Wed·Dec 11, 2019Wednesday·December 11, 2019

1. 01*

   Optically Pumped Cs Magnetometers Enabling a High-Sensitivity Search for the Neutron Electric Dipole Moment

   C. Abel🇬🇧 · S. Afach🇨🇭 · N. J. Ayres🇬🇧 · G. Ban🇫🇷 · G. Bison🇨🇭 · K. Bodek🇵🇱 · V. Bondar🇨🇭 · E. Chanel🇨🇭 · P.-J. Chiu🇨🇭 · C. B. Crawford🇺🇸 · Z. Chowdhuri🇨🇭 · M. Daum🇨🇭 and 48 other authors

   An array of sixteen laser-pumped scalar Cs magnetometers was part of the neutron electric dipole moment (nEDM) experiment taking data at the Paul Scherrer Institute in 2015 and 2016. It was deployed to measure the gradients of the experiment's magnetic field and to monitor their temporal evolution. The originality of the array lies in its compact design, in which a single near-infrared diode laser drives all magnetometers that are located in a high-vacuum chamber, with a selection of the sensors mounted on a high-voltage electrode. We describe details of the Cs sensors' construction and modes of operation, emphasizing the accuracy and sensitivity of the magnetic field readout. We present two applications of the magnetometer array directly beneficial to the nEDM experiment: (i) the implementation of a strategy to correct for the drift of the vertical magnetic field gradient and (ii) a procedure to homogenize the magnetic field. The first reduces the uncertainty of the new nEDM result. The second enables transverse neutron spin relaxation times exceeding 1500 s, improving the statistical sensitivity of the nEDM experiment by about 35% and effectively increasing the rate of nEDM data taking by a factor of 1.8.

   ↳ physics.atom-phhep-exnucl-exPRA(2020)·31 citations
2. 02*

   Radiogenic power and geoneutrino luminosity of the Earth and other terrestrial bodies through time

   William F. McDonough🇺🇸 · Ondřej Šrámek🇨🇿 · Scott A. Wipperfurth🇺🇸

   We report the Earth's rate of radiogenic heat production and (anti)neutrino luminosity from geologically relevant short-lived radionuclides (SLR) and long-lived radionuclides (LLR) using decay constants from the geological community, updated nuclear physics parameters, and calculations of the $\beta$ spectra. We track the time evolution of the radiogenic power and luminosity of the Earth over the last 4.57 billion years, assuming an absolute abundance for the refractory elements in the silicate Earth and key volatile/refractory element ratios (e.g., Fe/Al, K/U, and Rb/Sr) to set the abundance levels for the moderately volatile elements. The relevant decays for the present-day heat production in the Earth ($19.9\pm 3.0$ TW) are from ${}^{40}$K, ${}^{87}$Rb, ${}^{147}$Sm, ${}^{232}$Th, ${}^{235}$U, and ${}^{238}$U. Given element concentrations in kg-element/kg-rock and density $\rho$ in kg/m${}^3$, a simplified equation to calculate the present day heat production in a rock is: $$h[\mu {\text{W m}}^{-3}]=\rho \left(3.387\times 10^{-3}\text{K}+0.01139\text{Rb}+0.04595\text{Sm}+26.18\text{Th}+98.29\text{U}\right)$$ The radiogenic heating rate of Earth-like material at Solar System formation was some 10${}^3$ to 10${}^4$ times greater than present-day values, largely due to decay of ${}^{26}$Al in the silicate fraction, which was the dominant radiogenic heat source for the first $\sim 10$ Ma. Assuming instantaneous Earth formation, the upper bound on radiogenic energy supplied by the most powerful short-lived radionuclide ${}^{26}$Al ($t_{1/2}$ = 0.7 Ma) is 5.5$\times$10${}^{31}$ J, which is comparable (within a factor of a few) to the planet's gravitational binding energy.

   ↳ physics.geo-phnucl-exGeochem.Geophys.Geosyst.·14 citations
3. 03*

   Solenogam: A new detector array for $\gamma$-ray and conversion-electron spectroscopy of long-lived states in fusion-evaporation products

   Matthew Gerathy🇦🇺 · Gregory Lane · George Dracoulis · Paivi Nieminen🇫🇮 · Tibor Kibédi🇦🇺 · Matthew Reed🇦🇺 · Aqeel Akber🇦🇺 · Ben Coombes🇦🇺 · Mahananda Dasgupta · Jackson Dowie🇦🇺 · Timothy Gray🇺🇸 · David Hinde🇦🇺 and 6 other authors

   A new detector array, Solenogam, has been developed at the Australian National University Heavy Ion Accelerator Facility. Coupled initially to the SOLITAIRE 6.5 T, gas-filled, solenoidal separator, and later to an 8 T solenoid, the system enables the study of long-lived nuclear states through $\gamma$-ray and conversion-electron spectroscopy in a low-background environment. The detector system is described and results from the commissioning experiments are presented.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2020)·3 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.