| 1. |
- Addazi, A., et al.
(författare)
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New high-sensitivity searches for neutrons converting into antineutrons and/or sterile neutrons at the HIBEAM/NNBAR experiment at the European Spallation Source
- 2021
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Ingår i: Journal of Physics G. - : Institute of Physics Publishing (IOPP). - 0954-3899 .- 1361-6471. ; 48:7
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Tidskriftsartikel (refereegranskat)abstract
- The violation of baryon number, , is an essential ingredient for the preferential creation of matter over antimatter needed to account for the observed baryon asymmetry in the Universe. However, such a process has yet to be experimentally observed. The HIBEAM/NNBAR program is a proposed two-stage experiment at the European Spallation Source to search for baryon number violation. The program will include high-sensitivity searches for processes that violate baryon number by one or two units: free neutron–antineutron oscillation () via mixing, neutron–antineutron oscillation via regeneration from a sterile neutron state (), and neutron disappearance (n → n'); the effective process of neutron regeneration () is also possible. The program can be used to discover and characterize mixing in the neutron, antineutron and sterile neutron sectors. The experiment addresses topical open questions such as the origins of baryogenesis and the nature of dark matter, and is sensitive to scales of new physics substantially in excess of those available at colliders. A goal of the program is to open a discovery window to neutron conversion probabilities (sensitivities) by up to three orders of magnitude compared with previous searches. The opportunity to make such a leap in sensitivity tests should not be squandered. The experiment pulls together a diverse international team of physicists from the particle (collider and low energy) and nuclear physics communities, while also including specialists in neutronics and magnetics.
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| 2. |
- Rofors, E., et al.
(författare)
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Response of a Li-glass/multi-anode photomultiplier detector to focused proton and deuteron beams
- 2020
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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. ; 984
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Backis, A., et al.
(författare)
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Time- and energy-resolved effects in the boron-10 based multi-grid and helium-3 based thermal neutron detectors
- 2021
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Ingår i: Measurement science and technology. - : IOP PUBLISHING LTD. - 0957-0233 .- 1361-6501. ; 32:3
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Tidskriftsartikel (refereegranskat)abstract
- The boron-10 based multi-grid detector is being developed as an alternative to helium-3 based neutron detectors. At the European Spallation Source, the detector will be used for time-of-flight neutron spectroscopy at cold to thermal neutron energies. The objective of this work is to investigate fine time- and energy-resolved effects of the Multi-Grid detector, down to a few mu eV, while comparing it to the performance of a typical helium-3 tube. Furthermore, it is to characterize differences between the detector technologies in terms of internal scattering, as well as the time reconstruction of similar to mu s short neutron pulses. The data were taken at the Helmholtz Zentrum Berlin, where the Multi-Grid detector and a helium-3 tube were installed at the ESS test beamline, V20. Using a Fermi-chopper, the neutron beam of the reactor was chopped into a few tens of mu s wide pulses before reaching the detector, located a few tens of cm downstream. The data of the measurements show an agreement between the derived and calculated neutron detection efficiency curve. The data also provide fine details on the effect of internal scattering, and how it can be reduced. For the first time, the chopper resolution was comparable to the timing resolution of the Multi-Grid detector. This allowed a detailed study of time- and energy resolved effects, as well as a comparison with a typical helium-3 tube.
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| 4. |
- Rofors, E., et al.
(författare)
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Response of a Li-glass/multi-anode photomultiplier detector to collimated thermal-neutron beams
- 2021
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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. ; 999
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Rofors, E., et al.
(författare)
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Response of a Li-glass/multi-anode photomultiplier detector to α-particles from 241 Am
- 2019
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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. ; 929, s. 90-96
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Tidskriftsartikel (refereegranskat)abstract
- The response of a position-sensitive Li-glass scintillator detector to α-particles from a collimated 241 Am source scanned across the face of the detector has been measured. Scintillation light was read out by an 8 × 8 pixel multi-anode photomultiplier and the signal amplitude for each pixel has been recorded for every position on a scan. The pixel signal is strongly dependent on position and in general several pixels will register a signal (a hit) above a given threshold. The effect of this threshold on hit multiplicity is studied, with a view to optimize the single-hit efficiency of the detector.
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| 6. |
- Wildner, E., et al.
(författare)
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The Opportunity Offered by the ESSnuSB Project to Exploit the Larger Leptonic CP Violation Signal at the Second Oscillation Maximum and the Requirements of This Project on the ESS Accelerator Complex
- 2016
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Ingår i: Advances in High Energy Physics. - : Hindawi Publishing Corporation. - 1687-7357 .- 1687-7365.
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Tidskriftsartikel (refereegranskat)abstract
- The European Spallation Source (ESS), currently under construction in Lund, Sweden, is a research center that will provide, by 2023, the world's most powerful neutron source. The average power of the proton linac will be 5 MW. Pulsing this linac at higher frequency will make it possible to raise the average total beam power to 10 MW to produce, in parallel with the spallation neutron production, a very intense neutrino Super Beam of about 0.4 GeV mean neutrino energy. This will allow searching for leptonic CP violation at the second oscillation maximum where the sensitivity is about 3 times higher than at the first. The ESS neutrino Super Beam, ESSnuSB operated with a 2.0 GeV linac proton beam, together with a large undergroundWater Cherenkov detector located at 540 km from Lund, will make it possible to discover leptonic CP violation at 5 sigma. significance level in 56% (65% for an upgrade to 2.5 GeV beam energy) of the leptonic CP-violating phase range after 10 years of data taking, assuming a 5% systematic error in the neutrino flux and 10% in the neutrino cross section. The paper presents the outstanding physics reach possible for CP violation with ESSnuSB obtainable under these assumptions for the systematic errors. It also describes the upgrade of the ESS accelerator complex required for ESSnuSB.
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| 7. |
- Boyd, L., et al.
(författare)
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Simulation of the response of the Solid State Neutron Detector for the European Spallation Source
- 2021
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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. ; 998
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Mauritzson, N., et al.
(författare)
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Light-yield response of liquid scintillators using 2–6 MeV tagged neutrons
- 2024
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - 0168-9002. ; 1062
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Tidskriftsartikel (refereegranskat)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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| 9. |
- Mauritzson, N., et al.
(författare)
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Technique for the measurement of intrinsic pulse-shape discrimination for organic scintillators using tagged neutrons
- 2022
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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. ; 1039
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Tidskriftsartikel (refereegranskat)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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| 10. |
- Rofors, E., et al.
(författare)
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Response of a Li-glass/multi-anode photomultiplier detector to alpha-particles from Am-241
- 2019
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 929, s. 90-96
-
Tidskriftsartikel (refereegranskat)abstract
- The response of a position-sensitive Li-glass scintillator detector to alpha-particles from a collimated Am-241 source scanned across the face of the detector has been measured. Scintillation light was read out by an 8 x 8 pixel multi-anode photomultiplier and the signal amplitude for each pixel has been recorded for every position on a scan. The pixel signal is strongly dependent on position and in general several pixels will register a signal (a hit) above a given threshold. The effect of this threshold on hit multiplicity is studied, with a view to optimize the single-hit efficiency of the detector.
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