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A New High-Intensity Source for Ultracold Neutrons
Authors:
K. Abe,
S. Ahmed,
B. Algohi,
D. Anthony,
L. Barron-Palos,
Y. Bylinsky,
M. Bosse,
M. P. Bradley,
A. Brossard,
J. Chak,
R. Chiba,
C. Davis,
R. de Vries,
K. Dong,
K. Drury,
B. Franke,
D. Fujimoto,
R. Fujitani,
M. Gericke,
P. Giampa,
C. Gibson,
R. Golub,
K. Hatanaka,
T. Hepworth,
T. Higuchi
, et al. (56 additional authors not shown)
Abstract:
The TRIUMF UltraCold Advanced Neutron (TUCAN) collaboration has completed a new superthermal source for ultracold neutrons (UCNs) at TRIUMF. It uses neutrons from a spallation target driven by TRIUMF's %520-MeV main cyclotron. Heavy water and liquid deuterium serve as neutron moderators, and inelastic scattering inside superfluid $^4$He at around \qty{1.1}{\kelvin} slows the neutrons down to becom…
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The TRIUMF UltraCold Advanced Neutron (TUCAN) collaboration has completed a new superthermal source for ultracold neutrons (UCNs) at TRIUMF. It uses neutrons from a spallation target driven by TRIUMF's %520-MeV main cyclotron. Heavy water and liquid deuterium serve as neutron moderators, and inelastic scattering inside superfluid $^4$He at around \qty{1.1}{\kelvin} slows the neutrons down to become ultracold. During commissioning runs with the completed source, including the deuterium moderator, up to $1.47(2)\times 10^7$ UCNs were detected in the experimental area after irradiating the target and accumulating UCNs in the source for \qty{60}{\second}. Up to \qty{6.75(3)e5} UCN/s were detected during continuous operation, more than at any other source in the world.
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Submitted 17 August, 2026; v1 submitted 3 July, 2026;
originally announced July 2026.
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Initial Performance of the TUCAN Magnetically Shielded Room
Authors:
S. Ahmed,
B. Algohi,
D. Anthony,
P. Berard,
L. Barron-Palos,
M. Bosse,
A. Brossard,
J. Chak,
R. Curtis,
C. Davis,
R. de Vries,
K. Dong,
B. Dowie,
K. Drury,
P. Fierlinger,
B. Franke,
D. Fujimoto,
R. Fujitani,
P. Giampa,
C. Gibson,
R. Golub,
K. Hatanaka,
T. Hepworth,
T. Higuchi,
J. Hussain
, et al. (42 additional authors not shown)
Abstract:
The TRIUMF Ultracold Advanced Neutron (TUCAN) collaboration has commissioned a large magnetically shielded room to be used for measuring the neutron electric dipole moment (nEDM) to a precision of $10^{-27}~e\mathrm{cm}$. The room is composed of five layers of MuMetal and one layer of copper and sits within the $\lesssim 370~μ\mathrm{T}$ ambient field produced by the TRIUMF cyclotron. Within this…
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The TRIUMF Ultracold Advanced Neutron (TUCAN) collaboration has commissioned a large magnetically shielded room to be used for measuring the neutron electric dipole moment (nEDM) to a precision of $10^{-27}~e\mathrm{cm}$. The room is composed of five layers of MuMetal and one layer of copper and sits within the $\lesssim 370~μ\mathrm{T}$ ambient field produced by the TRIUMF cyclotron. Within this environment, the quasi-static shielding factor was measured to be $3.25(2) \times 10^4$ at $0.01~\mathrm{Hz}$ with an external peak-to-peak perturbation of $2~μ\mathrm{T}$. Without the large ambient cyclotron field, the shielding factor improves to $3.75(4)\times 10^4$ at the same perturbation amplitude and frequency. After idealization in the cyclotron field, the residual field at the room center was $B = 1.8(2)~\mathrm{nT}$ and the vertical first-order gradient across the central 1~m$^3$ ($dB_{\mathrm{z}}/dz$) was $-279(64)~\mathrm{pT/m}$. With additional improvement to the idealization, and with active compensation, we expect the room to be adequate for a $10^{-27}~e\mathrm{cm}$ nEDM search.
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Submitted 16 April, 2026;
originally announced April 2026.
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Ultracold Neutron Guide-Coating Facility at U.Winnipeg
Authors:
T. Hepworth,
A. Zahra,
B. Algohi,
R. de Vries,
S. Pankratz,
P. Switzer,
T. Reimer,
M. McCrea,
J. W. Martin,
R. Mammei,
D. Anthony,
L. Barrón-Palos,
M. Bossé,
M. P. Bradley,
A. Brossard,
T. Bui,
J. Chak,
R. Chiba,
C. Davis,
K. Drury,
D. Fujimoto,
R. Fujitani,
M. Gericke,
P. Giampa,
C. Gibson
, et al. (50 additional authors not shown)
Abstract:
We report the construction and commissioning of a new ultracold neutron (UCN) guide-coating facility at the University of Winnipeg. The facility employs pulsed laser deposition (PLD) to produce diamond-like carbon (DLC) coatings on cylindrical UCN guides up to 1 m in length with a 200 mm outer diameter. DLC is a promising material for UCN transport and storage due to its high real component of the…
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We report the construction and commissioning of a new ultracold neutron (UCN) guide-coating facility at the University of Winnipeg. The facility employs pulsed laser deposition (PLD) to produce diamond-like carbon (DLC) coatings on cylindrical UCN guides up to 1 m in length with a 200 mm outer diameter. DLC is a promising material for UCN transport and storage due to its high real component of the optical potential, low neutron absorption cross section, and low depolarization probabilities. First coating attempts on a full length aluminum UCN guide and matching blank flange were successfully coated with a carbon film with density of 2.3 g/cm$^3$, corresponding to optical potentials of 200 neV, as measured by X-ray reflectometry (XRR). Coating thicknesses were measured to be 90 nm for the UCN guide and 180 nm for the flange with no evidence of delamination. The implementation of a plasma plume collimator and plasma feed back control via a time of flight in vacuum ion probe produced a film with an XRR measured density of 2.8 g/cm$^3$, corresponding to an optical potential of 240 neV. This 80 nm thick film had poor adhesion to the aluminum tube substrate. These results establish a baseline for the coating facility. Ongoing and future work focuses on improving the diamond content of films and adhesion through plasma plume collimation, TOF ion probe feed back, and pre/post treatment methods with the goal of providing high quality DLC UCN guides for the TUCAN experiment at TRIUMF.
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Submitted 4 May, 2026; v1 submitted 7 October, 2025;
originally announced October 2025.
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Initial results of the TRIUMF ultracold advanced neutron source
Authors:
B. Algohi,
D. Anthony,
L. Barrón-Palos,
M. Bossé,
M. P. Bradley,
A. Brossard,
T. Bui,
J. Chak,
R. Chiba,
C. Davis,
R. de Vries,
K. Drury,
B. Franke,
D. Fujimoto,
R. Fujitani,
M. Gericke,
D. Georgescu,
P. Giampa,
C. Gibson,
R. Golub,
K. Hatanaka,
T. Hepworth,
T. Higuchi,
G. Ichikawa,
I. Ide
, et al. (61 additional authors not shown)
Abstract:
We report the first results on ultracold neutron production from a new spallation-driven superfluid $^4$He (He-II) source at TRIUMF, which is being prepared for a new, precise measurement of the neutron electric dipole moment. A total of $(9.3 \pm 0.8)\times 10^{5}$ ultracold neutrons were observed at a proton beam current of \SI{37}{\uA}, when the target was irradiated for a period of \SI{60}{\s}…
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We report the first results on ultracold neutron production from a new spallation-driven superfluid $^4$He (He-II) source at TRIUMF, which is being prepared for a new, precise measurement of the neutron electric dipole moment. A total of $(9.3 \pm 0.8)\times 10^{5}$ ultracold neutrons were observed at a proton beam current of \SI{37}{\uA}, when the target was irradiated for a period of \SI{60}{\s}. The results are in fair agreement with expectations based on a detailed simulation of neutron transport and ultracold neutron source cryogenics. There is some indication that the new source might not be as limited by the conduction of heat through the He-II as originally expected. The results indicate that the source is likely to make its ultimate production goals, once the liquid deuterium cold moderator system is completed, with the expectation that $5.7\times 10^7$~UCNs would be detected in the same experiment with full liquid levels. This would, for example, correspond to delivery of $1.4\times 10^6$~UCNs delivered to each of two nEDM measurement cells, and a statistical uncertainty of $1\times 10^{-27}~e$cm on the neutron EDM in 280 days of running.
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Submitted 7 June, 2026; v1 submitted 2 September, 2025;
originally announced September 2025.
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Neutron EDM Experiment with an Advanced Ultracold Neutron Source at TRIUMF
Authors:
T. Higuchi,
B. Algohi,
D. Anthony,
L. Barrón-Palos,
M. Bradley,
A. Brossard,
T. Bui,
J. Chak,
R. Chiba,
C. Davis,
R. de Vries,
K. Drury,
D. Fujimoto,
R. Fujitani,
M. Gericke,
P. Giampa,
R. Golub,
T. Hepworth,
G. Ichikawa,
S. Imajo,
A. Jaison,
B. Jamieson,
M. Katotoka,
S. Kawasaki,
M. Kitaguchi
, et al. (45 additional authors not shown)
Abstract:
The TRIUMF Ultracold Advanced Neutron (TUCAN) collaboration has been developing a high-intensity ultracold neutron (UCN) source aimed at searching for the neutron electric dipole moment (EDM) with a sensitivity goal of $10^{-27}\ e{\rm cm}$. This article reports on recent progress in commissioning of the UCN source and in the development of the neutron EDM spectrometer. In its final configuration,…
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The TRIUMF Ultracold Advanced Neutron (TUCAN) collaboration has been developing a high-intensity ultracold neutron (UCN) source aimed at searching for the neutron electric dipole moment (EDM) with a sensitivity goal of $10^{-27}\ e{\rm cm}$. This article reports on recent progress in commissioning of the UCN source and in the development of the neutron EDM spectrometer. In its final configuration, the accelerator-driven super-thermal UCN source will enable a neutron EDM experiment with two orders of magnitude improved statistics compared to the current best experiment. Substantial progress in 2024 allowed the collaboration to operate the complete source system, with the exception of the liquid deuterium cold moderator, resulting in the first production of UCNs. The status of the EDM spectrometer is also presented, with emphasis on UCN handling components and magnetic subsystems relevant to field control, shielding, and magnetometry.
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Submitted 18 July, 2026; v1 submitted 4 July, 2025;
originally announced July 2025.
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Cryogenic systems for the TUCAN EDM experiment
Authors:
Jeffery W. Martin,
B. Algohi,
D. Anthony,
L. Barrón-Palos,
M. Bradley,
A. Brossard,
T. Bui,
J. Chak,
C. Davis,
R. de Vries,
K. Drury,
D. Fujimoto,
R. Fujitani,
M. Gericke,
P. Giampa,
R. Golub,
T. Hepworth,
T. Higuchi,
G. Ichikawa,
S. Imajo,
A. Jaison,
B. Jamieson,
M. Katotoka,
S. Kawasaki,
M. Kitaguchi
, et al. (38 additional authors not shown)
Abstract:
The TUCAN (TRIUMF UltraCold Advanced Neutron) Collaboration is completing a new ultracold neutron (UCN) source. The UCN source will deliver UCNs to a neutron electric dipole moment (EDM) experiment. The EDM experiment is projected to be capable of an uncertainty of $1\times 10^{-27}~e$cm, competitive with other planned projects, and a factor of ten more precise than the present world's best. The T…
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The TUCAN (TRIUMF UltraCold Advanced Neutron) Collaboration is completing a new ultracold neutron (UCN) source. The UCN source will deliver UCNs to a neutron electric dipole moment (EDM) experiment. The EDM experiment is projected to be capable of an uncertainty of $1\times 10^{-27}~e$cm, competitive with other planned projects, and a factor of ten more precise than the present world's best. The TUCAN source is based on a UCN production volume of superfluid helium (He-II), held at 1~K, and coupled to a proton-driven spallation target. The production rate in the source is expected to be in excess of $10^7$~UCN/s; since UCN losses can be small in superfluid helium, this should allow us to build up a large number of UCNs. The spallation-driven superfluid helium technology is the principal aspect making the TUCAN project unique. The superfluid production volume was recently cooled, for the first time, and successfully filled with superfluid helium. The design principles of the UCN source are described, along with some of the challenging cryogenic milestones that were recently passed.
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Submitted 20 June, 2025; v1 submitted 6 June, 2025;
originally announced June 2025.
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A Flexible Data Acquisition System Architecture for the Nab Experiment
Authors:
D. G. Mathews,
H. Acharya,
C. B. Crawford,
M. H. Gervais,
A. P. Jezghani,
M. McCrea,
A. Nelsen,
A. Atencio,
N. Birge,
L. J. Broussard,
J. H. Choi,
F. M. Gonzalez,
H. Li,
N. Macsai,
A. Mendelsohn,
R. R. Mammei,
G. V. Riley,
R. A. Whitehead
Abstract:
The Nab experiment will measure the electron-neutrino correlation and Fierz interference term in free neutron beta decay to test the Standard Model and probe Beyond the Standard Model Physics. Using National Instrument's PXIe-5171 Reconfigurable Oscilloscope module, we have developed a data acquisition system that is not only capable of meeting Nab's specifications, but flexible enough to be adapt…
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The Nab experiment will measure the electron-neutrino correlation and Fierz interference term in free neutron beta decay to test the Standard Model and probe Beyond the Standard Model Physics. Using National Instrument's PXIe-5171 Reconfigurable Oscilloscope module, we have developed a data acquisition system that is not only capable of meeting Nab's specifications, but flexible enough to be adapted in situ as the experimental environment dictates. The L1 and L2 trigger logic can be reconfigured to optimize the system for coincidence event detection at runtime through configuration files and LabVIEW controls. This system is capable of identifying L1 triggers at at least $1$ MHz, while reading out a peak signal rate of approximately $2$ GB/s. During commissioning, the system ran at a sustained readout rate of $400$ MB/s of signal data originating from roughly $6$ kHz L2 triggers, well within the peak performance of the system.
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Submitted 24 July, 2024;
originally announced July 2024.
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Demonstration of magnetically silent optically pumped magnetometers for the TUCAN electric dipole moment experiment
Authors:
Wolfgang Klassen,
Shomi Ahmed,
Kiera Pond Grehan,
Chris Hovde,
Kirk W. Madison,
Russel R. Mammei,
Jeffery W. Martin,
Mark McCrea,
Tahereh Mohammadi,
Takamasa Momose,
Patrick Opsahl,
David C. M. Ostapchuk
Abstract:
We report the performance of a magnetically silent optically pumped cesium magnetometer with a statistical sensitivity of 3.5 pT/rtHz at 1~Hz and a stability of 90 fT over 150 seconds of measurement. Optical pumping with coherent, linearly-polarized, resonant light leads to a relatively long-lived polarized ground state of the cesium vapour contained in a measurement cell. The state precesses at i…
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We report the performance of a magnetically silent optically pumped cesium magnetometer with a statistical sensitivity of 3.5 pT/rtHz at 1~Hz and a stability of 90 fT over 150 seconds of measurement. Optical pumping with coherent, linearly-polarized, resonant light leads to a relatively long-lived polarized ground state of the cesium vapour contained in a measurement cell. The state precesses at its Larmor frequency in the magnetic field to be measured. Nonlinear magneto-optical rotation then leads to the rotation of the plane of polarization of a linearly polarized probe laser beam. The rotation angle is modulated at twice the Larmor frequency. A measurement of this frequency constitutes an absolute measurement of the magnetic field magnitude. Featuring purely optical operation, non-magnetic construction, low noise floor, and high stability, this sensor will be used for the upcoming TUCAN electric dipole moment experiment and other highly sensitive magnetic applications. Novel aspects of the system include commercial construction and the ability to operate up to 24 sensors on a single probe laser diode.
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Submitted 12 August, 2024; v1 submitted 14 May, 2024;
originally announced May 2024.
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Electric Charging Effects on Insulating Surfaces in Cryogenic Liquids
Authors:
Wolfgang Korsch,
Mark Broering,
Ashok Timsina,
Kent K. H. Leung,
Joshua Abney,
Dmitry Budker,
Bradley W. Filippone,
Jiachen He,
Suman Kandu,
Mark McCrea,
Murchhana Roy,
Christopher Swank,
Weijun Yao
Abstract:
This paper presents a new technique to study the adsorption and desorption of ions and electrons on insulating surfaces in the presence of strong electric fields in cryoliquids. The experimental design consists of a compact cryostat coupled with a sensitive electro-optical Kerr device to monitor the stability of the electric fields. The behavior of nitrogen and helium ions on a poly(methyl methacr…
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This paper presents a new technique to study the adsorption and desorption of ions and electrons on insulating surfaces in the presence of strong electric fields in cryoliquids. The experimental design consists of a compact cryostat coupled with a sensitive electro-optical Kerr device to monitor the stability of the electric fields. The behavior of nitrogen and helium ions on a poly(methyl methacrylate) (PMMA) surface was compared to a PMMA surface coated with a mixture of deuterated polystyrene and deuterated polybutadiene. Ion accumulation and removal on these surfaces were unambiguously observed. Within the precision of the data, both surfaces behave similarly for the physisorbed ions. The setup was also used to measure the (quasi-)static dielectric constant of PMMA at T = 70 K. The impact of the ion adsorption on the search for a neutron permanent electric dipole moment in a cryogenic environment, like the nEDM@SNS experiment, is discussed.
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Submitted 31 December, 2023;
originally announced January 2024.
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Precision pulse shape simulation for proton detection at the Nab experiment
Authors:
Leendert Hayen,
Jin Ha Choi,
Dustin Combs,
R. J. Taylor,
Stefan Baeßler,
Noah Birge,
Leah J. Broussard,
Christopher B. Crawford,
Nadia Fomin,
Michael Gericke,
Francisco Gonzalez,
Aaron Jezghani,
Nick Macsai,
Mark Makela,
David G. Mathews,
Russell Mammei,
Mark McCrea,
August Mendelsohn,
Austin Nelsen,
Grant Riley,
Tom Shelton,
Sky Sjue,
Erick Smith,
Albert R. Young,
Bryan Zeck
Abstract:
The Nab experiment at Oak Ridge National Laboratory, USA, aims to measure the beta-antineutrino angular correlation following neutron $β$ decay to an anticipated precision of approximately 0.1\%. The proton momentum is reconstructed through proton time-of-flight measurements, and potential systematic biases in the timing reconstruction due to detector effects must be controlled at the nanosecond l…
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The Nab experiment at Oak Ridge National Laboratory, USA, aims to measure the beta-antineutrino angular correlation following neutron $β$ decay to an anticipated precision of approximately 0.1\%. The proton momentum is reconstructed through proton time-of-flight measurements, and potential systematic biases in the timing reconstruction due to detector effects must be controlled at the nanosecond level. We present a thorough and detailed semiconductor and quasiparticle transport simulation effort to provide precise pulse shapes, and report on relevant systematic effects and potential measurement schemes.
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Submitted 6 December, 2022;
originally announced December 2022.
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The Precision nEDM Measurement with UltraCold Neutrons at TRIUMF
Authors:
Ryohei Matsumiya,
Hiroaki Akatsuka,
Chris P. Bidinosti,
Charles A. Davis,
Beatrice Franke,
Derek Fujimoto,
Michael T. W. Gericke,
Pietro Giampa,
Robert Golub,
Sean Hansen-Romu,
Kichiji Hatanaka,
Tomohiro Hayamizu,
Takashi Higuchi,
Go Ichikawa,
Sohei Imajo,
Blair Jamieson,
Shinsuke Kawasaki,
Masaaki Kitaguchi,
Wolfgang Klassen,
Emma Klemets,
Akira Konaka,
Elie Korkmaz,
Ekaterina Korobkina,
Florian Kuchler,
Maedeh Lavvaf
, et al. (23 additional authors not shown)
Abstract:
The TRIUMF Ultra-Cold Advanced Neutron (TUCAN) collaboration aims at a precision neutron electric dipole moment (nEDM) measurement with an uncertainty of $10^{-27}\,e\cdot\mathrm{cm}$, which is an order-of-magnitude better than the current nEDM upper limit and enables us to test Supersymmetry. To achieve this precision, we are developing a new high-intensity ultracold neutron (UCN) source using su…
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The TRIUMF Ultra-Cold Advanced Neutron (TUCAN) collaboration aims at a precision neutron electric dipole moment (nEDM) measurement with an uncertainty of $10^{-27}\,e\cdot\mathrm{cm}$, which is an order-of-magnitude better than the current nEDM upper limit and enables us to test Supersymmetry. To achieve this precision, we are developing a new high-intensity ultracold neutron (UCN) source using super-thermal UCN production in superfluid helium (He-II) and a nEDM spectrometer. The current development status of them is reported in this article.
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Submitted 18 July, 2022;
originally announced July 2022.
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Split Slice Training Augmentation and Hyperparameter Tuning of RAKI Networks for Simultaneous Multi-Slice Reconstruction
Authors:
Andrew S. Nencka,
PhD,
Volkan E. Arpinar,
PhD,
Sampada Bhave,
PhD,
Baolian Yang,
PhD,
Suchandrima Banerjee,
Michael McCrea,
PhD,
Nikolai J. Mickevicius,
L. Tugan Muftuler,
Kevin M. Koch
Abstract:
Split-slice augmentation for simultaneous multi-slice RAKI networks positively impacts network performance. Hyperparameter tuning of such reconstruction networks can lead to further improvements in unaliasing performance.
Split-slice augmentation for simultaneous multi-slice RAKI networks positively impacts network performance. Hyperparameter tuning of such reconstruction networks can lead to further improvements in unaliasing performance.
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Submitted 2 June, 2020;
originally announced June 2020.
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The n$^3$He Experiment: Parity Violation in Polarized Neutron Capture on $^{3}$He
Authors:
n3He Collaboration,
M. McCrea,
M. L. Kabir,
N. Birge,
C. E. Coppola,
C. Hayes,
E. Plemons,
A. Ramírez-Morales,
E. M. Scott,
J. Watts,
S. Baessler,
L. Barrón-Palos,
J. D. Bowman,
C. Britton Jr.,
J. Calarco,
V. Cianciolo,
C. B. Crawford,
D. Ezell,
N. Fomin,
I. Garishvili,
M. T. Gericke,
G. L. Greene,
G. M. Hale,
J. Hamblen,
E. Iverson
, et al. (4 additional authors not shown)
Abstract:
Significant progress has been made to experimentally determine a complete set of the parity-violating (PV) weak-interaction amplitudes between nucleons. In this paper we describe the design, construction and operation of the n$^3$He experiment that was used to measure the PV asymmetry $A_{\mathrm{PV}}$ in the direction of proton emission in the reaction…
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Significant progress has been made to experimentally determine a complete set of the parity-violating (PV) weak-interaction amplitudes between nucleons. In this paper we describe the design, construction and operation of the n$^3$He experiment that was used to measure the PV asymmetry $A_{\mathrm{PV}}$ in the direction of proton emission in the reaction $\vec{\mathrm{n}} + {^3}\mathrm{He} \rightarrow {^3}\mathrm{H} + \mathrm{p}$, using the capture of polarized cold neutrons in an unpolarized gaseous $^3\mathrm{He}$ target. This asymmetry has was recently calculated \cite{Viviani,Viviani2}, both in the traditional style meson exchange picture, and in effective field theory (EFT), including two-pion exchange. The high precision result (published separately) obtained with the experiment described herein forms an important benchmark for hadronic PV (HPV) theory in few-body systems, where precise calculations are possible. To this day, HPV is still one of the most poorly understood aspects of the electro-weak theory. The calculations estimate the size of the asymmetry to be in the range of $(-9.4 \rightarrow 3.5)\times 10^{-8}$, depending on the framework or model. The small size of the asymmetry and the small overall goal uncertainty of the experiment of $δA_{\mathrm{PV}} \simeq 1\times10^{-8}$ places strict requirements on the experiment, especially on the design of the target-detector chamber. In this paper we describe the experimental setup and the measurement methodology as well as the detailed design of the chamber, including results of Garfield++ and Geant4 simulations that form the basis of the chamber design and analysis. We also show data from commissioning and production and define the systematic errors that the chamber contributes to the measured $A_{\mathrm{PV}}$. We give the final uncertainty on the measurement.
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Submitted 22 April, 2020;
originally announced April 2020.
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The neutron electric dipole moment experiment at the Spallation Neutron Source
Authors:
K. K. H. Leung,
M. Ahmed,
R. Alarcon,
A. Aleksandrova,
S. Baeßler,
L. Barrón-Palos,
L. Bartoszek,
D. H. Beck,
M. Behzadipour,
J. Bessuille,
M. A. Blatnik,
M. Broering,
L. J. Broussard,
M. Busch,
R. Carr,
P. -H. Chu,
V. Cianciolo,
S. M. Clayton,
M. D. Cooper,
C. Crawford,
S. A. Currie,
C. Daurer,
R. Dipert,
K. Dow,
D. Dutta
, et al. (68 additional authors not shown)
Abstract:
Novel experimental techniques are required to make the next big leap in neutron electric dipole moment experimental sensitivity, both in terms of statistics and systematic error control. The nEDM experiment at the Spallation Neutron Source (nEDM@SNS) will implement the scheme of Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. The unique properties of combining polarized ultracold neutrons, polarize…
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Novel experimental techniques are required to make the next big leap in neutron electric dipole moment experimental sensitivity, both in terms of statistics and systematic error control. The nEDM experiment at the Spallation Neutron Source (nEDM@SNS) will implement the scheme of Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. The unique properties of combining polarized ultracold neutrons, polarized $^3$He, and superfluid $^4$He will be exploited to provide a sensitivity to $\sim 10^{-28}\,e{\rm \,\cdot\, cm}$. Our cryogenic apparatus will deploy two small ($3\,{\rm L}$) measurement cells with a high density of ultracold neutrons produced and spin analyzed in situ. The electric field strength, precession time, magnetic shielding, and detected UCN number will all be enhanced compared to previous room temperature Ramsey measurements. Our $^3$He co-magnetometer offers unique control of systematic effects, in particular the Bloch-Siegert induced false EDM. Furthermore, there will be two distinct measurement modes: free precession and dressed spin. This will provide an important self-check of our results. Following five years of "critical component demonstration," our collaboration transitioned to a "large scale integration" phase in 2018. An overview of our measurement techniques, experimental design, and brief updates are described in these proceedings.
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Submitted 4 October, 2019; v1 submitted 6 March, 2019;
originally announced March 2019.
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Build-A-FLAIR: Synthetic T2-FLAIR Contrast Generation through Physics Informed Deep Learning
Authors:
Andrew S. Nencka,
Andrew Klein,
Kevin M. Koch,
Sean D. McGarry,
Peter S. LaViolette,
Eric S. Paulson,
Nikolai J. Mickevicius,
L. Tugan Muftuler,
Brad Swearingen,
Michael A. McCrea
Abstract:
Purpose: Magnetic resonance imaging (MRI) exams include multiple series with varying contrast and redundant information. For instance, T2-FLAIR contrast is based upon tissue T2 decay and the presence of water, also present in T2- and diffusion-weighted contrasts. T2-FLAIR contrast can be hypothetically modeled through deep learning models trained with diffusion- and T2-weighted acquisitions.
Met…
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Purpose: Magnetic resonance imaging (MRI) exams include multiple series with varying contrast and redundant information. For instance, T2-FLAIR contrast is based upon tissue T2 decay and the presence of water, also present in T2- and diffusion-weighted contrasts. T2-FLAIR contrast can be hypothetically modeled through deep learning models trained with diffusion- and T2-weighted acquisitions.
Methods: Diffusion-, T2-, T2-FLAIR-, and T1-weighted brain images were acquired in 15 individuals. A convolutional neural network was developed to generate a T2-FLAIR image from other contrasts. Two datasets were withheld from training for validation.
Results: Inputs with physical relationships to T2-FLAIR contrast most significantly impacted performance. The best model yielded results similar to acquired T2-FLAIR images, with a structural similarity index of 0.909, and reproduced pathology excluded from training. Synthetic images qualitatively exhibited lower noise and increased smoothness compared to acquired images.
Conclusion: This suggests that with optimal inputs, deep learning based contrast generation performs well with creating synthetic T2-FLAIR images. Feature engineering on neural network inputs, based upon the physical basis of contrast, impacts the generation of synthetic contrast images. A larger, prospective clinical study is needed.
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Submitted 15 January, 2019;
originally announced January 2019.
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Measurement of the absolute neutron beam polarization from a supermirror polarizer and the absolute efficiency of a neutron spin rotator for the NPDGamma experiment using a polarized $^{3}$He neutron spin-filter
Authors:
M. M. Musgrave,
S. Baessler,
S. Balascuta,
L. Barron-Palos,
D. Blyth,
J. D. Bowman,
T. E. Chupp,
V. Cianciolo,
C. Crawford,
K. Craycraft,
N. Fomin,
J. Fry,
M. Gericke,
R. C. Gillis,
K. Grammer,
G. L. Greene,
J. Hamblen,
C. Hayes,
P. Huffman,
C. Jiang,
S. Kucuker,
M. McCrea,
P. E. Mueller,
S. I. Penttila,
W. M. Snow
, et al. (4 additional authors not shown)
Abstract:
Accurately measuring the neutron beam polarization of a high flux, large area neutron beam is necessary for many neutron physics experiments. The Fundamental Neutron Physics Beamline (FnPB) at the Spallation Neutron Source (SNS) is a pulsed neutron beam that was polarized with a supermirror polarizer for the NPDGamma experiment. The polarized neutron beam had a flux of $\sim10^9$ neutrons per seco…
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Accurately measuring the neutron beam polarization of a high flux, large area neutron beam is necessary for many neutron physics experiments. The Fundamental Neutron Physics Beamline (FnPB) at the Spallation Neutron Source (SNS) is a pulsed neutron beam that was polarized with a supermirror polarizer for the NPDGamma experiment. The polarized neutron beam had a flux of $\sim10^9$ neutrons per second per cm$^2$ and a cross sectional area of 10$\times$12~cm$^2$. The polarization of this neutron beam and the efficiency of a RF neutron spin rotator installed downstream on this beam were measured by neutron transmission through a polarized $^{3}$He neutron spin-filter. The pulsed nature of the SNS enabled us to employ an absolute measurement technique for both quantities which does not depend on accurate knowledge of the phase space of the neutron beam or the $^{3}$He polarization in the spin filter and is therefore of interest for any experiments on slow neutron beams from pulsed neutron sources which require knowledge of the absolute value of the neutron polarization. The polarization and spin-reversal efficiency measured in this work were done for the NPDGamma experiment, which measures the parity violating $γ$-ray angular distribution asymmetry with respect to the neutron spin direction in the capture of polarized neutrons on protons. The experimental technique, results, systematic effects, and applications to neutron capture targets are discussed.
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Submitted 3 April, 2018; v1 submitted 26 March, 2018;
originally announced March 2018.
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New measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission
Authors:
K. B. Grammer,
R. Alarcon,
L. Barrón-Palos,
D. Blyth,
J. D. Bowman,
J. Calarco,
C. Crawford,
K. Craycraft,
D. Evans,
N. Fomin,
J. Fry,
M. Gericke,
R. C. Gillis,
G. L. Greene,
J. Hamblen,
C. Hayes,
S. Kucuker,
R. Mahurin,
M. Maldonado-Velázquez,
E. Martin,
M. McCrea,
P. E. Mueller,
M. Musgrave,
H. Nann,
S. I. Penttilä
, et al. (3 additional authors not shown)
Abstract:
Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many body physics. Unfortunately, the pair correlation function $g(r)$ inferred from neutron scattering measurements of the differential cross section $dσ\over dΩ$ from different measu…
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Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many body physics. Unfortunately, the pair correlation function $g(r)$ inferred from neutron scattering measurements of the differential cross section $dσ\over dΩ$ from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43~meV and 16.1~meV on liquid hydrogen at 15.6~K (which is dominated by the parahydrogen component) using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1~meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra non-equilibrium component of orthohydrogen. Liquid parahydrogen is also a widely-used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. We describe our measurements and compare them with previous work.
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Submitted 24 April, 2015; v1 submitted 8 October, 2014;
originally announced October 2014.