Silicon Drift Detectors for

Synchrotron Energy Dispersive X-Ray Fluorescence Spectroscopy

(SDD for EDXRF)

Presentation

by

Dr. Saleh Qutaishat

Petra UniversityAmman – Jordan

Presented at

the ninth SESAME users’ meeting, 12-14 November, Days Inn Hotel, Amman, Jordan

Introduction

Detector description and its principle of operation

Detector module.

Detector Features and its Performance

EDXRF of Fe 55 Spectrum

Summary and Concluding Remarks.

References

Video Clip on SDD applications

Fig. 1.1) X-ray absorptionEnergy of an incident X-ray photon is absorbed by a core-level electron then the electron is ejected from the atom as a Photo-electron.2) X-ray Fluorescence

Higher energy core electron fills an empty electron level , and x-ray of fixed energy is emitted.

2) X-ray Fluorescence Higher energy core electron fills an empty electron level , and an x-ray of fixed

energy is emitted

Fig. 2. Schematic diagram of X-ray detection and signal processing

Fig. 3. Schematic diagram of the SDD.In the detector’s core; incident X-ray interacts with n-Silicon and produces electron-hole pairs. The number of electrons produced are proportional to the energy of the interacting X-ray photon. The electrons move fast towards the anode under the influence of an electric field parallel to the surface of the detector. The anode is connected to the gate of an integrated Field Effect Transistor (FET). Once the electrons reach the anode they produce an electric current signalThe SDD was invented by E. Gatti and P. Rehak in 1983.

207http://www.ketek.net/index.php?id=

Fig. 4. Animation of interaction of X-ray photons with SDD producing electron-hole pairs. Then the electrons are drifted until they reach the anode of the detector.

Fig. 5. Detector Module; a thermoelectrically cooled Silicon Drift Detector (SDD). Also mounted on the 2-stage cooler are the input FET and a novel feedback circuit. These components are kept at approximately -55 °C, and are monitored by an internal temperature sensor. The hermetic TO-8 package of the detector has a light tight, vacuum tight thin Beryllium window to enable soft x-ray detection.

Fig. 6. Block diagram of the SDD module with Peltier cooler and related electronics of (EDXRF) spectroscopy.

Fig. 7. Silicon Drift Detectors (SDD)

Detector Features and its performance

HIGH COUNT RATE - 500,000 CPS

125 eV FWHM Resolution @ 5.9 keV

High Peak-to-Background Ratio - 8200:1

Up to 80mm2 active area X 500 µm thikness

Multilayer Collimator

No Liquid Nitrogen

Fig. 8. Efficiency versus energy graph of Silicon Drift Detector (SDD).

SDD

Fig. 9. Schematic diagram of a Synchrotron. SDD is installed at the end station of X-ray Fluorescence (XRF) beam line BL6b

Fig. 10. Characteristic peaks in Spectrum of Fe55 X-ray source taken by using SDD

http://www.youtube.com/watch?v=l34JUidTbCk&feature=related

Fig. 11. Video clips for the X-MAX Drift Detector (SDD) from Oxford Instruments mounted on a Scanning Tunneling Microscope (STM) and used for elements identification and mapping.

1Video clip Silicon Drift Detector application

2Silicon drift Detector application Video clip

http://www.youtube.com/watch?v=mZsJI9nnK6I

Summary:A Silicon Drift Detector (SDD) was presented. The detector structure and its working principle were explained. The detector is cooled by a Peltier cooling element giving it a great advantage over liquid Nitrogen cooled detectors.

The detection system has a high energy resolution due to the low output capacitance of the SDD and the integration of the FET on the detector. Energy resolution of the system is 125 eV FWHM at 5.9 KeV Fe Kα.

Due to its short time shaping signal SDD has a high count rate of 500,000 counts per second.

SDDs are famous in being used in Synchrotron energy dispersive X-ray fluorescence (EDXRF) spectroscopy and in portable XRF analysis devices.

Concluding Remarks:

The key advantage of the SDD is that it has much lowercapacitance than a conventional SiLi detectors of thesame area, therefore reducing electronic noise at shortshaping times.

For X-ray spectroscopy, an SDD has better energyresolution while operating at much higher count ratesthan a conventional semiconductor.

The SDD uses a special electrode structure to guide theelectrons to a very small, low capacitance anode.

References:[1] E. Gatti, P. Rehak, Semiconductor drift chamber - an application of a novel charge transport scheme, Nucl. Instr. and Meth. 225 (1984) 608-614

[2] J. Kemmer, G. Lutz, New detector concepts, Nucl. Instr. and Meth. A 253 (1987) 365-377

[3] P. Lechner et al., Silicon drift detectors for high resolution room temperature X-ray spectroscopy, Nucl. Instr. and Meth. A 377 (1996) 346-351

[4] Synchrotron Hard X-ray Microbeam Techniques, Antonio Lanzirott, the University of Chicago, Center for Advanced Radiation Source.

[5] http://www.oxinst.com/Campaigns/microanalysis/eds/detectors/large-area-silicon-drift-detector/Pages/x-max-sdd.aspx

[6] Silicon Drift Detector with On-Chip Electronics, for X-Ray SpectroscopyKETEK GmbH, Am Isarbach 30, D-85764 Oberschleißheim, GERMANY.

[7] Energy resolving detectors for X-ray spectroscopy, by J Morse, Detector Unit -ISDD , European Synchrotron Radiation Facility, ESRF, 19-02-2010.

[10] Semiconductor Detectors, physics and practical application issues:H Spieler, ‘Semiconductor Detector Systems’, OUP, 2005G Lutz, ‘Semiconductor Radiation Detectors: Device Physics’, Springer Berlin 1999

[11] G Knoll ‘Radiation Detection and Measurement’, Wiley , 2000

[12] Design of microelectronic thermal detectors for high resolution radiation spectroscopy, S. Qutaishat, P. Davidsson, P. Delsing, B. Jonson, R. Kroc, M. Lindroos, S. Norrman and G. Nyman, Nucl. Instr. and Meth. A342 (1994) 504.

[13] Silicon thermal detectors for single quanta of radiation: fabrication, statistical fluctuations of phonons, physical properties and operation, P. Davidsson, P. Delsing, B. Jonson, R. Kroc, M. Lindroos, S. Norrman, G. Nyman, A. Oberstedt and S. Qutaishat, Nucl. Instr. and Meth. A350 (1994) 250.

[14] Design and implementation of a computer interface for data acquisition in nuclear physics Laboratories, By Saleh Qutaishat, 1986.

[15] Design and development of crystalline thermal detectors for single quanta of radiation and high resolution radiation spectroscopy, by Saleh Qutaishat, Published 1994, ISBN: 9171970126 / 91-7197-012-6.

[8] http://www.pndetector.de/broxDL .

[9] Swiss Light Source SLS and Paul Scherrer Institute Equipment, http://www.psi.ch/sls/optics/equipment

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