Research

16 pages, 11611 KiB

Open AccessArticle

New Ballistic Neutron Guide for the Time-of-Flight Spectrometer FOCUS at PSI

by Fanni Juranyi, Masako Yamada, Christine Klauser, Lothar Holitzner and Uwe Filges

Quantum Beam Sci. 2024, 8(1), 8; https://doi.org/10.3390/qubs8010008 - 13 Feb 2024

Viewed by 920

FOCUS is a direct-geometry cold neutron time-of-flight spectrometer at SINQ (PSI, CH). Its neutron guide was exchanged in 2019/2020 within the SINQ Upgrade project, while the rest of the instrument remained unchanged. The new guide provided a significant intensity increase across the whole [...] Read more.

FOCUS is a direct-geometry cold neutron time-of-flight spectrometer at SINQ (PSI, CH). Its neutron guide was exchanged in 2019/2020 within the SINQ Upgrade project, while the rest of the instrument remained unchanged. The new guide provided a significant intensity increase across the whole spectrum, especially at short wavelengths, due to the more efficient transport and extended phase space of the transported neutrons. The practically available energy transfer range (at the neutron energy loss side) was increased to about 40 meV. The main reason for the intensity benefit at short incident wavelengths was the improved guide coating, whereas at long wavelengths it was the new ballistic shape. The interesting part of the guide is the “peanut shape” of the curved part in the horizontal plane. For this, we derived the analytical restriction on the geometry to avoid a direct line of sight from the source. The guide geometry and the supermirror coating were optimized using Mcoptimize, a particle swarm optimization routine employing Mcstas. Future ballistic neutron guides may profit from the presented approaches, optimization strategy, and results. Full article

(This article belongs to the Special Issue New Trends in Neutron Instrumentation, 2nd Edition)

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21 pages, 8316 KiB

Open AccessFeature PaperArticle

Microscopic Depictions of Vanishing Shampoo Foam Examined by Time-of-Flight Small-Angle Neutron Scattering

by Satoshi Koizumi, Yohei Noda, Takumi Inada, Tomoki Maeda, Shiho Yada, Tomokazu Yoshimura, Hiroshi Shimosegawa, Hiroya Fujita, Munehiro Yamada and Yukako Matsue

Quantum Beam Sci. 2023, 7(1), 4; https://doi.org/10.3390/qubs7010004 - 29 Jan 2023

Cited by 1 | Viewed by 1672

Abstract

A novel surfactant of N–dodecanoyl–N–(2-hydroxyethyl)–β–alanine (coded as C₁₂–EtOH–βAla) was synthesized by modifying the methyl group of N–dodecanoyl–N–methyl–β–alanine (coded as C₁₂–Me–βAla). Amino-acid-type surfactants (C₁₂–EtOH– [...] Read more.

A novel surfactant of N–dodecanoyl–N–(2-hydroxyethyl)–β–alanine (coded as C₁₂–EtOH–βAla) was synthesized by modifying the methyl group of N–dodecanoyl–N–methyl–β–alanine (coded as C₁₂–Me–βAla). Amino-acid-type surfactants (C₁₂–EtOH–βAla and C₁₂–Me–βAla) are more healthy and environmentally friendly compared to sodium dodecyl sulfate (SDS). To investigate the microstructures of these new surfactants, we employed a method of time-of-flight small-angle neutron scattering (TOF SANS) at a pulsed neutron source, Tokai Japan (J–PARC). The advances in TOF SANS enable simultaneous multiscale observations without changing the detector positions, which is usually necessary for SANS at the reactor or small-angle X-ray scattering. We performed in situ and real-time observations of microstructures of collapsing shampoo foam covering over a wide range of length scales from 100 to 0.1 nm. After starting an air pump, we obtained time-resolved SANS from smaller wave number, small-angle scattering attributed to (1) a single bimolecular layer with a disk shape, (2) micelles in a bimolecular layer, and (3) incoherent scattering due to the hydrogen atoms of surfactants. The micelle in the foam film was the same size as the micelle found in the solution before foaming. The film thickness (~27 nm) was stable for a long time (<3600 s), and we simultaneously found a Newton black film of 6 nm thickness at a long time limit (~1000 s). The incoherent scattering obtained with different contrasts using protonated and deuterated water was crucial to determining the water content in the foam film, which was about 10~5 wt%. Full article

(This article belongs to the Special Issue New Trends in Neutron Instrumentation, 2nd Edition)

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11 pages, 15590 KiB

Open AccessArticle

Transmission Bender as an Analyzer Device for MIEZE

by Johanna K. Jochum, Jos F. K. Cooper, Lukas M. Vogl, Peter Link, Olaf Soltwedel, Peter Böni, Christian Pfleiderer and Christian Franz

Quantum Beam Sci. 2022, 6(3), 26; https://doi.org/10.3390/qubs6030026 - 02 Aug 2022

Cited by 2 | Viewed by 2159

Abstract

MIEZE (Modulation of IntEnsity with Zero Effort) spectroscopy is a high-resolution spin echo technique optimized for the study of magnetic samples and samples under depolarizing conditions. It requires a polarization analyzer in between spin flippers and the sample position. For this, the device [...] Read more.

MIEZE (Modulation of IntEnsity with Zero Effort) spectroscopy is a high-resolution spin echo technique optimized for the study of magnetic samples and samples under depolarizing conditions. It requires a polarization analyzer in between spin flippers and the sample position. For this, the device needs to be compact and insensitive to stray fields from large magnetic fields at the sample position. For MIEZE, in small angle scattering geometry, it is further essential that the analyzer does not affect the beam profile, divergence, or trajectory. Here, we compare different polarization analyzers for MIEZE and show the performance of the final design, a transmission bender, which we compare to McStas simulations. Commissioning experiments have uncovered spurious scattering in the scattering profile of the bender, which most likely originates from double Bragg scattering in bent silicon. Full article

(This article belongs to the Special Issue New Trends in Neutron Instrumentation, 2nd Edition)

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15 pages, 3928 KiB

Open AccessArticle

Further Optimized Design of a Nested Rotate Sextupole Permanent Magnet Lens for the Focusing of Pulsed Neutrons

by Taisen Zuo, Zhanjiang Lu, Changdong Deng, Songwen Xiao, Yongcheng He, Zhenqiang He, Xiong Lin, Changli Ma, Zehua Han and He Cheng

Quantum Beam Sci. 2022, 6(3), 25; https://doi.org/10.3390/qubs6030025 - 26 Jul 2022

Cited by 2 | Viewed by 1658

Abstract

A compact nested rotate sextupole permanent magnet (Nest-Rot-SPM) lens was designed for the focusing of pulsed neutrons. It is based on the working conditions of the Very Small Angle Neutron Scattering (VSANS) instrument at the China Spallation Neutron Source (CSNS), and is expected [...] Read more.

A compact nested rotate sextupole permanent magnet (Nest-Rot-SPM) lens was designed for the focusing of pulsed neutrons. It is based on the working conditions of the Very Small Angle Neutron Scattering (VSANS) instrument at the China Spallation Neutron Source (CSNS), and is expected to focus a neutron pulse from 6 Å to 10.5 Å, without chromatic aberration. Three hurdles must be addressed, i.e., the tremendous torque, the heat deposition, and the synchronization with the neutron pulse, respectively. The bore diameter and segment length of the lens are optimized using a formula analysis of the key parameters and model simulations of the torque and heat deposition. A twin torque canceling design is used to reduce the torque to one-third of its original value, or even lower. The goal of this project is to take the device into practical use in the VSANS at the CSNS. Full article

(This article belongs to the Special Issue New Trends in Neutron Instrumentation, 2nd Edition)

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8 pages, 1516 KiB

Open AccessArticle

Demonstration of Neutron Phase Imaging Based on Talbot–Lau Interferometer at Compact Neutron Source RANS

by Hidekazu Takano, Yanlin Wu, Tetsuo Samoto, Atsushi Taketani, Takaoki Takanashi, Chihiro Iwamoto, Yoshie Otake and Atsushi Momose

Quantum Beam Sci. 2022, 6(2), 22; https://doi.org/10.3390/qubs6020022 - 01 Jun 2022

Viewed by 1935

Abstract

Neutron imaging based on a compact Talbot–Lau interferometer was demonstrated using the RIKEN accelerator-driven compact neutron source (RANS). A compact Talbot–Lau interferometer consisting of gadolinium absorption gratings and a silicon phase grating was constructed and connected to the RANS. Because of pulsed thermal [...] Read more.

Neutron imaging based on a compact Talbot–Lau interferometer was demonstrated using the RIKEN accelerator-driven compact neutron source (RANS). A compact Talbot–Lau interferometer consisting of gadolinium absorption gratings and a silicon phase grating was constructed and connected to the RANS. Because of pulsed thermal neutrons from the RANS and a position-sensitive detector equipped with time-of-flight (TOF) analysis, moiré interference patterns generated using the interferometer were extracted at a TOF range around the design wavelength (2.37 Å) optimal for the interferometer. Differential phase and scattering images of the metal rod samples were obtained through phase-stepping measurements with the interferometer. This demonstrates the feasibility of neutron phase imaging using a compact neutron facility and the potential for flexible and unique applications for nondestructive evaluation. Full article

(This article belongs to the Special Issue New Trends in Neutron Instrumentation, 2nd Edition)

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7 pages, 373 KiB

Open AccessArticle

Response to Mono-Energetic Neutrons and Light Output Function for Liquid Organic Scintillators PYR5/DIPN and THIO5/DIPN

by Jaroslav Jánský, Jiří Janda, Michal Košťál, Zdeněk Matěj, Tomáš Bílý, Věra Mazánková, Filip Mravec and František Cvachovec

Quantum Beam Sci. 2022, 6(2), 18; https://doi.org/10.3390/qubs6020018 - 12 May 2022

Cited by 1 | Viewed by 2369

Abstract

Liquid organic scintillators are important devices for measurements of neutron radiation. Currently, large-scale liquid organic scintillators have capabilities of detecting neutrons, but the determination of the neutron energy spectra is a challenge. This work aims to measure the responses of two liquid two-component [...] Read more.

Liquid organic scintillators are important devices for measurements of neutron radiation. Currently, large-scale liquid organic scintillators have capabilities of detecting neutrons, but the determination of the neutron energy spectra is a challenge. This work aims to measure the responses of two liquid two-component scintillators to mono-energetic neutron radiation and to determine their light output function, which is necessary for proper neutron energy spectra determination. Both scintillators are composed of the solvent di-iso-propyl-naphthalene (DIPN) mixed isomers. The first scintillator, labeled PYR5/DIPN, contains the luminophore 1-phenyl-3-(2,4,6-trimethyl-phenyl)-2-pyrazoline with a concentration of 5 g/L. The second scintillator labeled THIO5/DIPN contains the luminophore 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene also with a concentration of 5 g/L. The responses to neutron energies of 1.5 MeV, 2.5 MeV, and 19 MeV are measured at PTB in Braunschweig. The responses to neutron energies of 2.45 MeV and 14 MeV were measured at CTU in Prague using DD and DT reactions. The responses to a silicon filtered beam were measured at Research Centre Řež. The measurements were processed using a two-parameter spectrometric system NGA-01 to discriminate neutrons from gamma rays. The obtained responses are dominated by recoil protons from elastic collisions of neutrons with hydrogen atoms. The edge of the response of recoil protons gives information about the light output of neutrons, compared to gamma rays for the same radiation energy. The light output function for protons in the PYR5/DIPN scintillator is

L (E_{p}) = 0.6294 E_{p} - 1.00 (1 - \exp (- 0.4933 E_{p}^{0.95}))

. The light output function for protons in the THIO5/DIPN scintillator is

L (E_{p}) = 0.6323 E_{p} - 1.00 (1 - \exp (- 0.4986 E_{p}^{0.9883}))

. The light output functions well resemble the standard shape, and they are quite similar to each other. That suggests a weak influence of the luminophore on the light output function. The light output functions are ready to be incorporated to the response matrix for the neutron energy spectra determination. Full article

(This article belongs to the Special Issue New Trends in Neutron Instrumentation, 2nd Edition)

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13 pages, 4842 KiB

Open AccessArticle

Fast Neutron Scintillator Screens for Neutron Imaging Using a Layered Polymer-Phosphor Architecture

by William Chuirazzi, Aaron Craft, Burkhard Schillinger, Jesus Mendoza, Steven Cool and Adrian Losko

Quantum Beam Sci. 2022, 6(2), 14; https://doi.org/10.3390/qubs6020014 - 01 Apr 2022

Cited by 4 | Viewed by 3021

Abstract

Fast neutrons enable a nondestructive examination of dense, large, and highly attenuating samples due to their lower interaction probability compared to thermal neutrons. However, this also creates a challenge in fast neutron imaging, as the thicker sensors necessary to detect fast neutrons degrade [...] Read more.

Fast neutrons enable a nondestructive examination of dense, large, and highly attenuating samples due to their lower interaction probability compared to thermal neutrons. However, this also creates a challenge in fast neutron imaging, as the thicker sensors necessary to detect fast neutrons degrade an image’s spatial resolution due to scattering within the sensor and the indeterminate depth of interaction in the sensor. This work explores the advantages of a fast neutron imaging screen with a layered polymer-phosphor screen approach as opposed to a mixed polymer-phosphor screen typically used in fast neutron imaging. Proton recoil is the primary conversion mechanism for fast neutron imaging. Simulations showed that the recoil proton range of typical fast neutrons is approximately 200 µm, however, tests at Idaho National Laboratory revealed that the light output of these screens increased at much greater polymer thicknesses. The NECTAR fast neutron beamline at FRM II was used to test the imaging performance of layered fast neutron imaging screens. Distinguishing between the fast-neutron and γ-ray signals is a major challenge in fast neutron imaging because all fast neutron sources also produce γ-rays. A relative comparison between a control plate and the fast neutron screen was made to distinguish between a γ-ray and fast neutron signals. MCNP modeling quantified the γ-ray and fast neutron contributions to the images measured at NECTAR, which were approximately a 75% γ-ray image. Full article

(This article belongs to the Special Issue New Trends in Neutron Instrumentation, 2nd Edition)

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17 pages, 4805 KiB

Open AccessArticle

Optimization of the Guide Design of MIRACLES, the Neutron Time-of-Flight Backscattering Spectrometer at the European Spallation Source

by Félix J. Villacorta, Damián Martín Rodríguez, Mads Bertelsen and Heloisa N. Bordallo

Quantum Beam Sci. 2022, 6(1), 3; https://doi.org/10.3390/qubs6010003 - 31 Dec 2021

Cited by 3 | Viewed by 2857

Abstract

To boost the science case of MIRACLES, the time-of-flight backscattering spectrometer at the European Spallation Source (ESS), an optimized neutron guide system, is proposed. This systematic study resulted in an enhancement in the transport of cold neutrons, compared with the previous conceptual design, [...] Read more.

To boost the science case of MIRACLES, the time-of-flight backscattering spectrometer at the European Spallation Source (ESS), an optimized neutron guide system, is proposed. This systematic study resulted in an enhancement in the transport of cold neutrons, compared with the previous conceptual design, with wavelengths ranging from λ = 2 Å to 20 Å along the 162.5-m distance from source to sample. This maintained the undisturbed main focus of the instrument, viz, to carry out quasielastic and inelastic neutron scattering (QENS and INS) experiments on a large dynamic range and for both energy-gain and energy-loss sides. To improve the collection of cold neutrons from the source and direct them to the sample position, the vertical geometry was adjusted to an adapted version of a ballistic elliptical profile. Its horizontal geometry was conceived to: (i) keep the high-resolution performance of the instrument, and (ii) minimize the background originating from fast and thermal neutrons. To comply with the first requirement, a narrow guide section at the pulse shaping chopper position has been implemented. To fulfil the second, a curved guide segment has been chosen to suppress neutrons with wavelengths λ < 2 Å. Subsequent tailoring of the phase space provided an efficient transport of cold neutrons along the beamline to reach a 3 × 3 cm² sample. Finally, additional calculations were performed to present a potential upgrade, with the exchange of the final segment, to focus on samples of approximately 1 × 1 cm²; the proposal anticipates a flux increase of 70% in this 1 cm² sample area. Full article

(This article belongs to the Special Issue New Trends in Neutron Instrumentation, 2nd Edition)

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