Performance of a Si PIN photodiode at low temperatures and in high magnetic fields · 2007. 4. 16. · High field measurements The behaviour of the detector in magnetic fields up

Performance of a Si PIN photodiode

at low temperatures and in high magnetic

fields

Frederik Wauters*, Ilya Kraev*, Nathal Severijns*,

Sam Coeck*, Michael Tandecki*, Valentin Kozlov*,

Dalibor Zákoucký**

*Katholieke Universiteit Leuven (Belgium)

**Nuclear Physics Institute, Rez (Czech Republic)

Overview

• The detector and it’s usage• General properties

• Tests towards the use in a LTNO setup

• High field measurements• Round up

• Future plans

The detector and it`s usage

Si PIN photodiode:

A p-i-n junction working as a 500 µm think window-less Si detector.

Type: S3590-6

from H

AM

AM

ATSU

Si PIN photodiode:


• Light detection


• Read out of scintillators

• ! Light level has to be

high enough

* Datasheet Hamamatsu

*

Type: S3590-6

from H

AMAM

ATSU

Si PIN photodiode:


• Light detection


• X-ray detection

*

*Datasheet Hamamatsu** Y. Inoue et al NIMA 368 (1996) 556-558

**

• High efficiency for low

energy`s (< 10 keV)

• ! Noise threshold

Type: S3590-6

from H

AMAM

ATSU

Si PIN photodiode:


• Light detection


• X-ray detection

*


** • α-ray detection

• Thin front dead

layer

• ! Radiation damageType: S3590-6

from H

AMAM

ATSU

Si PIN photodiode:


• Light detection


• X-ray detection

*



• electron detection

• Fully stop

energy`s

< 350 keV

• Low

background

from high

energy γ`s

60Co

Type: S3590-6

from H

AMAM

ATSU

Si PIN photodiode:


• Light detection


• X-ray detection

*



• electron detection

• Fully stop

energy`s

< 350 keV

• Low

background

from high

energy γ`s

60Co

Type: S3590-6

from H

AMAM

ATSU

General properties

• 9 x 9 mm active area

• 500 µm depletion layer thinkness• Maximum reverse bias : 150 V• Low capacitance and leakage current(relative to other photodiodes)

• Spectral response max. at 980 nm

General properties




Dark current drops fast with decreasing temperature

Even a little bit of cooling can decrease the detector noise

General properties




The insensitive surface layer (SiO2)

was measured with α-particles:

0,35 µm ± 0,02 µm *

* Y. Atimoto et al., NIMA 557 (2006) 684-687

*

Important for measurements with

α-particles and low energy X-rays

General properties




The surface of a simular PIN diode was scanned with a 2 MeV He microbeam:Good charge collection efficiency at the center of the detector but satellite peaks and other unwanted effect`s at the edges.**

** A. Simon et al., NIMB 231 (2005) 507-512

**

Collimator

Tests towards the use in a LTNO setup

Requirements: • Sensitive for α- and β-radiation but not to sensitive for γ`s.High energy γ`s generate an unwanted comptonbackground.

• Be able to work close to 4K.• Be able to work in magnetic fields up to 0,5 T

Standard setup:

Vacuum chamber/

cryostat

Pre-amplifier

(Canberra 2003)

Shaping

amplifierADC

DAQ

PC

On the scope

1 or 2 µsshaping time




αααα`s and ββββ`s at room temperature:207Bi source

482 keV(K line)

554 keV & 566 keV

(L & M line)

976 keV

(K line)

PulserX-rays

Resolution: 6,5 keV 7,1 keV

Noise threshold at 23 keV

Typical resolution at 6 MeV is 20 keV,

best is 14 keV.




αααα`s and ββββ`s at room temperature:

482 keV

(K line)207Bi measurendwith different bias

voltages

From 30 V on, no big changes in the

peakshape.Standard bias: 140 V



• Be able to work close to 4K.• Be able to work in magnetic fields up to 0,5 T.

From room temperature to 77 K to close to liquid helium temperature :

Liquid nitrogen

Room

temperature

Liquid helium

& 0,5 T


Our conclusions until now:

• The detector showed good behaviour close to 4 K and in a field up to 0.5 T

β-asymmetry measurements

with 60Co

Half-life measurements of

α-emittors at low temperatures in

metals



• The detector showed good behaviour close to 4 K and in a field up to 0,5 T• We can reproduce spectra with Monte-Carlo simulations (GEANT4)




• Resolution between two detectors can differ by ± 1keV• Peformance can go down in time

Radiation damage

Temperature cycles




• Resolution between two detectors can differ by ± 1keV• Peformance can go down in time

• The detector is quite sensitive to vibrations (LN2 filling)• Bringing the unamplified signal outside the setup is not optimal

→ noise

High field measurements

The behaviour of the detector in magnetic fields up to 11 T

was tested to investigate the possibility to use this detector in an ion-trap.

What is already know? • An Avalanche PhotoDiode (APD) is not affected by fields up to 7,9 T*.

• Silicon drift detectors work well in fields up to 4,7 T**. The position

resolution can be retained by tuning the angle between the detector and

the incident particles***.

* J. Marler et al., NIMA 449 (2000) 311-313** S.U. Pandey et al., NIMA 383 (1996) 537-546*** A. Castoldi et al., NIMA 399 (1997) 227-243


The behaviour of the detector in magnetic fields up to 11 T

was tested to investigate the possibility to use this detector in an ion-trap.

B

• Field ⊥ PIN diode• In high fields e± with energy`s that can be fully stopped by the detector

follow the field lines• More particles at grazing incidence

• The performance of the PIN diode was measured in different magnetic

fields:0 T, 0,5 T, 2 T, 5 T, 7 T, 9 T, 11 Tthis over a period of two weeks.


Experimental setup

77 K

4 K

Room temperature

shield

Superconduction

magnet up to 17 T

Source (207Bi/57Co)

PIN diode

Usual position of

the detector

Charge sensitive

pre-amplifier

Amplifier

ADC

DAQ


Experimental setup


General conclusion:

• The detector still works even in a magnetic field up to 11 T.

• The performance of the detector after the field measurent did not go down.


General conclusion:

• The detector still works even in a magnetic field up to 11 T.

• The performance of the detector after the field measurent did not go down.

! BUT !

this is not the whole story


Effect on the general shape of the spectrum


Resolution (FWHM) ?

Reference at 0 T: • 8,2 (3) keV for 481 keV• 9,7 (6) keV for 975 keV


Resolution (FWHM) ?


not ideal

Noise conditionsor/and

the detector ?


Resolution (FWHM) ?


For 0,5 T: • 10,4 (3) keV for 481 keV• 11,4 (5) keV for 975 keV


Resolution (FWHM) ?



In higher fields the resolution is on average ca. 1 keV worse

Time (arb units)

Resolu

tion (

arb

units)

0,5 T

11 T


Resolution (FWHM) ?



In higher fields the resolution is on average ca. 1 keV worse

Resolution sometimes changed with 1 or 2 keV

→ No 1 to 1 relation with the size of the field→ Clear correlation between the resolution and the noise level


Ghost peaks5 T 7 T


Ghost peaks

419 keV

863 keV

1139 keV

1263 keV

1539 keV

1628 keV

2031 keV


Ghost peaks

419 keV

863 keV

1139 keV

1263 keV

1539 keV

1628 keV

2031 keV

Trapped charges?

Do not go away by lowering the field (or powering down the

detector).We measured at 11 T without this

effect.At 2 T they appeared after 11 hours without clear reason.

→ No clear relation with the size of the field.


Ghost peaks

Trapped charges?

Do not go away by lowering the field (or powering down the

detector).We measured at 11 T without this

effect.At 2 T they appeared after 11 hours without clear reason.

→ No clear relation with the size of the field.

When they dissappeared it always could be linked to some

manipulation of the setup.(Filling of the cryostat which

gives strong vibrations)

There is a clear correlation between the noise level and this

effect.


Ghost peaks

Round up

• The silicon PIN photodiode is a suitable detector

for α and β particles.• Works well at 4 K and ca. 0,5 T

• It survives and works at high magnetic fields up to11 T

• BUT

• Low cost alternative to other solid state particledetectors

Trapped charges? → Forward bias

Future plans

• Test an IC pre-amplifier to reduce noise pick-up

between between the detector and thepre-amplifier and try to cool it together with the

detector• Read out a scintillator and scintillating fiber with a

a photodiode (and maybe switch to an APD).

• More field tests

Attenuation X-ray in Si

From datasheet

From datasheet

2T

Array detector

Si drift

fieldmap

HPGe vs PIN-diode

HPGe

Larmor radius

Documents

Performance of a Si PIN photodiode at low temperatures and in high magnetic fields · 2007. 4. 16. · High field measurements The behaviour of the detector in magnetic fields up