arXiv subjects

Russell Mammei

Publications and source records attributed to Russell Mammei.

7 recordsLinked to original sources

arXiv2026

A gaseous-helium cooling system for silicon detectors in the Nab experiment

The Nab experiment aims to extract the neutron beta decay correlation coefficients 'a' and 'b'. This will be accomplished using a 7 m tall electromagnetic spectrometer which measures electron energies and proton momenta. Detection of electrons and protons resulting from neutron beta decay will be carried out using large-area, thick, highly-segmented, single-crystal silicon detectors. These detectors and accompanying electronics will be cooled by a recirculating, gaseous helium cooling system to below 150 K with +/- 0.5 K stability. We will motivate the need for detector cooling in the Nab experiment and discuss design and performance of this cooling system.

physics.ins-det↗

arXiv2025

A Novel, Steerable, Low-Energy Proton Source for Detector Characterization

We report on the conversion of the Manitoba II mass spectrometer into a versatile low-energy proton beam facility. This infrastructure is adaptable to any detector-under-test (DUT), and has proven itself effective with the characterization of silicon detectors used in subatomic beyond-the-StandardModel (BSM) searches, namely the Nab experiment. A pencil beam of monoenergetic protons can be produced in a range from 25 keV to 35 keV, achieving a beamcurrent of ~1x10-18 A. Electrostatic steering plates were constructed to direct the Gaussian-profile proton beam over a 117mm diameter areaof-interest with full-width at half-maxima (FWHM) ranging from 0.6 mm to 1.26 mm. This work discusses the modifications and subsequent tests to confirm the beam specifications met the demands of the aforementioned detectors.

physics.ins-det↗

arXiv2025

First Full Dalitz Plot Measurement in Neutron $β$-Decay using the Nab Spectrometer and Implications for New Physics

Precision measurements of observables in neutron $β$-decay are used to test the Standard Model description of the weak interaction and search for evidence of new physics. The Nab experiment at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source was constructed to measure correlations in neutron decay by utilizing an asymmetric spectrometer and novel detection system to accurately reconstruct the proton momentum and electron energy for each $β$-decay. This work describes the detection of neutron $β$-decay products in the Nab spectrometer and presents the first full Dalitz plot representation of the phase space of neutron $β$-decay for all electrons >100 keV. In addition, new constraints are placed on a possible excited neutron state, hypothesized to explain the disagreement between the appearance and disappearance neutron lifetime techniques.

nucl-ex↗

arXiv2024

QuSpin Zero-Field Magnetometer Characterization for the TUCAN Experiment

The TUCAN nEDM experiment characterizes the QuSpin Zero-Field Magnetometer (QZFM) to accurately map residual fields within a large magnetically shielded room. The magnetometer's intrinsic offset was measured to be within 3 nT and stable over a period of one year. The response was shown to be within 2 percent of linearity in the zero-field regime, up to 2 nTpp, and then follows a smooth dispersion curve. Crosstalk effects induced by multisensor operation were determined to have a small effect, and inconsequential with a separation above 6 cm. These results enable the QZFM for accurate measurement of DC fields, increase the operational range of QZFM by a factor of more than an order of magnitude, and allow for higher efficiency and flexibility by green-lighting simultaneous operation of multiple QZFMs.

physics.ins-det↗

arXiv2024

Polarized cold-neutron reflectometry at JRR-3/MINE2 for the development of ultracold-neutron spin analyzers for a neutron EDM experiment at TRIUMF

The neutron electric dipole moment (EDM) is a sensitive probe for currently undiscovered sources of charge-parity symmetry violation. As part of the TRIUMF Ultracold Advanced Neutron (TUCAN) collaboration, we are developing spin analyzers for ultracold neutrons (UCNs) to be used for a next-generation experiment to measure the neutron EDM with unprecedented precision. Spin-state analysis of UCNs constitutes an essential part of the neutron EDM measurement sequence. Magnetized iron films used as spin filters of UCNs are crucial experimental components, whose performance directly influences the statistical sensitivity of the measurement. To test such iron film spin filters, we propose the use of polarized cold-neutron reflectometry, in addition to conventional UCN transmission experiments. The new method provides information on iron film samples complementary to the UCN tests and accelerates the development cycles. We developed a collaborative effort to produce iron film spin filters and test them with cold and ultracold neutrons available at JRR-3/MINE2 and J-PARC/MLF BL05. In this article, we review the methods of neutron EDM measurements, discuss the complementarity of this new approach to test UCN spin filters, provide an overview of our related activities, and present the first results of polarized cold-neutron reflectometry recently conducted at the MINE2 beamline.

physics.ins-det↗

arXiv2022

Precision pulse shape simulation for proton detection at the Nab experiment

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.

nucl-ex↗

arXiv2022

The Precision nEDM Measurement with UltraCold Neutrons at TRIUMF

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.

physics.ins-det↗