O. Zimmer, T. Bigault, S. Degenkolb, Christoph Herb, Thomas Neulinger, N. Rizzi, V. Santoro, A. Takibayev, R. Wagner, L. Zanini
This paper discusses design principles and possible performances of an “in-beam” ultracold neutron (UCN) source for the European Spallation Source (ESS). The key components of the proposed neutron delivery system are nested-mirror optics (NMO), which image the bright neutron emission surface of the large liquid-deuterium moderator, studied within the HighNESS project, onto a remotely located superfluid-helium converter. Bandpass supermirrors, with optional polarization capability, enable the selective transport of those neutrons that are most effective for UCN production, exploiting the single-phonon conversion process that is possible for neutrons having wavelengths within a narrow range centered on 8.9 A ˚. NMO are capable of extracting and refocusing neutrons with small transport losses under the large solid angle available at the ESS Large Beam Port (LBP), allowing the converter to be placed far away from the high-radiation area in the ESS shielding bunker, where the source stays accessible for trouble-shooting while facilitating a low-background environment for nearby UCN experiments. Various configurations of the beam and converter are possible, including a large-volume converter – with or without a magnetic reflector – for a large total UCN production rate, or a beam focused onto a small converter for highest possible UCN density. The source performances estimated by first simulations of a baseline version presented in this paper, including a saturated UCN density on the order of 10 5 cm − 3 , motivate further study and the development of NMO beyond the first prototypes that have been recently investigated experimentally.
{"title":"In-beam superfluid-helium ultracold neutron source for the ESS","authors":"O. Zimmer, T. Bigault, S. Degenkolb, Christoph Herb, Thomas Neulinger, N. Rizzi, V. Santoro, A. Takibayev, R. Wagner, L. Zanini","doi":"10.3233/jnr-220045","DOIUrl":"https://doi.org/10.3233/jnr-220045","url":null,"abstract":"This paper discusses design principles and possible performances of an “in-beam” ultracold neutron (UCN) source for the European Spallation Source (ESS). The key components of the proposed neutron delivery system are nested-mirror optics (NMO), which image the bright neutron emission surface of the large liquid-deuterium moderator, studied within the HighNESS project, onto a remotely located superfluid-helium converter. Bandpass supermirrors, with optional polarization capability, enable the selective transport of those neutrons that are most effective for UCN production, exploiting the single-phonon conversion process that is possible for neutrons having wavelengths within a narrow range centered on 8.9 A ˚. NMO are capable of extracting and refocusing neutrons with small transport losses under the large solid angle available at the ESS Large Beam Port (LBP), allowing the converter to be placed far away from the high-radiation area in the ESS shielding bunker, where the source stays accessible for trouble-shooting while facilitating a low-background environment for nearby UCN experiments. Various configurations of the beam and converter are possible, including a large-volume converter – with or without a magnetic reflector – for a large total UCN production rate, or a beam focused onto a small converter for highest possible UCN density. The source performances estimated by first simulations of a baseline version presented in this paper, including a saturated UCN density on the order of 10 5 cm − 3 , motivate further study and the development of NMO beyond the first prototypes that have been recently investigated experimentally.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45810437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Low counting statistics is one of the most important challenges in modern experiments with ultracold neutrons (UCN). UCN densities in superthermal sources based on superfluid helium are normally much higher than those after UCN delivery to ex-situ volumes. Therefore, and due to the vanishing neutron absorption of 4He, storage-based experiments performed in-situ promise significant sensitivity gains. Scalable measurements offer a promising path to simultaneously address the inefficient use of cold neutron beams as precursors for UCN production in 4He, by recuperating the unused beam fraction, and confront the practical challenges of large-scale UCN infrastructure. We suggest strategies for the development of modular cryogenic cells, propose a novel approach for in-situ UCN detection, and discuss the ultimate statistical reach of such a multiplexed experiment for measuring the neutron’s permanent electric dipole moment (EDM). While dedicated research and development are needed to evaluate the feasibility for many requirements, a neutron EDM measurement with sensitivity well beyond 10 − 28 e cm seems possible. Such an experiment could be pursued at any compatible cold neutron beamline, e.g., at the Institut Laue–Langevin, or later using the ANNI facility or large beam port (LBP) at the European Spallation Source.
低计数统计是现代超冷中子实验中最重要的挑战之一。基于超流氦的超热源中的UCN密度通常比UCN输送到非原位体积后的密度高得多。因此，由于4He的中子吸收消失，基于存储的原位实验有望获得显着的灵敏度增益。可扩展的测量提供了一条有希望的途径，通过回收未使用的束流部分，同时解决冷中子束在4He中作为UCN生产前体的低效使用问题，并应对大规模UCN基础设施的实际挑战。我们提出了开发模块化低温电池的策略，提出了一种原位UCN检测的新方法，并讨论了这种用于测量中子永久电偶极矩(EDM)的复用实验的最终统计范围。虽然需要专门的研究和开发来评估许多要求的可行性，但灵敏度远远超过10 - 28 e cm的中子电火花加工测量似乎是可能的。这样的实验可以在任何兼容的冷中子束流线上进行，例如在劳厄-朗格万研究所，或者后来使用ANNI设施或欧洲散裂源的大束流端口(LBP)。
{"title":"Approaches to high-density storage experiments with in-situ production and detection of ultracold neutrons","authors":"S. Degenkolb, P. Fierlinger, O. Zimmer","doi":"10.3233/jnr-220044","DOIUrl":"https://doi.org/10.3233/jnr-220044","url":null,"abstract":"Low counting statistics is one of the most important challenges in modern experiments with ultracold neutrons (UCN). UCN densities in superthermal sources based on superfluid helium are normally much higher than those after UCN delivery to ex-situ volumes. Therefore, and due to the vanishing neutron absorption of 4He, storage-based experiments performed in-situ promise significant sensitivity gains. Scalable measurements offer a promising path to simultaneously address the inefficient use of cold neutron beams as precursors for UCN production in 4He, by recuperating the unused beam fraction, and confront the practical challenges of large-scale UCN infrastructure. We suggest strategies for the development of modular cryogenic cells, propose a novel approach for in-situ UCN detection, and discuss the ultimate statistical reach of such a multiplexed experiment for measuring the neutron’s permanent electric dipole moment (EDM). While dedicated research and development are needed to evaluate the feasibility for many requirements, a neutron EDM measurement with sensitivity well beyond 10 − 28 e cm seems possible. Such an experiment could be pursued at any compatible cold neutron beamline, e.g., at the Institut Laue–Langevin, or later using the ANNI facility or large beam port (LBP) at the European Spallation Source.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42189840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Kino, T. Fujiwara, M. Furusaka, T. Muroga, B. O’Rourke, N. Oshima, Y. Tomota
The neutron wavelength resolution, Bragg-edge measurement ability and future prospects regarding the neutron count rate were investigated at AISTANS. The wavelength resolution evaluated by Bragg-edge analysis using an iron powder sample is in reasonably good agreement with calculations at neutron wavelengths of 0.2–0.3 nm. Bragg-edge imaging was also performed on a steel plate sample with distinct regions of BCC and FCC crystallinity, and the different crystal structures were successfully discriminated. In addition, an aluminum sample containing a friction stir spot welding region was also measured and the 200 and 111 Bragg-edges at the two joining areas were observed. However, it was hard to characterize the difference in texture between the two areas. The neutron counting rate for Bragg-edge imaging is expected to increase by approximately a factor 50 in the near future thanks to the planned improvements of the electron beam power and the detection efficiency of the neutron detector.
{"title":"Neutron performance and future prospect of the compact electron accelerator-driven neutron facility AISTANS","authors":"K. Kino, T. Fujiwara, M. Furusaka, T. Muroga, B. O’Rourke, N. Oshima, Y. Tomota","doi":"10.3233/jnr-220022","DOIUrl":"https://doi.org/10.3233/jnr-220022","url":null,"abstract":"The neutron wavelength resolution, Bragg-edge measurement ability and future prospects regarding the neutron count rate were investigated at AISTANS. The wavelength resolution evaluated by Bragg-edge analysis using an iron powder sample is in reasonably good agreement with calculations at neutron wavelengths of 0.2–0.3 nm. Bragg-edge imaging was also performed on a steel plate sample with distinct regions of BCC and FCC crystallinity, and the different crystal structures were successfully discriminated. In addition, an aluminum sample containing a friction stir spot welding region was also measured and the 200 and 111 Bragg-edges at the two joining areas were observed. However, it was hard to characterize the difference in texture between the two areas. The neutron counting rate for Bragg-edge imaging is expected to increase by approximately a factor 50 in the near future thanks to the planned improvements of the electron beam power and the detection efficiency of the neutron detector.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42616576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Baxter, T. Gutberlet, K. Kino, Y. Kiyanagi, Hiroaki Kumada, Y. Otake, Masato Takamura, Xuewu Wang
{"title":"Editorial Proc. UCANS IX Online Conference, March 28–31, 2022","authors":"D. Baxter, T. Gutberlet, K. Kino, Y. Kiyanagi, Hiroaki Kumada, Y. Otake, Masato Takamura, Xuewu Wang","doi":"10.3233/jnr-220048","DOIUrl":"https://doi.org/10.3233/jnr-220048","url":null,"abstract":"","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46908754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Bikchurina, Tymofey Bykov, E. Byambatseren, Ibrahem K. Ibrahem, D. Kasatov, I. Kolesnikov, V. Konovalova, A. Koshkarev, A. Makarov, G. Ostreinov, S. Savinov, E. Sokolova, I. Sorokin, I. Shchudlo, T. Sycheva, G. Verkhovod, S. Taskaev
A high flux neutron source based on a vacuum-insulated tandem accelerator (VITA) and a lithium target has been proposed and developed at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. We describe VITA which provides a dc proton/deuteron beam with an energy within a range of 0.6–2.3 MeV with a current from 1 nA to 10 mA. VITA is also capable of producing α-particles through the 7Li(p,α)α and 11B(p,α) α α reactions, 478 keV photons through the 7Li(p,p ′ γ)7Li reaction and positrons through the 19F(p,e+e−)16O reaction. We present several applications of this source: boron neutron capture therapy, nuclear cross sections determination, lithium target study, radiation blistering of metals during proton implantation and the radiation testing of promising materials.
{"title":"VITA high flux neutron source for various applications","authors":"M. Bikchurina, Tymofey Bykov, E. Byambatseren, Ibrahem K. Ibrahem, D. Kasatov, I. Kolesnikov, V. Konovalova, A. Koshkarev, A. Makarov, G. Ostreinov, S. Savinov, E. Sokolova, I. Sorokin, I. Shchudlo, T. Sycheva, G. Verkhovod, S. Taskaev","doi":"10.3233/jnr-220020","DOIUrl":"https://doi.org/10.3233/jnr-220020","url":null,"abstract":"A high flux neutron source based on a vacuum-insulated tandem accelerator (VITA) and a lithium target has been proposed and developed at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. We describe VITA which provides a dc proton/deuteron beam with an energy within a range of 0.6–2.3 MeV with a current from 1 nA to 10 mA. VITA is also capable of producing α-particles through the 7Li(p,α)α and 11B(p,α) α α reactions, 478 keV photons through the 7Li(p,p ′ γ)7Li reaction and positrons through the 19F(p,e+e−)16O reaction. We present several applications of this source: boron neutron capture therapy, nuclear cross sections determination, lithium target study, radiation blistering of metals during proton implantation and the radiation testing of promising materials.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47822528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Kunieda, Kazuyoshi Yamamoto, C. Konno, Y. Iwamoto, O. Iwamoto, Y. Wakabayashi, Yujiro Ikeda
Double-differential cross-sections of the 9Be(p,xn) reaction are newly evaluated based on the Wakabayashi’s function and neutronics analysis up to 12 MeV for a new nuclear data library, JENDL-5. We devoted our efforts especially to the re-optimization of the absolute cross-sections and the interpolation of the neutron energy spectra. Through the comparisons between the thick target yield measurements and Monte-Carlo simulations at different proton energies and neutron emission angles, we conclude that JENDL-5 gives the best evaluation in the world.
{"title":"Estimation of double-differential cross-sections of 9Be(p,xn) reaction for new nuclear data library JENDL-5","authors":"S. Kunieda, Kazuyoshi Yamamoto, C. Konno, Y. Iwamoto, O. Iwamoto, Y. Wakabayashi, Yujiro Ikeda","doi":"10.3233/jnr-220019","DOIUrl":"https://doi.org/10.3233/jnr-220019","url":null,"abstract":"Double-differential cross-sections of the 9Be(p,xn) reaction are newly evaluated based on the Wakabayashi’s function and neutronics analysis up to 12 MeV for a new nuclear data library, JENDL-5. We devoted our efforts especially to the re-optimization of the absolute cross-sections and the interpolation of the neutron energy spectra. Through the comparisons between the thick target yield measurements and Monte-Carlo simulations at different proton energies and neutron emission angles, we conclude that JENDL-5 gives the best evaluation in the world.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43864213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In many neutron scattering experiments, 3He-gas position-sensitive detectors (PSDs) are employed to obtain high-quality data. However, the exact position where a neutron is detected cannot be determined if two or more neutrons are simultaneously captured at different positions. This results in noise and degrades the quality of the data. In particular, such noise is a serious source of spurious scattering in inelastic neutron scattering instruments equipped with a large number of long PSDs recently developed at pulsed neutron sources. Herein, we introduce a pulse-width-discriminating PSD system that monitors the pulse width and height of the collected data. The system utilizes previously developed neutron-readout boards and removes instances of two or more simultaneous captures from the data to significantly improve the performance of PSDs. We also propose a new program to monitor the pulse width from PSD data using a hardware function implemented for other purposes. We confirm that the noise decreases to a level almost equal to that of the background. Although the developed program is applied to an inelastic scattering experiment, it is applicable to other types of experiments in which mispositioned signals should be eliminated as noise.
{"title":"Development of a pulse-width-discriminating 3He position-sensitive detector system","authors":"Setsuo Sato, R. Kajimoto, Y. Inamura","doi":"10.3233/jnr-220016","DOIUrl":"https://doi.org/10.3233/jnr-220016","url":null,"abstract":"In many neutron scattering experiments, 3He-gas position-sensitive detectors (PSDs) are employed to obtain high-quality data. However, the exact position where a neutron is detected cannot be determined if two or more neutrons are simultaneously captured at different positions. This results in noise and degrades the quality of the data. In particular, such noise is a serious source of spurious scattering in inelastic neutron scattering instruments equipped with a large number of long PSDs recently developed at pulsed neutron sources. Herein, we introduce a pulse-width-discriminating PSD system that monitors the pulse width and height of the collected data. The system utilizes previously developed neutron-readout boards and removes instances of two or more simultaneous captures from the data to significantly improve the performance of PSDs. We also propose a new program to monitor the pulse width from PSD data using a hardware function implemented for other purposes. We confirm that the noise decreases to a level almost equal to that of the background. Although the developed program is applied to an inelastic scattering experiment, it is applicable to other types of experiments in which mispositioned signals should be eliminated as noise.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44740659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Hu, Hiroki Tanaka, K. Akita, R. Kakino, T. Aihara, K. Nihei, K. Ono
The world’s first accelerator based epithermal neutron source for clinical boron neutron capture therapy (BNCT) was designed, developed, and commissioned between 2008 and 2010 by Sumitomo Heavy Industries in collaboration with Kyoto University at the Kyoto University Institute for Integrated Radiation and Nuclear Science. The accelerator system is cyclotron-based and accelerates a proton up to an energy of approximately 30 MeV. The proton strikes a beryllium target, which produces fast neutrons that traverse a beam shaping assembly composed of a combination of lead, iron, aluminum, and calcium fluoride to reduce the neutron energy down to the epithermal range (∼10 keV) suitable for BNCT. The system is designed to produce an epithermal neutron flux of up to 1.4 × 10 9 n · cm − 2 · s − 1 (exiting from the moderator of a 12 cm diameter collimator) with a proton current of 1 mA. In 2017, the same type of accelerator was installed at the Kansai BNCT Medical Center and in March 2020 the system received medical device approval in Japan (Sumitomo Heavy Industries, NeuCure® BNCT system). Soon after, BNCT for unresectable, locally advanced, and recurrent carcinoma of the head and neck region was approved by the Japanese government for reimbursement covered by the national health insurance system.
{"title":"Accelerator based epithermal neutron source for clinical boron neutron capture therapy","authors":"N. Hu, Hiroki Tanaka, K. Akita, R. Kakino, T. Aihara, K. Nihei, K. Ono","doi":"10.3233/jnr-220037","DOIUrl":"https://doi.org/10.3233/jnr-220037","url":null,"abstract":"The world’s first accelerator based epithermal neutron source for clinical boron neutron capture therapy (BNCT) was designed, developed, and commissioned between 2008 and 2010 by Sumitomo Heavy Industries in collaboration with Kyoto University at the Kyoto University Institute for Integrated Radiation and Nuclear Science. The accelerator system is cyclotron-based and accelerates a proton up to an energy of approximately 30 MeV. The proton strikes a beryllium target, which produces fast neutrons that traverse a beam shaping assembly composed of a combination of lead, iron, aluminum, and calcium fluoride to reduce the neutron energy down to the epithermal range (∼10 keV) suitable for BNCT. The system is designed to produce an epithermal neutron flux of up to 1.4 × 10 9 n · cm − 2 · s − 1 (exiting from the moderator of a 12 cm diameter collimator) with a proton current of 1 mA. In 2017, the same type of accelerator was installed at the Kansai BNCT Medical Center and in March 2020 the system received medical device approval in Japan (Sumitomo Heavy Industries, NeuCure® BNCT system). Soon after, BNCT for unresectable, locally advanced, and recurrent carcinoma of the head and neck region was approved by the Japanese government for reimbursement covered by the national health insurance system.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46142117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Quintieri, S. Lilley, D. Wilcox, D. Findlay, D. Jenkins, S. Gallimore, D. Haynes
Spallation targets for neutron production with high energy protons are made of high density and high atomic number materials in order to maximise the yield of neutrons for all the instruments around. Operating a proton beam onto a spallation target produces residual radioactive nuclei either as direct product of the spallation process and as secondary low energy neutron absorption. A reliable estimation of the overall activation and decay heat, as a function of the cooling time and irradiation profile history, is fundamental for a valuable design of the radiation shielding and cooling system during the operation phase as well for envisaging the optimal storage solution at the end of life of the target. This work presents the comparison between the FLUKA predictions of the decay heat in the ISIS TS1 target operated between 2014 and 2019 and the decay heat estimations derived from the measurement of the temperature in each plate at different cooling times. The agreement between the FLUKA predictions and the experimentally assessed values shows and quantifies the goodness of the FLUKA model in predicting measurable physical quantities relevant for the engineering thermal design of the target/reflector and moderator (TRAM) assembly. In addition, it also provides an indirect evidence of the accuracy of the simulated spallation physics and neutron transport throughout the TRAM assembly. Finally this work attempts to highlight and propose a general empirical procedure that could be eventually applied and used to proficiently measure the decay heat at whatever cooling time in targets with similar ISIS design.
{"title":"Decay heat in ISIS spallation target: simulations and measurements","authors":"L. Quintieri, S. Lilley, D. Wilcox, D. Findlay, D. Jenkins, S. Gallimore, D. Haynes","doi":"10.3233/jnr-220030","DOIUrl":"https://doi.org/10.3233/jnr-220030","url":null,"abstract":"Spallation targets for neutron production with high energy protons are made of high density and high atomic number materials in order to maximise the yield of neutrons for all the instruments around. Operating a proton beam onto a spallation target produces residual radioactive nuclei either as direct product of the spallation process and as secondary low energy neutron absorption. A reliable estimation of the overall activation and decay heat, as a function of the cooling time and irradiation profile history, is fundamental for a valuable design of the radiation shielding and cooling system during the operation phase as well for envisaging the optimal storage solution at the end of life of the target. This work presents the comparison between the FLUKA predictions of the decay heat in the ISIS TS1 target operated between 2014 and 2019 and the decay heat estimations derived from the measurement of the temperature in each plate at different cooling times. The agreement between the FLUKA predictions and the experimentally assessed values shows and quantifies the goodness of the FLUKA model in predicting measurable physical quantities relevant for the engineering thermal design of the target/reflector and moderator (TRAM) assembly. In addition, it also provides an indirect evidence of the accuracy of the simulated spallation physics and neutron transport throughout the TRAM assembly. Finally this work attempts to highlight and propose a general empirical procedure that could be eventually applied and used to proficiently measure the decay heat at whatever cooling time in targets with similar ISIS design.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46299168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Zanini, E. Dian, D. Dijulio, B. Folsom, E. Klinkby, Z. Kókai, J. I. Marquez Damian, B. Rataj, N. Rizzi, V. Santoro, M. Strothmann, A. Takibayev, R. Wagner, O. Zimmer
The goal of the “Workshop on Very Cold and Ultra Cold Neutron Sources for ESS” was to discuss scientific cases, ideas and possibilities for the implementation of sources of Very Cold and Ultra Cold neutrons at the European Spallation Source. The ESS facility, presently under construction, offers several possibilities for in-pile UCN or VCN sources, in primis thanks to the available space below the spallation target where additional neutron sources can be placed to complement those above the target. Neutron beams can be extracted over a wide angular range with a grid of forty-two beamports with 6° average angular separation, allowing future instruments to be installed which may view either the upper or lower moderator systems. Of greatest interest for fundamental physics is the so-called Large Beamport foreseen for the NNBAR experiment. This beamport is also particularly well suited to feed a UCN source, for which several ideas were presented that employ either superfluid helium or solid deuterium as established neutron converter materials. Concepts for VCN sources make use of novel materials for VCN production and/or advanced reflectors to increase yields in the coldest part of the neutron spectrum from a cryogenic neutron source. In this paper we discuss these ideas and the possible locations of UCN and VCN sources at ESS.
{"title":"Very cold and ultra cold neutron sources for ESS","authors":"L. Zanini, E. Dian, D. Dijulio, B. Folsom, E. Klinkby, Z. Kókai, J. I. Marquez Damian, B. Rataj, N. Rizzi, V. Santoro, M. Strothmann, A. Takibayev, R. Wagner, O. Zimmer","doi":"10.3233/jnr-220040","DOIUrl":"https://doi.org/10.3233/jnr-220040","url":null,"abstract":"The goal of the “Workshop on Very Cold and Ultra Cold Neutron Sources for ESS” was to discuss scientific cases, ideas and possibilities for the implementation of sources of Very Cold and Ultra Cold neutrons at the European Spallation Source. The ESS facility, presently under construction, offers several possibilities for in-pile UCN or VCN sources, in primis thanks to the available space below the spallation target where additional neutron sources can be placed to complement those above the target. Neutron beams can be extracted over a wide angular range with a grid of forty-two beamports with 6° average angular separation, allowing future instruments to be installed which may view either the upper or lower moderator systems. Of greatest interest for fundamental physics is the so-called Large Beamport foreseen for the NNBAR experiment. This beamport is also particularly well suited to feed a UCN source, for which several ideas were presented that employ either superfluid helium or solid deuterium as established neutron converter materials. Concepts for VCN sources make use of novel materials for VCN production and/or advanced reflectors to increase yields in the coldest part of the neutron spectrum from a cryogenic neutron source. In this paper we discuss these ideas and the possible locations of UCN and VCN sources at ESS.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46736503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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