Sn K b (28.5 keV)

rise

tim

e(m

icro

sec)

Thin Sn filter was placed at the beam exit, whicThin Sn filter was placed at the beam exit, which produced Sn Kh produced Sn K,K,K fluorescent X-rays in additi fluorescent X-rays in addition to polarized 36 keV X-rays. on to polarized 36 keV X-rays.


Polarized X-ray Beam Line at OsakaPolarized X-ray Beam Line at Osaka

Measurement Chamber

Double Crystal Spectrometer

X-ray Generator

Monochromatic beam with linear polarization degree of 40-50% is obtained. (Koike et al., 2000, SPIE4012, p.414)

Experiment at Osaka Beam Line Experiment at Osaka Beam Line (2001-2002)(2001-2002)

Gas PCsGas PCs Ar gas flow type PCAr gas flow type PC

Wire 50Wire 50mm Quenching gas (CH4) of Quenching gas (CH4) of

various contents were exvarious contents were examined.amined.

Xe gas shield type PC (tXe gas shield type PC (the same one used in Syhe same one used in Synchrotron Facility)nchrotron Facility)

Data taking system waData taking system was upgraded. s upgraded.

X-ray

X-ray

E90,270

0,180

angle

RT vs angle

2.45

2.5

2.55

2.6

2.65

2.7

- 90 0 90 180 270 360 450[degree]

RT[

usec

]

0.2700.2650.260

0.2500.255

0.245

However, Results are …However, Results are …M vs E

-0.05

0

0.05

0.1

0.15

25 30 35 40 45 50E[keV]

M

Gas Content　　 Xe96.7%+CO23.3%　　 Ar 90% +CH410%　　 Ar99.3%+CH40.7%

Contents of Quenching Gas is very sensitive to RT. Contents of Quenching Gas is very sensitive to RT. Ar 99.3% +CHAr 99.3% +CH44 0.7% provided M of 0.05-0.1. 0.7% provided M of 0.05-0.1. Small!Small! More seriously, the same Xe counter used in 1992-1993 yielMore seriously, the same Xe counter used in 1992-1993 yiel

ded M of less than 0.05. ded M of less than 0.05. CONTRADICTION!CONTRADICTION!

Incident position

12mm from anode for Xe PC

10mm from anode for Ar PC

Preliminary Simulation using Preliminary Simulation using EGS4EGS4

Ar-Gas P=1atm Ex=20keV Ar-Gas P=1atm Ex=50keV

EGS4 (Electron Gamma Shower Simulator ver4) + KEK low EGS4 (Electron Gamma Shower Simulator ver4) + KEK low energy extensionsenergy extensions

Energy deposit and path of photoelectrons are simulated.Energy deposit and path of photoelectrons are simulated. Large effect of multiple scattering is observed. Large effect of multiple scattering is observed.

10mm1mm

E

M expected from EGS4 SimulationM expected from EGS4 Simulation

0

0.1

0.2

20 30 40 50

M (Ne) M (Ar) M (Xe)

Ex(keV)

0.01

0.1

1

20 30 40 50

Ne _|_(cm)

Ne //(cm)

Ar _|_(cm)

Ar //(cm)

Xe _|_ (cm)

Xe // (cm)

Ex(keV)

Dispersion of the distance to anode () cm M

2

for each photo-absorption event

/

( ) /

i i i

i i i

d E d E

E d d E

•Small energy dependence

•M=0.03-0.06 for Ar, <0.03 for Xe

•NOTE: gas processes (diffusion, avalanche etc) is not considered.

*) If multiple scattering does not exist, M would be 0.78.

M

Siz

e

(cm

)

Solution of the Contradiction ?Solution of the Contradiction ? Strong dependence of X-ray Strong dependence of X-ray

incident position on RT was incident position on RT was observed.observed.

Misalignment of rotation axis Misalignment of rotation axis could have made an artifact could have made an artifact modulation.modulation.

But,But, the modulation should h the modulation should have 1 peak / 360deg, not likave 1 peak / 360deg, not like observed 2 peaks / 360dee observed 2 peaks / 360deg.g.

Sn-filter result was not explaSn-filter result was not explained with the misalignment, ined with the misalignment, either.either.

0.40

0.45

0.50

0.55

0.60

0 90 180 270(deg)

34 keV

rise

tim

e (m

icro

sec)

Anode

12mmExperiment at Synchrotron Facility is planed in this Autumn.

Feasibility Study PC polarimeter Feasibility Study PC polarimeter

Merit of PC polarimeterMerit of PC polarimeter Large effective area is easily realized without mirrors.Large effective area is easily realized without mirrors. Suitable for balloon experiment.Suitable for balloon experiment.

T=100ks

0.1

1

10

100

10-3 10-2 10-1 100 101

XePC(4000cm2,20-40keV)ArPC(4000cm2,20-40keV)

flux(Crab)

Pm

in %

(99

% c

onfid

ence

)

Crab Nebula

P=19% @2.6keV,5.2keV

SummarySummary

Gas proportional counter polarimeter with rise tiGas proportional counter polarimeter with rise time measurement is introduced. me measurement is introduced.

Previous experiment at Synchrotron facility proviPrevious experiment at Synchrotron facility provided M of 0.1-0.3 with Xe PC, while recent experided M of 0.1-0.3 with Xe PC, while recent experiment (Xe PC, Ar PC) provides much smaller M.ment (Xe PC, Ar PC) provides much smaller M.

Preliminary simulation also suggests M <0.1. Preliminary simulation also suggests M <0.1. No firm solution has not yet been obtained for thNo firm solution has not yet been obtained for th

e contradiction. e contradiction. Sorry for inconclusive, confusinSorry for inconclusive, confusing results.g results.

Feasibility Study PC polarimter Feasibility Study PC polarimter

0.01

0.1

1

10

100

10-3 10-2 10-1 100 101

CCD(6micron/50micron/100cm2)

CCD(12micron/50micron/100cm2)

XePC(4000cm2,20-40keV)

ArPC(4000cm2,20-40keV)

SXRP(Li)

Thomson(Li,628cm2,M=0.5,10-20keV)

MPGC+SODART(present,2-10keV)

flux(Crab)

Merit of PC polarimterMerit of PC polarimter Large effective area is easily realized without mirrors.Large effective area is easily realized without mirrors. Suitable for balloon experimentSuitable for balloon experiment

T=100ks

Pm

in %

(99

% c

onfid

ence

)

x-ray polarimetry with gas proportional counters through rise-time k. hayashida, t. horikawa, y....

Documents

anode hayashida

principle slide

mmhg xe

xe gas shield type pc

kev xrays

gas proportional counters

kev p beam

polarized xray beam