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Free, publicly-accessible full text available August 17, 2025
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Free, publicly-accessible full text available April 1, 2026
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We present a method to characterize the noise in ground-based gravitational-wave observatories such as the Laser Gravitational-Wave Observatory (LIGO). This method uses linear regression algorithms such as the least absolute shrinkage and selection operator to identify noise sources and analyzes the detector output vs noise witness sensors to quantify the coupling of such noise. Our method can be implemented with currently available resources at LIGO, which avoids extra coding or direct experimentation at the LIGO sites. We present two examples to validate and estimate the coupling of elevated ground motion at frequencies below 10 Hz with noise in the detector output.more » « less
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Abstract Neutron-induced nuclear reactions play an important role in the Big Bang Nucleosynthesis. Their excitation functions are, from an experimental point of view, usually difficult to measure. Nevertheless, in the last decades, big efforts have led to a better understanding of their role in the primordial nucleosynthesis network. In this work, we apply the Trojan Horse Method to extract the cross section at astrophysical energies for the3He(n,p)3H reaction after a detailed study of the2H(3He,pt)H three-body process. Data extracted from the present measurement are compared with other published sets. The reaction rate is also calculated, and the impact on the Big Bang nucleosynthesis is examined in detail.more » « lessFree, publicly-accessible full text available November 1, 2025
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We present measurements of an optomechanical accelerometer for monitoring low-frequency noise in gravitational wave detectors, such as ground motion. Our device measures accelerations by tracking the test-mass motion of a 4.7 Hz mechanical resonator using a heterodyne interferometer. This resonator is etched from monolithic fused silica, an under-explored design in low-frequency sensors, allowing a device with a noise floor competitive with existing technologies but with a lighter and more compact form. In addition, our heterodyne interferometer is a compact optical assembly that can be integrated directly into the mechanical resonator wafer to further reduce the overall size of our accelerometer. We anticipate this accelerometer to perform competitively with commercial seismometers, and benchtop measurements show a noise floor reaching 82 pico-g Hz−1/2 sensitivities at 0.4 Hz. Furthermore, we present the effects of air pressure, laser fluctuations, and temperature to determine the stability requirements needed to achieve thermally limited measurements.more » « less
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Mattoon, C.M.; Vogt, R.; Escher, J.; Thompson, I. (Ed.)The cross-section of the thermal neutron capture41Ar(n,γ)42Ar(t1/2=32.9 y) reaction was measured by irradiating a40Ar sample at the high-flux reactor of Institut Laue-Langevin (ILL) Grenoble, France. The signature of the two-neutron capture has been observed by measuring the growth curve and identifying the 1524.6 keV γ-lines of the shorter-lived42K(12.4 h) β−daughter of42Ar. Our preliminary value of the41Ar(n,γ)42Ar thermal cross section is 240(80) mb at 25.3 meV. For the first time, direct counting of42Ar was performed using the ultra-high sensitivity technique of noble gas accelerator mass spectrometry (NOGAMS) at Argonne National Laboratory, USA.more » « less
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Freeman, S.; Lederer-Woods, C.; Manna, A.; Mengoni, A. (Ed.)The thermodynamical conditions and the neutron density produced in a laser-induced implosion of a deuterium-tritium (DT) filled capsule at the National Ignition Facility (NIF) are the closest laboratory analog of stellar conditions. We plan to investigate neutron-induced reactions on 40 Ar, namely the 40 Ar( n , 2 n ) 39 Ar( t 1/2 =268 y), the 40 Ar( n , γ) 41 Ar(110 min) and the potential rapid two-neutron capture reaction 40 Ar(2 n , γ) 42 Ar(33 y) in an Ar-loaded DT capsule. The chemical inertness of noble gas Ar enables reliable collection of the reaction products.more » « less