| 1. |
- Akkoyun, S., et al.
(författare)
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AGATA - Advanced GAmma Tracking Array
- 2012
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002 .- 0167-5087 .- 1872-9576. ; 668, s. 26-58
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Tidskriftsartikel (refereegranskat)abstract
- The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation γ-ray spectrometer. AGATA is based on the technique of γ-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a γ ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of γ-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterisation of the crystals was measured and compared with detector- response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximise its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer. © 2011 Elsevier B.V. All rights reserved.
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| 2. |
- Andgren, Karin, et al.
(författare)
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Excited states in the neutron-deficient nuclei Rn-197,Rn-199,Rn-201
- 2008
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 77:5, s. 054303-1-054303-7
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Tidskriftsartikel (refereegranskat)abstract
- Excited states of the extremely neutron-deficient radon isotopes with N = 111, 113, 115 have been studied for the first time in a series of in-beam experiments performed at the Accelerator Laboratory of the University of Jyvaskyla. The reactions used were: Sn-118(Kr-82, 3n)Rn-197, Sn-120(Kr-82, 3n)Rn-199, Sm-150(Cr-52, 3n)Rn-199, and Sn-122(Kr-82, 3n)Rn-201. The gamma rays emitted from excited states in the different isotopes were identified using the recoil-alpha-decay tagging technique. The estimated cross section for the production of Rn-197(m) was 7(3) nb, which is the lowest cross section reported so far for an in-beam study. The energies of the (17/2(+)) levels built on the isomeric (13/2(+)) states in Rn-197,Rn-199,Rn-201 indicate a transition from an anharmonic vibrational structure toward a rotational structure at low spins for these nuclei. However, the transition is not as sharp as predicted by theory.
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| 3. |
- Andgren, Karin, et al.
(författare)
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gamma-ray spectroscopy of At-197
- 2008
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 78:4, s. 044328-1-044328-8
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Tidskriftsartikel (refereegranskat)abstract
- Excited states of the extremely neutron-deficient nucleus At-197 have been studied in an in-beam experiment using the fusion-evaporation reaction Sn-118(Kr-82,p2n)At-197. gamma rays belonging to At-197 feeding the I-pi=(9/2(-)) ground state, as well as gamma rays feeding the 311-keV I-pi=(13/2(+)) isomer, decaying via the emission of gamma rays, and the 52-keV I-pi=(1/2(+)) alpha-decaying isomer have been identified using the recoil-alpha-decay tagging technique. Total Routhian surface calculations predict a near-spherical shape for the (9/2(-)) ground state and oblate shapes with beta(2) around -0.2 for the (1/2(+)) and the (13/2(+)) states. These predictions agree with our experimental findings.
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| 4. |
- Andgren, Karin, et al.
(författare)
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Low-spin collective behavior in the transitional nuclei Mo-86,Mo-88
- 2007
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:1, s. 014307-
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Tidskriftsartikel (refereegranskat)abstract
- Low-spin structures in Mo-86,Mo-88 were populated using the Ni-58(Ar-36, x alpha yp) heavy-ion fusion-evaporation reaction at a beam energy of 111 MeV. Charged particles and gamma rays were emitted in the reactions and detected by the DIAMANT CsI ball and the EXOGAM Ge array, respectively. In addition to the previously reported low-to-medium spin states in these nuclei, new low-spin structures were observed. Angular correlation and linear polarization measurements were performed in order to unambiguously determine the spins and parities of intensely populated states in Mo-88. Quasiparticle Random Phase Approximation (QRPA) calculations were performed for the first and second excited 2(+) states in Mo-86 and Mo-88. The results are in qualitative agreement with the experimental results, supporting a collective interpretation of the low-spin states for these transitional nuclei.
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| 5. |
- Barday, R., et al.
(författare)
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ELECTRON BEAM POLARIMETRY AT LOW ENERGIES AND ITS APPLICATIONS
- 2011
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Ingår i: POLARIZED SOURCES, TARGETS AND POLARIMETRY. - : WORLD SCIENTIFIC PUBL CO PTE LTD. - 9789814324915 - 9789814462747 ; , s. 105-112
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Konferensbidrag (refereegranskat)abstract
- Low energy (E-k similar to 100 keV) Mott scattering polarimetry is a widely established technique to measure the polarization of an electron beam. We analyze the feasibility of Mott scattering at energies up to 20 MeV. For further studies of the electron spin dynamics in the scattering process a correlation between the linear polarization of bremsstrahlung radiation and the electron beam polarization has been measured for the first time using a planar HPGe Compton polarimeter at the 100 keV source of polarized electrons at TU Darmstadt.
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| 6. |
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| 7. |
- Birch, Jens, et al.
(författare)
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(B4C)-B-10 Multi-Grid as an Alternative to He-3 for Large Area Neutron Detectors
- 2013
-
Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 60:2, s. 871-878
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Tidskriftsartikel (refereegranskat)abstract
- Despite its present shortage, He-3 continues to be the most common neutron converter for detectors in neutron scattering science. However, it is obvious that the development of large area neutron detectors based on alternative neutron converters is rapidly becoming a matter of urgency. In the technique presented here, grids each comprising 28 (B4C)-B-10 layers ( each 1 mu m thick) are used to convert neutrons into ionizing particles which are subsequently detected in proportional gas counters. The total active area of the prototype is 8 cm x 200 cm. To instrument this detector 4.6 m(2) of B-10-enriched boron carbide were coated onto aluminium blades using a DC magnetron sputtering machine. Characterization of the prototype showed neutron efficiency to be epsilon(n) = 46.8% for 2.5 angstrom neutrons, which is in line with expectations from MC simulation. This result demonstrates the potential of this technique as alternative to He-3-based position sensitive detectors.
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| 8. |
- Birch, J, et al.
(författare)
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Investigation of background in large-area neutron detectors due to alpha emission from impurities in aluminium
- 2015
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Ingår i: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Thermal neutron detector based on films of (B4C)-B-10 have been developed as an alternative to He-3 detectors. In particular, The Multi-Grid detector concept is considered for future large area detectors for ESS and ILL instruments. An excellent signal-to-background ratio is essential to attain expected scientific results. Aluminium is the most natural material for the mechanical structure of of the Multi-Grid detector and other similar concepts due to its mechanical and neutronic properties. Due to natural concentration of alpha emitters, however, the background from alpha particles misidentified as neutrons can be unacceptably high. We present our experience operating a detector prototype affected by this issue. Monte Carlo simulations have been used to confirm the background as alpha particles. The issues have been addressed in the more recent implementations of the Multi-Grid detector by the use of purified aluminium as well as Ni-plating of standard aluminium. The result is the reduction in background by two orders of magnitude. A new large-area prototype has been built incorporating these modifications.
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| 9. |
- Caceres, L., et al.
(författare)
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Spherical proton-neutron structure of isomeric states in Cd-128
- 2009
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:1, s. 011301-
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Tidskriftsartikel (refereegranskat)abstract
- The gamma-ray decay of isomeric states in the even-even nucleus Cd-128 has been observed. The nucleus of interest was produced both by the fragmentation of Xe-136 and the fission of U-238 primary beams. The level scheme was unambiguously constructed based on.. coincidence relations in conjunction with detailed lifetime analysis employed for the first time on this nucleus. Large-scale shell-model calculations, without consideration of excitations across the N = 82 shell closure, were performed and provide a consistent description of the experimental level scheme. The structure of the isomeric states and their decays exhibit coexistence of proton, neutron, and strongly mixed configurations due to p. interaction in overlapping orbitals for both proton and neutron holes.
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| 10. |
- Cederwall, Bo, et al.
(författare)
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Evidence for a spin-aligned neutron-proton paired phase from the level structure of 92Pd
- 2011
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 469:7328, s. 68-71
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Tidskriftsartikel (refereegranskat)abstract
- Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work(1) that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing(2-6), in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus Pd-92. Gamma rays emitted following the Ni-58(Ar-36,2n)Pd-92 fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction(2-6). We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling(7,8)) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.
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| 11. |
- Cederwall, Bo, et al.
(författare)
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Evidence for enhanced collectivity in Te-I-Xe nuclei near the N=Z=50 double shell closure
- 2007
-
Ingår i: PROTON EMITTING NUCLEI AND RELATED TOPICS. - MELVILLE, USA : AMER INST PHYSICS. - 9780735404755 ; , s. 156-162
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Konferensbidrag (refereegranskat)abstract
- Gamma-ray transitions have been identified for the first time in the extremely neutron-deficient T-z = 1 nuclide Xe-110 and the energies of the three lowest excited states in the ground-state band have been deduced. A level scheme has also been constructed for the proton-unbound, T-z = 3/2 nuclide I-109, exhibiting band structures built on g(7/2) and h(11/2) states in a weakly deformed, triaxial nucleus. In addition, a third band is proposed to be bui It oil a g(7/2) orbital coupled to an octupole-vibrational phonon of the Te-108 core. The results were obtained in a recoil-decay tagging experiment using the Ni-58(Fe-54,2n/p2n) reaction at a beam energy of 195 MeV. The experiment was performed using the highly efficient JUROGAM y-ray spectrometer in conjunction with the RITU gas-filled recoil separator and the GREAT focal -plane spectrometer. The results on Xe-110 establish a breaking of the normal trend of increasing first excited 2(+) and 4(+) level energies as a function of decreasing neutron number as the N = 50 major shell gap is approached for the neutron-deficient Xe isotopes. This unusual feature is suggested to be an effect of enhanced collectivity, possibly arising from isoscalar n-p interactions becoming increasingly important close to the N = Z line. Features in the low-lying levels of Te-106 and I-109, showing similar trends, are also discussed.
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| 12. |
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| 13. |
- Dian, Eszter, et al.
(författare)
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Shielding optimization study for 10b-based large area neutron detectors with detailed geant4 model
- 2017
-
Ingår i: 2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop, NSS/MIC/RTSD 2016. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509016426
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Konferensbidrag (refereegranskat)abstract
- The European Spallation Source (ESS) sets the scope on replacing 3He tube detectors where it is reasonably achievable, consequently advanced neutron detectors require a signal-To-noise (S/N) ratio high enough to be competitive with 3He tubes and satisfy scientific requirements. Advanced local shielding could provide the improved S/N. The objective of the current study is to create a tool that can be used during the shielding optimization process. The study is performed with Monte-Carlo simulations using a Geant4 version extended with NXSG4, that is capable to handle the crystal structure of specific materials, therefore the effects of neutron absorption, coherent and incoherent scattering were simulated. Validation of the extended Geant4 code, developed at ESS is also part of the current study by comparing the simulated results with analytical calculations. A detailed and realistic model of the state-of-The-Art Multi-Grid detector has been implemented, as it is almost the only prototype with published data on scattering effects. Simulations were performed for appropriate shielding materials with various monoenergetic neutron beams.A robust tool has been developed that could be effectively used to arise the S/N via optimizing the detector shielding for specific setups and requirements for all inelastic instruments.
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| 14. |
- Dian, Eszter, et al.
(författare)
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Validation of Detailed Geant4 Model for Thermal Neutron Scattering using the Results of Multi-Grid Detector Prototype Test at CNCS at SNS
- 2017
-
Ingår i: 2017 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC). - : IEEE. - 9781538622827
-
Konferensbidrag (refereegranskat)abstract
- The European Spallation Source (ESS) aspires to be the worlds leading neutron source of the upcoming decades, and sets the scope on replacing He-3 tube detectors where it is reasonably achievable. The Multi-Grid detector, an Ar/CO2-filled proportional chamber based on solid (B4C)-B-10 converter, is the most potent replacement technology for chopper spectroscopy. This study reproduces in a detailed Geant4 geometry of a neutron scattering instrument the data from the Multi-Grid demonstrator detector, that has been tested for a 1 year period, installed side-by-side to the He-3 tubes at the CNCS instrument at SNS. For the further understanding of the background of the detector, Monte-Carlo simulations were performed, with the ESS Coding Framework, using a Geant4 version extended with NXSG4 and NCrystal. A detailed and realistic model of the prototype was built and was validated via comparison against measured data. With this model, different sources of neutron scattering were determined and studied separately, providing a better understanding of the scattered neutron background. Due to these capabilities the model will be used in the further optimization of the detector, especially for the background reduction via shielding, which will lead to instruments with better signal-to-background ratio by design.
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| 15. |
- Dijulio, Douglas D., et al.
(författare)
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Characterization of the radiation background at the Spallation Neutron Source
- 2016
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Ingår i: VI European Conference On Neutron Scattering (ECNS2015). - : IOP Publishing. ; 746:1
-
Konferensbidrag (refereegranskat)abstract
- We present a survey of the radiation background at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, TN, USA during routine daily operation. A broad range of detectors was used to characterize primarily the neutron and photon fields throughout the facility. These include a WENDI-2 extended range dosimeter, a thermoscientific NRD, an Arktis He-4 detector, and a standard Nal photon detector. The information gathered from the detectors was used to map out the neutron dose rates throughout the facility and also the neutron dose rate and flux profiles of several different beamlines. The survey provides detailed information useful for developing future shielding concepts at spallation neutron sources, such as the European Spallation Source (ESS), currently under construction in Lund, Sweden.
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| 16. |
- Ertoprak, Aysegul, et al.
(författare)
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Evidence for octupole collectivity in 172Pt
- 2020
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Ingår i: European Physical Journal A. - : Springer. - 1434-6001 .- 1434-601X. ; 56:2
-
Tidskriftsartikel (refereegranskat)abstract
- Excited states in the extremely neutron-deficient nucleus 172Pt were populated via 96Ru(78Kr,2p) and 92Mo(83Kr,3n) reactions. The level scheme has been extended up to an excitation energy of ~ 5 MeV and tentative spin-parity assignments up to Iπ = 18+. Linear polarization and angular distribution measurements were used to determine the electromagnetic E1 character of the dipole transitions connecting the positive-parity ground-state band with an excited side-band, firmly establishing it as a negative-parity band. The lowest member of this negative-parity structure was firmly assigned spin-parity 3-. In addition, we observed an E3 transition from this 3- state to the ground state, providing direct evidence for octupole collectivity in 172Pt. Large-scale shell model (LSSM) and total Routhian surface (TRS) calculations have been performed, supporting the interpretation of the 3- state as a collective octupole-vibrational state.
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| 17. |
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| 18. |
- Ghazi Moradi, Farnaz, et al.
(författare)
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High-spin study of 162Ta
- 2011
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 84:6, s. 064312-
-
Tidskriftsartikel (refereegranskat)abstract
- Excited states in the odd-odd neutron deficient nucleus (162)Ta (Z = 73, N = 89) have been studied for the first time. The gamma spectroscopy analysis using gamma - gamma - gamma coincidences revealed a strongly coupled rotational structure that was established up to large angular momentum states. The rotational band was assigned to the configuration pi h(11/2)[514]9/2 circle times nu i(13/2)[660]1/2 based on its rotational and electromagnetic properties. The data are interpreted within the framework of total Routhian surface calculations, which suggests an axially symmetric shape with a gamma-softminimum at beta(2) approximate to 0.16 and gamma approximate to 6 degrees. The crossing of the signature partners observed in heavier (N >= 91) odd-odd nuclides in this mass region is found to be absent at N = 89. This might be correlated with a change in S-band structure above the paired band crossing at these neutron numbers.
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| 19. |
- Gorska, M., et al.
(författare)
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Evolution of the N=82 Shell Gap below 132Sn Inferred from Core Excited States in 131In
- 2009
-
Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 672:4-5, s. 313-316
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Tidskriftsartikel (refereegranskat)abstract
- The gamma-ray decay of ail excited state in In-131, the one proton hole neighbor of the doubly magic (132)sn has been measured. A high-spin, core-excited isomer with T-1/2 = 630(60) us was identified following production by both relativistic fragmentation of a Xe-136 beam and fission Of a U-238 beam. This state deexcites by a single gamma-ray branch of 3782(2) keV from which direct evidence for the size of the N = 82 shell gal) is inferred. The results are discussed in comparison to a shell-model Calculation including configurations across the closed shells at N = 82 and Z = 50. (C) 2009 Elsevier B.V. All rights reserved.
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| 20. |
- Hadinia, Baharak, et al.
(författare)
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Identification of gamma rays from Au-172 and alpha decays of Au-172, Ir-168, and Re-164
- 2009
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 80:6, s. 064310-
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Tidskriftsartikel (refereegranskat)abstract
- The very neutron deficient odd-odd nucleus Au-172 was studied in reactions of 342 and 348 MeV Kr-78 beams with an isotopically enriched Ru-96 target. The alpha decays previously reported for Au-172 were confirmed and the decay chain extended down to Tm-152 through the discovery of a new alpha-decaying state in Re-164 [E-alpha=5623(10) keV; t(1/2)=864(-110)(+150) ms; b(alpha)=3(1)%]. Fine structure in these alpha decays of Au-172 and Ir-168 were identified. A new alpha-decaying state was also observed and assigned as the ground state in Au-172 [E-alpha=6762(10) keV; t(1/2)=22(-5)(+6) ms]. This decay chain was also correlated down to Tm-152 through previously reported alpha decays. Prompt gamma rays from excited states in Au-172 have been identified using the recoil-decay tagging technique. The partial level scheme constructed for Au-172 indicates that it has an irregular structure. Possible configurations of the alpha-decaying states in Au-172 are discussed in terms of the systematics of nuclei in this region and total Routhian surface calculations.
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| 21. |
- Hall-Wilton, Richard, et al.
(författare)
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Detectors for the European Spallation Source
- 2012
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Ingår i: 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC). - 1082-3654. ; , s. 4283-4289
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Konferensbidrag (refereegranskat)abstract
- The European Spallation Source (ESS) in Lund, Sweden will become the world's leading neutron source for the study of materials by 2025. First neutrons will be produced in 2019. It will be a long pulse source, with an average beam power of 5 MW delivered to the target station. The pulse length will be 2.86 ms and the repetition rate 14 Hz. The ESS is presently in a design update phase, which ends in February 2013 with a Technical Design Report (TDR). Construction will subsequently start with the goal of bringing the first seven instruments into operation in 2019 at the same time as the source. The full baseline suite of 22 instruments will be brought online by 2025. These instruments present numerous challenges for detector technology in the absence of the availability of Helium-3, which is the default choice for detectors for instruments built until today. Additionally a new generation of source requires a new generation of detector technologies to fully exploit the opportunities that this source provides. This contribution presents briefly the current status of the ESS, and outlines the timeline to completion. The number of instruments and the framework for the decisions on which instruments should be built are shown. For a conjectured full instrument suite, which has been chosen for demonstration purposes for the TDR, a snapshot of the current expected detector requirements is presented. An outline as to how some of these requirements might be tackled is shown. Given that the delivery of the ESS TDR is only a few months away, this contribution reflects strongly the content of the TDR.
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| 22. |
- Höglund, Carina, et al.
(författare)
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B4C thin films for neutron detection
- 2012
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 111:10
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Tidskriftsartikel (refereegranskat)abstract
- Due to the very limited availability of He-3, new kinds of neutron detectors, not based on 3He, are urgently needed. Here, we present a method to produce thin films of (B4C)-B-10, with maximized detection efficiency, intended to be part of a new generation of large area neutron detectors. B4C thin Films have been deposited onto Al-blade and Si wafer substrates by dc magnetron sputtering from (B4C)-B-nat and (B4C)-B-10 targets in an Ar discharge, using an industrial deposition system. The films were characterized with scanning electron microscopy, elastic recoil detection analysis, x-ray reflectivity, and neutron radiography. We show that the film-substrate adhesion and film purity are improved by increased substrate temperature and deposition rate. A deposition rate of 3.8 angstrom/s and substrate temperature of 400 degrees C result in films with a density close to bulk values and good adhesion to film thickness above 3 mu m. Boron-10 contents of almost 80 at. % are obtained in 6.3 m(2) of 1 mu m thick (B4C)-B-10 thin films coated on Al-blades. Initial neutron absorption measurements agree with Monte Carlo simulations and show that the layer thickness, number of layers, neutron wavelength, and amount of impurities are determining factors. The study also shows the importance of having uniform layer thicknesses over large areas, which for a full-scale detector could be in total similar to 1000 m(2) of two-side coated Al-blades with similar to 1 mu m thick (B4C)-B-10 films.
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| 23. |
- Jakobsson, U., et al.
(författare)
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Prompt and delayed spectroscopy of At-199
- 2010
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 82:4, s. 044302-
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Tidskriftsartikel (refereegranskat)abstract
- The neutron-deficient nucleus At-199 has been studied through gamma-ray and electron spectroscopy, using the recoil-decay tagging technique. Two experiments were conducted, using a gas-filled recoil separator with a focal-plane spectrometer alone and together with a germanium-detector array at the target position. The resulting level scheme for 199At includes a new isomer with a half-life of 0.80(5) mu s and a spin and parity of (29/2(+)). The 13/2(+) isomer, which de-excites via an M2 transition to the 9/2 ground state, was measured to have a half-life of 70(20) ns. Our earlier version of the level scheme for At-197 has been updated as well.
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| 24. |
- Kanaki, Kalliopi, et al.
(författare)
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Statistical Energy Determination in Neutron Detector Systems for Neutron Scattering Science
- 2012
-
Ingår i: 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC). - 1082-3654. ; , s. 162-166
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Konferensbidrag (refereegranskat)abstract
- This contribution evaluates the feasibility and potential of a statistical determination of the neutron energy for thermal and cold neutrons in the new generation of neutron detectors. For the European Spallation Source (ESS), sited in Lund, Sweden, which is planned to be operational in 2019, and the world's leading source for the study of materials with neutrons by 2025, novel neutron detectors represent a critical technology that needs to be developed. The discussion here is based upon B-10 based thin-film detectors for neutron scattering science; however such a development is generalisable to other converter materials and potentially relevant to applications outside of neutron scattering science.
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| 25. |
- Khaplanov, Anton, et al.
(författare)
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A gamma-ray polarimeter based on a single segmented planar HPGe detector
- 2008
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 593:3, s. 459-465
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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