High-energy Performance of X-ray Imaging Spectrometers

on board Astro-E

Kensuke ImanishiH. Awaki, T. G. Tsuru, K. Hamaguchi,

H. Murakami, M. Nishiuchi, and K. KoyamaKyoto University, Japan

XIS (X-ray Imaging Spectrometer)

•X-ray CCD camera on board Astro-E•Front illuminated, Frame transfer

Number of pixels 1024x1024 Energy band 0.2-12keV

Pixel size 24x24μm Temperature -90Åé

Energy resolution 130eV@6keV

Depletion Layer ~70μm

Main properties of XIS

Pulse Height distribution of XIS (55Fe)

Mn K(5.89keV)

Mn K(6.49keV)Low energy tail

Peak structure

0 20001000Channel

104

10 -1

100

101

102

103

Cou

nts

Divide the response function into 6 components

Main peak

Sub peak

Trianglecomponent

Constantcomponent

Si escapeSi line

Channel

Cou

nts

X-rayEnergy[ keV ]

0 5 10

Al Cl Ti55Fe

Ni ZnFe Se

Kyoto UniversityOsakaUniversity

Obtained data pointsFluorescent X-rayRadio isotope

Si K edge

Gat

e

Insu

lato

r

Dep

letio

n

Mai

n pe

ak,

Sub

pea

k, T

riang

le c

ompo

nent

Mai

n

peak

Tria

ngle

com

pone

ntSub

pea

k

X-r

ay

elec

tron

clou

d

Ch

ann

el

Sto

p

Channel vs X-ray energy

Ene

rgy

reso

lutio

n [e

V]

Energy resolution (= Main peak width)

200

100 FWHM =2.35Wsi N2 +F

WsiE

FWHM =2.35Wsi N2 +F

WsiE + N'E2

Readout noisePoisson statistics

Wsi : mean ionization energyF : Fano factor

eV

Con

stan

t com

pone

nt

Ass

um

pti

on

1.

Ele

ctro

n d

istr

ibuti

on is

sphere

wit

h u

nif

orm

den

sity

.2.

Ele

ctro

n c

loud r

adiu

s =

1.7

1X

10

-6E

1.7

5 [c

m]

(Janesi

ck e

t al. 1

986

)3.

Ele

ctro

ns

genera

ted in t

he insu

lato

r are

not

coun

ted.

data

calc

ula

tion

100

101

102

103

Counts

104

10 -1

050

010

0015

00C

hann

el

Gat

e

Insu

lato

r

Dep

letio

n

Relative Intensity of constant component

Blue : dataGreen : calculation resultRed : multiplied the calculation result by 1.59

Energy [keV]1 10

Co

nst

ant

inte

nsity

/ M

ain

pe

ak in

ten

sity10 -1

10 -2

Si e

scap

e an

d S

i lin

eS

i flu

ores

cent

X-r

ay (

1.74

keV

)

12

En

erg

y [k

eV]

10

2

Escape intensity/Main peak intensity 10

-3

10

-2

data

sim

ulat

ion

mod

el1

3

Tot

al

3

Si e

scap

eS

i lin

eS

i esc

ape

Si l

ine

Si f

luor

esce

nt X

-ray

(1.

74ke

V)

12

En

erg

y [k

eV]

10

2

Si line intensity/Main peak intensity 10 -3

10

-2

data

sim

ulat

ion

mod

el2 3

Tot

al

3

Si e

scap

eS

i lin

eS

i esc

ape

Si l

ine

10 -4

Reproducibility of the response function

55Fe (Mn)

K:6.489keV

K:5.894keV

Mn L

response function

Summary

• The response function of XIS CCD camera was constructed.– We considered the physical process inside the

CCD, and divided the response into 6 components.

– Shape and Intensity of these components were determined as a function of X-ray energy.