Dr Annika Lohstroh
Senior Lecturer
Qualifications: Dipl. Phys., PhD, PGCAP
Email: a.lohstroh@surrey.ac.uk
Phone: Work: 01483 68 9419
Room no: 17 BB 03
Further information
Biography
Annika Lohstroh grew up in central Germany, where she studied for her undergraduate Diploma in Physics at Göttingen University. She developed an interest in nuclear solid state physics during a 6 month exchange programme with the Catholic University Louvain (Belgium). Subsequently, she continued to study this area of physics that uses techniques originating in nuclear physics to investigate semiconductor properties, like hyperfine interaction methods and ion beam analysis. She moved to Guildford during Summer 2002 and obtained her PhD at the University of Surrey, researching charge transport properties in wide band gap semiconductors for radiation detection applications, with a particular emphasis on chemical vapour deposited diamond. She extended these studies as a Research Fellow at the University of Surrey during the following years and was appointed as Lecturer in 2008. Her scientific aim is to understand the limitations of current radiation detector performance and to find ways to overcome these limits.
Dr Lohstroh is currently (2010-2013) the Chair of the Radiation Detection Instrumentation Research Theme of SEPnet (South East Physics Network).
Research Interests
Research and development of solid state sensors for ionizing radiation, in particular
- the effect of bulk and surface defects on sensor performance.
- the effect of electrode materials and processing for semiconductor detectors
- development of pulse shape analysis for research and applications
Current investigation include
- Development of fast timing detectors based in polycrystalline electronic grade diamond
- Single crystal diamond for particle detection and X-ray dosimetry
- SiC for particle detection - including neurtrons
- Cadmium(Zinc)Telluride for high energy X-ray detection
- HgI2 and TlBr for high energy X-ray detection
- Properties and applications for Silicon Photomultiplier diodes in combination with scintillators, particularly for fast timing.
Publications
Highlights
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(2012) 'Development of large area polycrystalline diamond detectors for fast timing application of high-energy heavy-ion beams'. Institute of Physics Journal of Instrumentation, 7 (5) Article number P05005 Full text is available at: http://epubs.surrey.ac.uk/712259/
Abstract
We have studied the effects of electrode fabrication and detector capacitance on the time resolution of large area electronic grade polycrystalline chemical vapour deposited diamond sensors that are suitable for time of flight measurements of heavy ions at relativistic velocities. Sensors were prepared both in house, with Al or Au metal contacts, and commercially fabricated with Au/diamond-like carbon contacts. He, Ar and a mixture of Ne and O beams at 16.3, 33.5 and 21-23 MeV/u, respectively were used on these devices whilst arranged in transmission geometry. Signal processing only began over one meter away from the sensors. The present approach, where we have large-area/large capacitance multi-strip detectors with processing electronics at some distance from the target, is compatible with anticipated space limitations in particle- identification and tracking setups at existing and planned nuclear fragmentation facilities. In a systematic study under these conditions, we demonstrate that the time resolution is limited by detector capacitance and energy deposition in the sensors. An intrinsic time resolution σ = (44±5) ps was achieved for a diamond detector of ∼ 14 pF capacitance. We conclude that, once further refinements are made, a large area time of flight detection system using polycrystalline diamond detectors would be able to provide time resolutions better than 40 ps, approaching the requirement for particle-identification in relativistic fragmentation experiments, such as those at the facility for antiproton and ion research, FAIR. © 2012 IOP Publishing Ltd and Sissa Medialab srl.
- . (2010) 'Investigation of the internal electric field distribution under in situ x-ray irradiation and under low temperature conditions by the means of the Pockels effect'. IOP PUBLISHING LTD JOURNAL OF PHYSICS D-APPLIED PHYSICS, 43 (8) Article number ARTN 085102
- . (2009) 'Low temperature time of flight mobility measurements on synthetic single crystal diamond'. ELSEVIER SCIENCE SA DIAMOND AND RELATED MATERIALS, 18 (11), pp. 1338-1342.
- .
(2009) 'Comparison of the x-ray spectroscopy response and charge transport properties of semi-insulating In/Al doped CdZnTe crystals'. AMER INST PHYSICS JOURNAL OF APPLIED PHYSICS, 105 (8) Article number ARTN 083101 doi: 10.1063/1.3097301Full text is available at: http://epubs.surrey.ac.uk/102451/
Journal articles
- . (2012) 'A study of timing properties of Silicon Photomultipliers'. Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 695, pp. 257-260.
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(2012) 'Development of large area polycrystalline diamond detectors for fast timing application of high-energy heavy-ion beams'. Institute of Physics Journal of Instrumentation, 7 (5) Article number P05005 Full text is available at: http://epubs.surrey.ac.uk/712259/
Abstract
We have studied the effects of electrode fabrication and detector capacitance on the time resolution of large area electronic grade polycrystalline chemical vapour deposited diamond sensors that are suitable for time of flight measurements of heavy ions at relativistic velocities. Sensors were prepared both in house, with Al or Au metal contacts, and commercially fabricated with Au/diamond-like carbon contacts. He, Ar and a mixture of Ne and O beams at 16.3, 33.5 and 21-23 MeV/u, respectively were used on these devices whilst arranged in transmission geometry. Signal processing only began over one meter away from the sensors. The present approach, where we have large-area/large capacitance multi-strip detectors with processing electronics at some distance from the target, is compatible with anticipated space limitations in particle- identification and tracking setups at existing and planned nuclear fragmentation facilities. In a systematic study under these conditions, we demonstrate that the time resolution is limited by detector capacitance and energy deposition in the sensors. An intrinsic time resolution σ = (44±5) ps was achieved for a diamond detector of ∼ 14 pF capacitance. We conclude that, once further refinements are made, a large area time of flight detection system using polycrystalline diamond detectors would be able to provide time resolutions better than 40 ps, approaching the requirement for particle-identification in relativistic fragmentation experiments, such as those at the facility for antiproton and ion research, FAIR. © 2012 IOP Publishing Ltd and Sissa Medialab srl.
- . (2012) 'Digital pulse height correction in HgI 2 γ-ray detectors'. Elsevier Journal of Instrumentation, 7 (4) Article number T04002
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(2012) 'The X-ray detection performance of polycrystalline CVD diamond with pulsed laser deposited carbon electrodes'. Elsevier Diamond and Related Materials, 22, pp. 70-76.Full text is available at: http://epubs.surrey.ac.uk/712266/
Abstract
The deposition of amorphous carbon electrical contacts on a diamond radiation detector by Pulsed Laser Deposition (PLD) is introduced as a novel technique for producing tissue equivalent X-ray dosimeters. Three devices were fabricated with the following electrical contacts: pure amorphous carbon (labelled Poly-C), amorphous carbon mixed with Nickel (PLD) (labelled Poly-C/Ni) and conventional sputtered Pt (labelled Poly-Pt). To examine the performance of PLD carbon as a contact, a set of X-ray detection characteristics was studied and compared to those of Poly-Pt. This investigation includes current–voltage characteristics, linearity and dose rate dependence, sensitivity and specific sensitivity, photoconductive gain, stability, reproducibility and time response (rise and fall-off times). The experimental results suggest that Poly-C/Ni is suitable for an X-ray dosimeter. It shows a high signal to noise ratio (SNR) of ~ 3300, approximately linear relationship between the photocurrent and the dose rate and a sensitivity of 65 nC/Gy. In addition the current signal is stable and reproducible (within 0.26%) and the rise and fall-off times are less than 1.1 and 0.4 s, respectively.
- . (2011) 'Ion Beam Analysis: A Century of Exploiting the Electronic and Nuclear Structure of the Atom for Materials Characterisation'. World Scientific Reviews of Accelerator Science and Technology, 4, pp. 41-82.
- . (2011) 'The effect of annealing on the X-ray induced photocurrent characteristics of CVD diamond radiation detectors with different electrical contacts'. WILEY-BLACKWELL PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, 208 (9), pp. 2079-2086.
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(2011) 'A study of timing properties of Silicon Photomultipliers'. Elsevier Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Full text is available at: http://epubs.surrey.ac.uk/63080/
Abstract
Silicon Photomultipliers (SiPM) are solid-state pixelated photodetectors. Lately these sensors have been investigated for Time of Flight Positron Emission Tomography (ToF-PET) applications, where very good coincidence time resolution of the order of hundreds of picoseconds imply spatial resolution of the order of cm in the image reconstruction. The very fast rise time typical of the avalanche discharge improves the time resolution, but can be limited by the readout electronics and the technology used to construct the device. In this work the parameters of the equivalent circuit of the device that directly affect the pulse shape, namely the quenching resistance and capacitance and the diode and parasitic capacitances, were calculated. The mean rise time obtained with different preamplifiers was also measured.
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(2010) 'The effect of fast neutron irradiation on the performance of synthetic single crystal diamond particle detectors'. ELSEVIER SCIENCE SA DIAMOND AND RELATED MATERIALS, Athens, GREECE: 19 (7-9), pp. 841-845.Full text is available at: http://epubs.surrey.ac.uk/7672/
- . (2010) 'Investigation of the internal electric field distribution under in situ x-ray irradiation and under low temperature conditions by the means of the Pockels effect'. IOP PUBLISHING LTD JOURNAL OF PHYSICS D-APPLIED PHYSICS, 43 (8) Article number ARTN 085102
- .
(2010) 'Chemical etching and surface oxidation studies of cadmium zinc telluride radiation detectors'. WILEY-BLACKWELL SURFACE AND INTERFACE ANALYSIS, Antalya, TURKEY: 42 (6-7), pp. 795-798.doi: 10.1002/sia.3146
- . (2009) 'Low temperature time of flight mobility measurements on synthetic single crystal diamond'. ELSEVIER SCIENCE SA DIAMOND AND RELATED MATERIALS, 18 (11), pp. 1338-1342.
- .
(2009) 'Comparison of the x-ray spectroscopy response and charge transport properties of semi-insulating In/Al doped CdZnTe crystals'. AMER INST PHYSICS JOURNAL OF APPLIED PHYSICS, 105 (8) Article number ARTN 083101 doi: 10.1063/1.3097301Full text is available at: http://epubs.surrey.ac.uk/102451/
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(2008) 'Ion Beam Induced Charge Studies of CdZnTe Grown by Modified Vertical Bridgman Method'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON NUCLEAR SCIENCE, 55 (6), pp. 3741-3745.Full text is available at: http://epubs.surrey.ac.uk/369/
- . (2008) 'Ion beam induced charge (IBIC) irradiation damage study in synthetic single crystal diamond using 2.6 MeV protons'. WILEY-V C H VERLAG GMBH PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, 205 (9), pp. 2211-2215.
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(2007) 'Mapping of polarization and detrapping effects in synthetic single crystal chemical vapor deposited diamond by ion beam induced charge imaging'. AMER INST PHYSICS JOURNAL OF APPLIED PHYSICS, 101 (6) Article number ARTN 063711 doi: 10.1063/1.2653669Full text is available at: http://epubs.surrey.ac.uk/712332/
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(2007) 'Effect of dislocations on charge carrier mobility-lifetime product in synthetic single crystal diamond'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 90 (10) Article number ARTN 102111 doi: 10.1063/1.2711754Full text is available at: http://epubs.surrey.ac.uk/712333/
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(2006) 'Temperature-dependent hole detrapping for unprimed polycrystalline chemical vapor deposited diamond'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 88 (2) Article number ARTN 023501 doi: 10.1063/1.2162673Full text is available at: http://epubs.surrey.ac.uk/244/
- . (2005) 'Alpha particle transient response of a polycrystalline diamond detector'. PERGAMON-ELSEVIER SCIENCE LTD CARBON, 43 (15), pp. 3167-3171.
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(2005) 'Drift mobility and mobility-lifetime products in CdTe : Cl grown by the travelling heater method'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON NUCLEAR SCIENCE, 52 (6), pp. 3074-3078.Full text is available at: http://epubs.surrey.ac.uk/177/
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(2005) 'Performance improvement of polycrystalline diamond ultraviolet photodetectors by room-temperature plasma treatment'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 86 (9) Article number ARTN 093503 doi: 10.1063/1.1868862Full text is available at: http://epubs.surrey.ac.uk/133/
- . (2005) 'Pulse shape study of chemical vapor deposited diamond alpha particle detectors'. Materials Research Society Symposium Proceedings, 828, pp. 369-374.
- . (2004) 'Digital IBIC-new spectroscopic modalities for ion-beam-induced charge imaging'. ELSEVIER SCIENCE BV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 521 (2-3), pp. 600-607.
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(2004) 'High-resolution mapping of the mobility-lifetime product in CdZnTe using a nuclear microprobe'. IOP PUBLISHING LTD JOURNAL OF PHYSICS-CONDENSED MATTER, LILLE, FRANCE: 16 (2) Article number PII S0953-8984(04)66803-2 , pp. S67-S73.Full text is available at: http://epubs.surrey.ac.uk/712338/
- . (2004) 'Lithium insertion into In2S3 studied by perturbed gamma-gamma angular correlation'. ACADEMIC PRESS INC ELSEVIER SCIENCE JOURNAL OF SOLID STATE CHEMISTRY, 177 (1), pp. 109-118.
Conference papers
- . (2009) 'Real-time imaging of the electric field distribution in CdZnTe at low temperature'. Materials Research Society Symposium Proceedings, San Francisco, USA: MRS 2009 Spring Meeting Symposium L: Nuclear Radiation and Detection of Materials 1164, pp. 15-24.
- . (2008) 'Ion beam induced charge imaging of charge transport in CdTe and CdZnTe'. ELSEVIER SCIENCE BV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, Univ Hyderabad, Sch Phys, Hyderabad, INDIA: 18th International Conference on Ion Beam Analysis 266 (8), pp. 1300-1306.
- . (2007) 'High gain observed in X-ray induced currents in synthetic single crystal diamonds'. WILEY-V C H VERLAG GMBH PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, Hasselt Univ, Diepenbeek-Hasselt, BELGIUM: 12th Hasselt Diamond Workshop 2007 (SBDD XII) 204 (9), pp. 3011-3016.
- . (2007) 'Charge transport in polycrystalline and single crystal synthetic diamond using ion beam induced charge imaging'. ELSEVIER SCIENCE BV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, Singapore, SINGAPORE: 10th International Conference on Nuclear Microprobe Technology and Applications held in Conjunction with the 2nd International Workshop on Proton Beam Writing 260 (1), pp. 293-298.
- . (2007) 'X-ray spectroscopy and charge transport properties of CdZnTe grown by the vertical Bridgman method'. ELSEVIER SCIENCE BV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Pisa, ITALY: 8th International Workshop on Radiation Imaging Detectors 576 (1), pp. 90-94.
- . (2007) 'EBIC and IBIC imaging on polyerystalline CdTe'. ELSEVIER SCIENCE BV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Pisa, ITALY: 8th International Workshop on Radiation Imaging Detectors 576 (1), pp. 5-9.
- . (2007) 'IBIC characterization of charge transport in CdTe : Cl'. MAIK NAUKA/INTERPERIODICA/SPRINGER SEMICONDUCTORS, St Petersburg, RUSSIA: 8th International Workshop on Beam Injection Assessment of Microstructures in Semiconductors 41 (4), pp. 395-401.
- . (2007) 'alpha Particle response of undoped CdMnTe'. ELSEVIER SCIENCE BV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Univ Liverpool, Liverpool, ENGLAND: 7th International Conference on Position-Senstive Detectors 573 (1-2), pp. 220-223.
- . (2005) 'Spatial uniformity of electron charge transport in high resistivity CdTe'. ELSEVIER SCIENCE BV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Univ Glasgow, Glasgow, SCOTLAND: 6th International Workshop on Radiation Imaging Detectors 546 (1-2), pp. 192-199.
- . (2005) 'The effects of plasma post-treatment on the photoresponsivity of CVD diamond UV photodetectors'. ELSEVIER SCIENCE SA DIAMOND AND RELATED MATERIALS, Riva del Garda, ITALY: 15th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides, and Silicon Carbide 14 (3-7), pp. 541-545.
- . (2005) 'The fabrication and performance of CVD diamond-based X-ray detectors'. TRANS TECH PUBLICATIONS LTD PRICM 5: THE FIFTH PACIFIC RIM INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS AND PROCESSING, PTS 1-5, Beijing, PEOPLES R CHINA: 5th Pacific Rim International Conference on Advanced Materials and Processing 475-479, pp. 3605-3609.
- . (2004) 'Ion beam induced charge imaging of epitaxial GaN detectors'. ELSEVIER SCIENCE BV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Riga, LATVIA: 5th International Workshop on Radiation Imaging Detectors 531 (1-2), pp. 82-86.
- . (2004) 'IBIC imaging of intra-crystallite charge transport in CVD diamond at reduced temperature'. ELSEVIER SCIENCE BV NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, Albuquerque, NM: 16th International Conference on Ion Beam Analysis 219, pp. 1022-1026.
- . (2004) 'Electronic relaxation in indium oxide films studied with perturbed angular correlations'. SPRINGER HYPERFINE INTERACTIONS, Bonn, GERMANY: Joint Meeting of the 13th International Conference on Hyperfine Interactions/17th International Symposium on Nuclear Quadrupole Interactions (HFI/NQI 2004) 159 (1-4), pp. 35-42.
- . (2004) 'The role of defects on CdTe detector performance'. IEEE 2003 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-5, Portland, OR: IEEE Nuclear Science Symposium/Medical Imaging Conference, pp. 3306-3310.
- . (2003) 'Ion beam indneed charge microscopy imaging of CVD diamond'. IOP PUBLISHING LTD MICROSCOPY OF SEMICONDUCTING MATERIALS 2003, Univ Cambridge, Cambridge, ENGLAND: Conference on Microscopy of Semiconducting Materials (180), pp. 449-452.
- . (2001) 'Lattice location studies of indium in Cr2O3'. KLUWER ACADEMIC PUBL HYPERFINE INTERACTIONS, PARK CITY, UTAH: 12th International Conference on Hyperfine Interactions 136, pp. 607-612.
- . (2001) 'Lithium in In2S3'. KLUWER ACADEMIC PUBL HYPERFINE INTERACTIONS, PARK CITY, UTAH: 12th International Conference on Hyperfine Interactions 136, pp. 479-484.
Book chapters published:
• Lohstroh, “Radiation Effects Microscopy” published in “Characterisation of Materials”, John Wiley and Sons, published online Oct 2012, DOI: 10.1002/0471266965.com089.pub2
Teaching
- 1st year undergraduate laboratory
- 1st year lecture course "Oscillations and Waves"
- 2nd year lecture course "Radiation detection and measurement" (2009 to 2012)
- Coordination of MSc group projects
- (Part of the) Postgraduate tutorial for new PhD students in Detector physics
- Supervision of Final Year Projects/MPhys/MSc projects/PhD/EngD projects
- Outreach talks - "Nuclear Physics - and what diamonds have to do with it"
Departmental Duties
- Director of the MSc Physics (Euro Master) and MSc in Medical Physics (Euro Master)
- Chair of the Juno Committee
- Departmental Erasmus/Sokrates and Student Exchange coordinator
- Member of the University's Athena Swan Self Assessment team
- Chair of the South East Physics Network (SEPnet) Radiation Detection and Instrumentation (RDI) theme
Invited presentations
• 20th to 25th July 2008, (Technically invited), 11th International Conference on Nuclear Microprobe Technology and Applications (ICNMTA), Debrecen 2008, A. Lohstroh, P. J. Sellin, S. Gkoumas, J. M. Parkin, P. Veeramani, G. Prekas, M. C. Veale, and J. Morse, “Radiation damage study of synthetic single crystal diamond using a 2.6 MeV proton microbeam”
• 7th to 10th May 2012 (invited), 2nd RBI Detector Workshop, Diamond Detectors - Development and Applications: A. Lohstroh, S Gkoumas, P.R. Edwards, F. Schirru, and P. J. Sellin, “Effect of fast neutrons on the performance of diamond detectors” (invited)
• 2nd to 4th April 2012 (invited), Institute of Physics Nuclear Physics conference, Brighton, UK, A.Lohstroh, “Synthetic diamond for charged particle detection”
