Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Position-sensitive germanium detectors for gamma-ray tracking, imaging and polarimetry
KTH, School of Engineering Sciences (SCI), Physics. (Nuclear physics)
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Modern germanium detectors are often manufactured with two-dimensionally segmented electrical contacts. Signals induced in each segment are read out simultaneously when a photon is detected. Detailed pulse shape analysis (PSA) of these signals allows to resolve positions of individual γ-ray interactions with a precision of at least a few mm. The track of a photon can then be reconstructed using γ-ray tracking. Using these techniques, highly efficient large-volume germanium detectors can replace detector systems where previously highly granulated detector arrays were required, and/or large fractions of photons had to be rejected. The ability to reconstruct the direction of an incoming photon and its scattering path makes it possible to use segmented detectors for γ-ray imaging and polarimetry. Doppler correction of photon energies in experiments where γ rays are emitted from fast ion beams can be greatly improved due to improved determination of the emission angle with respect to the beam. Furthermore, arrays of many detectors can be built without the need for conventional anticoincidence detectors for escape suppression. Instead, photons escaping a detector crystal can be tracked through neighbouring ones.

In this work position reconstruction accuracy was evaluated for segmented detectors in a number of geometries in realistic applications. Particular emphasis has been put on the reconstruction of data sets containing events of arbitrary complexity in terms of the number of hit segments and interactions per segment. The imaging and polarization sensitivities of a single planar germanium pixel detector have been evaluated experimentally. In these measurements, photons absorbed in two, often adjacent, segments were reconstructed. Simulated interactions of γ-rays with the detectors of the proposed DESPEC germanium array were analysed yielding the position resolution obtainable in realistic experimental situations, as well as its dependence on photon energy, event complexity, noise and other sources of error.

Place, publisher, year, edition, pages
Stockholm: KTH , 2010. , viii, 88 p.
Series
TRITA-FYS, ISSN 0280-316X ; 2010:04
National Category
Subatomic Physics
Identifiers
URN: urn:nbn:se:kth:diva-11996ISBN: 978-91-7415-555-6 OAI: oai:DiVA.org:kth-11996DiVA: diva2:292814
Public defence
2010-02-26, FB54, Roslagstullsbacken 21, AlbaNova, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20170222

Available from: 2010-02-10 Created: 2010-02-09 Last updated: 2017-02-22Bibliographically approved
List of papers
1. Compton imager based on a single planar segmented HPGe detector
Open this publication in new window or tab >>Compton imager based on a single planar segmented HPGe detector
2007 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 580, 1075-1078 p.Article in journal (Refereed) Published
Abstract [en]

A collimator-free Compton imaging system has been developed based on a single high-purity germanium detector and used to generate images of radioactive sources emitting gamma rays. The detector has a planar crystal with one pixellated contact with a total of 25 segments. Pulse shape analysis has been applied to achieve a 3D-position sensitivity of the detector. The first imaging results from this detector are presented, based on the reconstruction of events where a gamma ray is fully absorbed after scattering between adjacent segments.

Keyword
Compton imaging, gamma-ray imaging, segmented planar germanium detector, pulse shape analysis
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-7861 (URN)10.1016/j.nima.2007.06.065 (DOI)000250128000051 ()2-s2.0-34548487328 (Scopus ID)
Note

QC 20101110

Available from: 2007-12-19 Created: 2007-12-19 Last updated: 2016-12-19Bibliographically approved
2. A gamma-ray polarimeter based on a single segmented planar HPGe detector
Open this publication in new window or tab >>A gamma-ray polarimeter based on a single segmented planar HPGe detector
2008 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, Vol. 593, no 3, 459-465 p.Article in journal (Refereed) Published
Abstract [en]

The polarization sensitivity of a segmented planar HPGe detector has been measured. For this purpose 662 keV photons from a Cs-137 source which were Compton scattered at approximate to 90 degrees in a coaxial germanium detector were utilized as a source of partially linearly polarized gamma radiation of the energy; approximate to 288 keV. The detector has a 50 x 50 x 21 mm sensitive volume and 5 x 5 electrical segmentation of the cathode contact. The degree of linear polarization is determined through the analysis of the directions of Compton scatterings inside the detector. The locations of the Compton scattering interactions and of the subsequent photo-absorption interactions have been determined with the help of pulse shape analysis (PSA), provided that these interactions are in two different segments of the planar detector. A comparison with a polarization analysis using the position resolution defined by the physical segmentation (without the use of PSA) was also performed. It is demonstrated that the use of PSA enables a much higher polarization sensitivity for events where the 288 keV photons scatter between adjacent pixels. Such events constitute 90% of the data for the 288 keV photons and are even more important for gamma-rays of lower energies.

Keyword
polarization, segmented planar germanium detector, pulse shape analysis, matrix method
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-7862 (URN)10.1016/j.nima.2008.05.063 (DOI)000259120700030 ()2-s2.0-47849098320 (Scopus ID)
Note
QC 20101110Available from: 2007-12-19 Created: 2007-12-19 Last updated: 2010-11-10Bibliographically approved
3. Position sensitivity of segmented planar HPGe detectors for the DESPEC project at FAIR
Open this publication in new window or tab >>Position sensitivity of segmented planar HPGe detectors for the DESPEC project at FAIR
2008 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, Vol. 592, 325-333 p.Article in journal (Refereed) Published
Abstract [en]

One of the proposed germanium detector systems for the upcoming DESPEC array at the FAIR facility consists of triple modules of electrically segmented planar high-purity germanium detectors. In this work, the position sensitivity obtained by means of pulse shape analysis (PSA) for simulated gamma-ray interactions has been studied for the possible segmentation patterns for such detectors-the double-sided strip detector (DSSD) and the one-sided pixelated geometry. An over-all similar number of readout channels has been considered for each case, resulting in 8 + 8 strips and 16 pixels. It has been found that the higher physical granularity of the DSSD results in a significantly higher position resolution, as well as in a somewhat lower probability of merging multiple interaction points. A drawback of the DSSD geometry is the inability to assign the interactions to the correct voxels for certain complex multiple interaction patterns. This effect has been studied in detail. Finally, a comparison has been made with the existing 25-pixel planar detector at KTH [A. Khaplanov, et al., Nucl. Instr. and Meth. A 580 (2007) 1075; L. Milechina, B. Cederwall, Nucl. Instr. and Meth. A 550 (2005) 278)].

Keyword
DESPEC, segmented planar germanium detector, pulse shape analysis, matrix method
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-7863 (URN)10.1016/j.nima.2008.03.111 (DOI)000258252500021 ()2-s2.0-46649092130 (Scopus ID)
Note
QC 20101110Available from: 2007-12-19 Created: 2007-12-19 Last updated: 2010-11-10Bibliographically approved
4. Position sensitivity of the proposed segmented germanium detectors for the DESPEC project
Open this publication in new window or tab >>Position sensitivity of the proposed segmented germanium detectors for the DESPEC project
2009 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 604, no 1/2, 56-59 p.Article in journal (Refereed) Published
Abstract [en]

The DESPEC HPGe array is a part of the NuSTAR project at FAIR, Germany. It is aimed at the spectroscopy of the stopped decaying exotic nuclei. Segmented gamma-ray tracking detectors are proposed for this array in order to maximize detection efficiency and background suppression when searching for very rare events. Two types of detector modules-stacks of three 16-fold segmented planar crystals and 12- and 16-fold segmented clover detectors-have been investigated and compared from the point of view of the achievable position resolution using pulse shape analysis (PSA). To this end, detector signals from realistic gamma-ray interactions have been calculated. These signals were treated by PSA in order to reconstruct the photon interaction locations. Comparing the initial interaction locations to the reconstructed ones, it was found that the double-sided strip planar detector yielded position reconstruction errors at least a factor 2 lower than the other detectors considered

Keyword
DESPEC, Segmented germanium detector, Pulse shape analysis, Matrix method
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-11998 (URN)10.1016/j.nima.2009.01.080 (DOI)000267405700017 ()2-s2.0-65749100014 (Scopus ID)
Note
QC 20110211(8th International Conference on Position Sensitive Detectors Univ Glasgow, Glasgow, SCOTLAND, SEP 01-05, 2008) Available from: 2010-02-10 Created: 2010-02-10 Last updated: 2017-12-12Bibliographically approved

Open Access in DiVA

fulltext(3737 kB)698 downloads
File information
File name FULLTEXT01.pdfFile size 3737 kBChecksum SHA-512
352998f701742c88e00bb143934c5eb1c23e737cbee179e0316955b364363ee81a2ee3740d8c2c64a5008f9aa9d0ef451e9f3f86042d43ce59b58c1ee64aec39
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Khaplanov, Anton
By organisation
Physics
Subatomic Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 698 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 339 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf