1. |
- Rofors, E., et al.
(author)
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Response of a Li-glass/multi-anode photomultiplier detector to focused proton and deuteron beams
- 2020
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 984
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Journal article (peer-reviewed)abstract
- The response of a position-sensitive Li-glass based scintillation detector being developed for thermal-neutron detection with 6 mm position resolution has been investigated using focused beams of 2.5MeV protons and deuterons. The beams were scanned across the detector in 0.5 mm horizontal and vertical steps perpendicular to the beams. Scintillation light was registered using an 8 × 8 pixel multi-anode photomultiplier tube. The signal amplitudes were recorded for each pixel on an event-by-event basis. Several pixels generally registered considerable signals at each beam location. To optimize planned detector operation at the European Spallation Source, the number of pixels above set thresholds was investigated, with the maximization of the single-hit efficiency over the largest possible area as the primary goal. For both beams, at a threshold of ∼50% of the mean of the full-deposition peak, ∼80% of the events were registered in a single pixel, resulting in an effective position resolution of ∼5 mm in X and Y. Lower thresholds resulted in higher pixel multiplicities. These events could also be localized with the same effective position resolution.
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2. |
- Strandberg, B., et al.
(author)
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Near-threshold π-photoproduction on the deuteron
- 2020
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In: Physical Review C. - 2469-9985. ; 101:3
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Journal article (peer-reviewed)abstract
- The first experimental investigation of the near-threshold cross section for incoherent π-photoproduction on the deuteron γd→π-pp is presented. The experimental technique involved detection of the ≈131 MeV γ ray resulting from the radiative capture of photoproduced π-in the target. The total cross section was measured using an unpolarized tagged-photon beam, a liquid-deuterium target, and three very large NaI(Tl) spectrometers. The data are compared to theoretical models that give insight into the elementary reaction γn→π-p and pion-nucleon and nucleon-nucleon final-state interactions.
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3. |
- Rofors, E., et al.
(author)
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Response of a Li-glass/multi-anode photomultiplier detector to collimated thermal-neutron beams
- 2021
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 999
-
Journal article (peer-reviewed)abstract
- The response of a position-sensitive Li-glass scintillator detector being developed for thermal-neutron detection with 6 mm position resolution has been investigated using collimated beams of thermal neutrons. The detector was moved perpendicularly through the neutron beams in 0.5 to 1.0 mm horizontal and vertical steps. Scintillation was detected in an 8 × 8 pixel multi-anode photomultiplier tube on an event-by-event basis. In general, several pixels registered large signals at each neutron-beam location. The number of pixels registering signal above a set threshold was investigated, with the maximization of the single-hit efficiency over the largest possible area of the detector as the primary goal. At a threshold of ∼50% of the mean of the full-deposition peak, ∼80% of the events were registered in a single pixel, resulting in an effective position resolution of ∼5 mm in X and Y. Lower thresholds generally resulted in events demonstrating higher pixel multiplicities, but these events could also be localized with ∼5 mm position resolution.
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4. |
- Messi, F., et al.
(author)
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The neutron-tagging facility at Lund University
- 2020
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In: Modern Neutron Detection : Proceedings of a Technical Meeting - Proceedings of a Technical Meeting. - 1011-4289. - 9789201265203 - 9789201266200 ; :1935, s. 287-297
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Conference paper (other academic/artistic)abstract
- Over the last decades, the field of thermal neutron detection has overwhelmingly employed He-3-based technologies. The He-3 crisis together with the forthcoming establishment of the European Spallation Source have necessitated the development of new technologies for neutron detection. Today, several promising He-3-free candidates are under detailed study and need to be validated. This validation process is in general long and expensive. The study of detector prototypes using neutron-emitting radioactive sources is a cost-effective solution, especially for preliminary investigations. That said, neutron-emitting sources have the general disadvantage of broad, structured, emitted-neutron energy ranges. Further, the emitted neutrons often compete with unwanted backgrounds of gamma-rays, alpha-particles, and fission-fragments. By blending experimental infrastructure such as shielding to provide particle beams with neutron-detection techniques such as tagging, disadvantages may be converted into advantages. In particular, a technique known as tagging involves exploiting the mixed-field generally associated with a neutron-emitting source to determine neutron time-of-flight and thus energy on an event-by-event basis. This allows for the definition of low-cost, precision neutron beams. The Source-Testing Facility, located at Lund University in Sweden and operated by the SONNIG Group of the Division of Nuclear Physics, was developed for just such low-cost studies. Precision tagged-neutron beams derived from radioactive sources are available around-the-clock for advanced detector diagnostic studies. Neutron measurements performed at the Source Testing Facility are thus cost-effective and have a very low barrier for entry. In this paper, we present an overview of the project.
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5. |
- Mauritzson, N., et al.
(author)
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Light-yield response of liquid scintillators using 2–6 MeV tagged neutrons
- 2024
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - 0168-9002. ; 1062
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Journal article (peer-reviewed)abstract
- Knowledge of the neutron light-yield response is crucial to the understanding of scintillator-based neutron detectors. In this work, neutrons from 2–6 MeV have been used to study the scintillation light-yield response of the liquid scintillators NE 213A, EJ 305, EJ 331 and EJ 321P using event-by-event waveform digitization. Energy calibration was performed using a GEANT4 model to locate the edge positions of the Compton distributions produced by gamma-ray sources. The simulated light yield for neutrons from a PuBe source was compared to measured recoil proton distributions, where neutron energy was selected by time-of-flight. This resulted in an energy-dependent Birks parameterization to characterize the non-linear response to the lower energy neutrons. The NE 213A and EJ 305 results agree very well with existing data and are reproduced nicely by the simulation. New results for EJ 331 and EJ 321P, where the simulation also reproduces the data well, are presented.
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6. |
- Mauritzson, N., et al.
(author)
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Light-yield response of liquid scintillators using 2-6 MeV tagged neutrons
- 2024
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 1062
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Journal article (peer-reviewed)abstract
- Knowledge of the neutron light -yield response is crucial to the understanding of scintillator-based neutron detectors. In this work, neutrons from 2-6 MeV have been used to study the scintillation light -yield response of the liquid scintillators NE 213A, EJ 305, EJ 331 and EJ 321P using event -by -event waveform digitization. Energy calibration was performed using a GEANT4 model to locate the edge positions of the Compton distributions produced by gamma -ray sources. The simulated light yield for neutrons from a PuBe source was compared to measured recoil proton distributions, where neutron energy was selected by time -of -flight. This resulted in an energy -dependent Birks parameterization to characterize the non-linear response to the lower energy neutrons. The NE 213A and EJ 305 results agree very well with existing data and are reproduced nicely by the simulation. New results for EJ 331 and EJ 321P, where the simulation also reproduces the data well, are presented.
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7. |
- Mauritzson, N., et al.
(author)
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Technique for the measurement of intrinsic pulse-shape discrimination for organic scintillators using tagged neutrons
- 2022
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 1039
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Journal article (peer-reviewed)abstract
- Fast-neutron/gamma-ray pulse-shape discrimination has been performed for the organic liquid scintillators NE 213A and EJ 305 using a time-of-flight based neutron-tagging technique and waveform digitization on an event-by-event basis. Gamma-ray sources and a Geant4-based simulation were used to calibrate the scintillation-light yield. The difference in pulse shape for the neutron and gamma-ray events was analyzed by integrating selected portions of the digitized waveform to produce a figure-of-merit for neutron/gamma-ray separation. This figure-of-merit has been mapped as a function of detector threshold and also of neutron energy determined from time-of-flight. It shows clearly that the well-established pulse-shape discrimination capabilities of NE 213A are superior to those of EJ 305. The extra information provided by the neutron-tagging technique has resulted in a far more detailed assessment of the pulse-shape-discrimination capabilities of these organic scintillators.
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8. |
- Boyd, L., et al.
(author)
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Simulation of the response of the Solid State Neutron Detector for the European Spallation Source
- 2021
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 998
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Journal article (peer-reviewed)abstract
- The characteristics of the Solid-state Neutron Detector, under development for neutron-scattering measurements at the European Spallation Source, have been simulated with a Geant4-based computer code. The code models the interactions of thermal neutrons and ionising radiation in the 6Li-doped scintillating glass of the detector, the production of scintillation light and the transport of optical, scintillation photons through the scintillator, en route to the photocathode of the attached multi-anode photomultiplier. Factors which affect the optical-photon transport, such as surface finish, pixelation of the glass sheet, provision of a front reflector and optical coupling media are compared. Predictions of the detector response are compared with measurements made with neutron and gamma-ray sources, a collimated alpha source and finely collimated beams of 2.5 MeV protons and deuterons.
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9. |
- Burdeinyi, D. D., et al.
(author)
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Study of C12(γ→,p)11B reactions with polarized photons at energy 40-65 MeV
- 2024
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In: Nuclear Physics A. - 0375-9474. ; 1048
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Journal article (peer-reviewed)abstract
- The photon beam asymmetry of the C12(γ→,p01)11B and C12(γ→,p2−6)11B reactions has been measured in the energy range 40–65 MeV, using a tagged, linearly-polarized photon beam at the MAX-lab facility in Sweden. The asymmetry of the C12(γ→,p01)11B reaction to ground and first excited state of B11 is Σ≈0.82 over the measured energy range. The main contribution to the C12(γ→,p2−6)11B reaction to higher excited states comes from processes in which the residual nucleus is in the 3/2−(5.02 MeV) or 7/2−(6.74 MeV) excited states. The asymmetry of this reaction is Σ≈0.6, close to the value for free deuteron photodisintegration.
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10. |
- Seitz, B., et al.
(author)
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Modern Neutron Detectors with Fast Timing Resolution
- 2020
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In: Modern Neutron Detection : Proceedings of a Technical Meeting - Proceedings of a Technical Meeting. - 1011-4289. - 9789201265203 - 9789201266200 ; :1935, s. 273-277
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Conference paper (other academic/artistic)abstract
- Thermal neutrons are a vital imaging modality with wide ranging applications, exemplified by worldwide endeavours to construct and operate the next generation of accelerator-driven neutron sources with significantly increased neutron flux and, hence, brightness and image contrast. In addition, a high spatial resolution and information about the neutron energy is often desired. The latter is commonly provided by a time-of-flight measurement. These user-driven demands to obtain the best possible image pose significant challenges to the design of the neutron sensor system. The neutron sensor needs to be highly efficient in detecting thermal neutrons, provide the desired spatial and temporal resolution, and has to operate at high count rates. Segmented photon sensors like Multi-Anode Photo Multiplier Tubes (MAPMT) or systems based on Micro Channel Plates (MCP) have been proven in other fields to meet the demands on efficiency, rates, spatial and temporal resolution. Combining these photon sensors with suitable neutron converters, e.g. Lithium-loaded glass scintillators, will provide a neutron detection system capable of meeting the requirements of the next generation of spallation neutron sources. One system based on GS-20 scintillator coupled to a Hamamatsu H12700 MAPMT will be described in detail, as will be the concept of a system based on gadolinium-coated silicon structures coupled to a segmented electron detector.
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