Performance of a Si PIN photodiode at low temperatures and in high magnetic fields

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1 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)

2 Overview The detector and it s usage General properties Tests towards the use in a LTNO setup High field measurements Round up Future plans

3 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: S from HAMAMATSU

4 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: S from HAMAMATSU Light detection * Read out of scintillators! Light level has to be high enough * Datasheet Hamamatsu

5 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: S from HAMAMATSU Light detection * X-ray detection ** High efficiency for low energy`s (< 10 kev)! Noise threshold *Datasheet Hamamatsu ** Y. Inoue et al NIMA 368 (1996)

6 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: S from HAMAMATSU Light detection * X-ray detection ** α-ray detection Thin front dead layer! Radiation damage *Datasheet Hamamatsu ** Y. Inoue et al NIMA 368 (1996)

7 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: S from HAMAMATSU Light detection * electron detection 60 Co *Datasheet Hamamatsu ** Y. Inoue et al NIMA 368 (1996) X-ray detection ** α-ray detection Fully stop energy`s < 350 kev Low background from high energy γ`s

8 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: S from HAMAMATSU Light detection * electron detection 60 Co *Datasheet Hamamatsu ** Y. Inoue et al NIMA 368 (1996) X-ray detection ** α-ray detection Fully stop energy`s < 350 kev Low background from high energy γ`s

9 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

10 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 Dark current drops fast with decreasing temperature Even a little bit of cooling can decrease the detector noise

11 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 * The insensitive surface layer (SiO 2 ) was measured with α-particles: 0,35 µm ± 0,02 µm * Important for measurements with α-particles and low energy X-rays * Y. Atimoto et al., NIMA 557 (2006)

12 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 ** 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. ** Collimator ** A. Simon et al., NIMB 231 (2005)

13 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 compton background. Be able to work close to 4K. Be able to work in magnetic fields up to 0,5 T Standard setup: On the scope Vacuum chamber/ cryostat Pre-amplifier (Canberra 2003) Shaping amplifier 1 or 2 µs shaping time ADC DAQ PC

14 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 compton background. Be able to work close to 4K. Be able to work in magnetic fields up to 0,5 T α`s and β`s at room temperature: 207 Bi source X-rays Pulser 482 kev (K line) 554 kev & 566 kev (L & M line) 976 kev (K line) Typical resolution at 6 MeV is 20 kev, best is 14 kev. Resolution: 6,5 kev 7,1 kev Noise threshold at 23 kev

15 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 compton background. Be able to work close to 4K. Be able to work in magnetic fields up to 0,5 T α`s and β`s at room temperature: 207 Bi measurend with different bias voltages 482 kev (K line) From 30 V on, no big changes in the peakshape. Standard bias: 140 V

16 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 compton background. 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 : Room temperature Liquid nitrogen Liquid helium & 0,5 T

17 Tests towards the use in a LTNO setup 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 60 Co Half-life measurements of α-emittors at low temperatures in metals

18 Tests towards the use in a LTNO setup Our conclusions until now: 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)

19 Tests towards the use in a LTNO setup Our conclusions until now: 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 Temperature cycles Radiation damage

20 Tests towards the use in a LTNO setup Our conclusions until now: 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 The detector is quite sensitive to vibrations (LN 2 filling) Bringing the unamplified signal outside the setup is not optimal noise

21 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) ** S.U. Pandey et al., NIMA 383 (1996) *** A. Castoldi et al., NIMA 399 (1997)

22 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. 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 B 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 T this over a period of two weeks.

23 High field measurements Experimental setup Room temperature shield 77 K 4 K Superconduction magnet up to 17 T Source ( 207 Bi/ 57 Co) PIN diode Usual position of the detector Charge sensitive pre-amplifier DAQ ADC Amplifier

24 High field measurements Experimental setup

25 High field measurements The detector still works even in a magnetic field up to 11 T. General conclusion: The performance of the detector after the field measurent did not go down.

26 High field measurements The detector still works even in a magnetic field up to 11 T. General conclusion:! BUT! this is not the whole story The performance of the detector after the field measurent did not go down.

27 High field measurements Effect on the general shape of the spectrum

28 High field measurements Resolution (FWHM)? Reference at 0 T: 8,2 (3) kev for 481 kev 9,7 (6) kev for 975 kev

29 High field measurements Resolution (FWHM)? Reference at 0 T: 8,2 (3) kev for 481 kev 9,7 (6) kev for 975 kev not ideal Noise conditions or/and the detector?

30 High field measurements Resolution (FWHM)? Reference at 0 T: 8,2 (3) kev for 481 kev 9,7 (6) kev for 975 kev For 0,5 T: 10,4 (3) kev for 481 kev 11,4 (5) kev for 975 kev

31 High field measurements Resolution (FWHM)? Reference at 0 T: 8,2 (3) kev for 481 kev 9,7 (6) kev for 975 kev For 0,5 T: 10,4 (3) kev for 481 kev 11,4 (5) kev for 975 kev In higher fields the resolution is on average ca. 1 kev worse Resolution (arb units) 0,5 T 11 T Time (arb units)

32 High field measurements Resolution (FWHM)? Reference at 0 T: 8,2 (3) kev for 481 kev 9,7 (6) kev for 975 kev For 0,5 T: 10,4 (3) kev for 481 kev 11,4 (5) kev for 975 kev 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

33 High field measurements Ghost peaks 5 T 7 T

34 High field measurements Ghost peaks 419 kev 863 kev 1139 kev 1263 kev 1628 kev 1539 kev 2031 kev

35 High field measurements Ghost peaks Trapped charges? 419 kev 863 kev 1139 kev 1263 kev 1628 kev 1539 kev 2031 kev 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.

36 High field measurements Ghost peaks Trapped charges? 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. 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.

37 High field measurements Ghost peaks

38 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 to 11 T BUT Trapped charges? Forward bias Low cost alternative to other solid state particle detectors

39 Future plans Test an IC pre-amplifier to reduce noise pick-up between between the detector and the pre-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

40 Attenuation X-ray in Si

41 From datasheet

42 From datasheet

43 2T

44 Array detector

45 Si drift

46 fieldmap

47 HPGe vs PIN-diode

48 HPGe

49 Larmor radius