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Ben Ohayon

Publications and source records attributed to Ben Ohayon.

30 records · Page 2Linked to original sources
arXiv2022

Muonic-Atom Spectroscopy and Impact on Nuclear Structure and Precision QED Theory

Recent progress in laser and x-ray spectroscopy of muonic atoms offers promising long-term possibilities at the intersection of atomic, nuclear and particle physics. In muonic hydrogen, laser spectroscopy measurements will determine the ground-state hyperfine splitting (HFS) and additionally improve the Lamb shift by a factor of 5. Precision spectroscopy with cryogenic microcalorimeters has the potential to significantly improve the charge radii of the light nuclei in the $Z=3-8$ range. Complementary progress in precision should be achieved on the theory of nucleon- and nuclear-structure effects. The impact of this muonic-atom spectroscopy program will be amplified by the upcoming results from H and He$^+$ spectroscopy, simple molecules such as HD$^+$ and Penning trap measurements. In this broader context, one can test ab-initio nuclear theories, bound-state QED for two- or three-body systems, and determine fundamental constants, such as the Rydberg ($R_\infty$) and the fine-structure ($α$) constants.

nucl-th↗
arXiv2022

High-resolution isotope-shift spectroscopy of Cd I

We present absolute frequency measurements of the ${}^{1}\text{P}_1 \leftarrow {}^{1}\text{S}_0$ ($229$nm) and ${}^{3}\text{P}_1 \leftarrow {}^{1}\text{S}_0$ ($326$nm) transitions for all naturally occurring isotopes of cadmium. The isotope shifts and hyperfine intervals of the fermionic isotopes are determined with an accuracy of 3.3MHz. We find that quantum interference in the laser-induced fluorescence spectra of the ${}^{1}\text{P}_1 \leftarrow {}^{1}\text{S}_0$ transition causes an error of up to 29(5)MHz in determining the hyperfine splitting, when not accounted for with an appropriate model. Using a King-plot analysis, we extract the field- and mass-shift parameters and determine nuclear charge radius differences for the fermions. The lifetime of the $^1\text{P}_1$ state is determined to be 1.60(5)ns by measuring the natural linewidth of the ${}^{1}\text{P}_1 \leftarrow {}^{1}\text{S}_0$ transition. These results resolve significant discrepancies among previous measurements.

physics.atom-ph↗
arXiv2022

Towards an independent determination of muon g-2 from muonium spectroscopy

We show that muonium spectroscopy in the coming years can reach a precision high enough to determine the anomalous magnetic moment of the muon below one part per million (ppm). Such an independent determination of muon g-2, which is not limited by hadronic uncertainties, would certainly shed light on the 2ppm difference currently observed between spin-precession measurements and (R-ratio based) Standard Model predictions. The magnetic dipole interaction between electrons and (anti)muons bound in muonium gives rise to a hyperfine splitting (HFS) of the ground state which is sensitive to the muon anomalous magnetic moment. A direct comparison of the muonium frequency measurements of the HFS at J-PARC and the 1S-2S transition at PSI with theory predictions will allow to extract muon g-2 with high precision. Improving the accuracy of QED calculations of these transitions by about one order of magnitude is also required. Moreover, the good agreement between theory and experiment for the electron g-2 indicates that new physics interactions are unlikely to affect muonium spectroscopy down to the envisaged precision.

hep-ph↗
arXiv2021

Muonium Lamb shift: theory update and experimental prospects

We review the theory of the Lamb shift for muonium, provide an updated numerical value and present the prospects of the Mu-MASS collaboration at PSI to improve upon their recent measurement. Due to its smaller nuclear mass, the contributions of the higher-order recoil corrections (160kHz level) and nucleus self-energy 40kHz level) are enhanced for muonium compared to hydrogen where those are below the level of the latest measurement performed by Hessels et al. and thus could not be tested yet. The ongoing upgrades to the Mu-MASS setup will open up the possibility to probe these contributions and improve the sensitivity of this measurement to searches for new physics in the muonic sector.

physics.atom-ph↗
arXiv2021

Constraining new physics with a novel measurement of the $^{23}$Ne $β$-decay branching ratio

Measurements of the beta-neutrino correlation coefficient (a$_{βν}$) in nuclear beta decay, together with the Fierz interference term (b$_F$), provide a robust test for the existence of exotic interactions beyond the Standard Model of Particle Physics. The extraction of these quantities from the recoil ion spectra in $β$-decay requires accurate knowledge, decay branching ratios, and high-precision calculations of higher order nuclear effects. Here, we report on a new measurement of the $^{23}$Ne $β$-decay branching ratio, which allows a reanalysis of existing high-precision measurements. Together with new theoretical calculations of nuclear structure effects, augmented with robust theoretical uncertainty, this measurement improves on the current knowledge of a$_{βν}$ in $^{23}$Ne by an order of magnitude, and strongly constrains the Fierz term in beta decays, making this one of the first extractions to constrain both terms simultaneously. Together, these results place bounds on the existence of exotic tensor interactions and pave the way for new, even higher precision, experiments.

nucl-ex↗
arXiv2021

Stable High Power deep-UV Enhancement Cavity in Ultra High Vacuum with Fluoride Coatings

We demonstrate the superior performance of fluoride coated versus oxide coated mirrors in long term vacuum operation of a high power deep-ultraviolet enhancement cavity. In high vacuum ($10^{-8}$ mbar), the fluoride optics can maintain up to a record-high 10 w of stable intracavity power on one hour time scales, whereas for the oxide optics, we observe rapid degradation at lower intracavity powers with a rate that increases with power. After observing degradation in high vacuum, we can recover the fluoride and oxide optics with oxygen; however, this recovery process becomes ineffective after several applications. For fluoride coatings, we see that initial UV conditioning in an oxygen environment helps to improve the performances of the optics. In oxygen-rich environments from $\sim 10^{-4}$ mbar to 1 mbar, the fluoride optics can stably maintain up to 20 W of intracavity power on several-hour time scales whereas for the oxide optics there is immediate degradation with a rate that increases with decreasing oxygen pressure.

physics.optics↗
arXiv2020

$^{23}$Ne Production at SARAF-I

In this article, we present a measurement of flow rate, yield and effusion time of a $^{23}$Ne production and transport system. We used an accelerator-driven Li(d,n) neutron source to produce neutrons up to 20 MeV. The radioactive atoms were produced by a $^{23}$Na(n,p) reaction at a NaCl target. Later, the atoms were diffused out from the NaCl crystals and effused from the production chamber via a 10 m hose to a measurement cell and their decay products were detected using high purity germanium (HPGe) and plastic scintillator detectors. The resulting flow rate was $6.9\pm0.5\cdot 10^4\sfrac{atoms}{sec}$ and the total yield was $3.2\pm0.4\cdot10^{-9}\sfrac{atoms}{deuteron}$. We summarize our methods and estimates of efficiencies, rates of production and effusion.

nucl-ex↗
arXiv2020

A decay microscope for trapped neon isotopes

We review the design, simulation, and tests, of a detection system for measuring the energy distribution of daughter nuclei recoiling from the beta-decay of laser trapped neon isotopes. This distribution is sensitive to several new physics effects in the weak sector. Our `decay microscope' relies on imaging the velocity distribution of high energy recoil ions in coincidence with electrons shaken-off in the decay. We demonstrate by way of Monte-Carlo simulation, that the nuclear microscope increases the statistical sensitivity of kinematic measurements to the underlying energy distribution, and limits the main systematic bias caused by discrepancy in the trap position along the detection axis.

physics.ins-det↗
arXiv2019

Weak interaction studies at SARAF

We review the current status of the radioisotopes program at the Soreq Applied Research Accelerator Facility (SARAF), where we utilize an electrostatic-ion-beam trap and a magneto-optical trap for studying the nuclear $β$-decay from trapped radioactive atoms and ions. The differential energy spectra of $β$'s and recoil ions emerging from the decay is sensitive to beyond standard model interactions and is complementary to high energy searches. The completed facility SARAF-II will be one of the world's most powerful deuteron, proton and fast neutron sources, producing light radioactive isotopes in unprecedented amounts, needed for obtaining enough statistics for a high precision measurement.

nucl-ex↗
arXiv2018

The Soreq Applied Research Accelerator Facility (SARAF) - Overview, Research Programs and Future Plans

The Soreq Applied Research Accelerator Facility (SARAF) is under construction in the Soreq Nuclear Research Center at Yavne, Israel. When completed at the beginning of the next decade, SARAF will be a user facility for basic and applied nuclear physics, based on a 40 MeV, 5 mA CW proton/deuteron superconducting linear accelerator. Phase I of SARAF (SARAF-I, 4 MeV, 2 mA CW protons, 5 MeV 1 mA CW deuterons) is already in operation, generating scientific results in several fields of interest. The main ongoing program at SARAF-I is the production of 30 keV neutrons and measurement of Maxwellian Averaged Cross Sections (MACS), important for the astrophysical s-process. The world leading Maxwellian epithermal neutron yield at SARAF-I ($5\times 10^{10}$ epithermal neutrons/sec), generated by a novel Liquid-Lithium Target (LiLiT), enables improved precision of known MACSs, and new measurements of low-abundance and radioactive isotopes. Research plans for SARAF-II span several disciplines: Precision studies of beyond-Standard-Model effects by trapping light exotic radioisotopes, such as $^6$He, $^8$Li and $^{18,19,23}$Ne, in unprecedented amounts (including meaningful studies already at SARAF-I); extended nuclear astrophysics research with higher energy neutrons, including generation and studies of exotic neutron-rich isotopes relevant to the rapid (r-) process; nuclear structure of exotic isotopes; high energy neutron cross sections for basic nuclear physics and material science research, including neutron induced radiation damage; neutron based imaging and therapy; and novel radiopharmaceuticals development and production. In this paper we present a technical overview of SARAF-I and II, including a description of the accelerator and its irradiation targets; a survey of existing research programs at SARAF-I; and the research potential at the completed facility (SARAF-II).

physics.ins-det↗
arXiv2013

New Approaches in designing a Zeeman-Slower

We present two new approaches for the design of a Zeeman-Slower, which rely on optimal compliance with the adiabatic following condition and are applicable to a wide variety of systems. The first approach is an analytical one, based on the assumption that the noise in the system is position independent. When compared with the traditional approach, which requires constant deceleration, for a typical system, we show an improvement of $\sim$ 10% in the maximal capture velocity, allowing for a larger slower acceptance, or a reduction of $sim$ 25% in slower length, allowing for a simpler design and a better collimated beam. The second approach relies on an optimization of a system in which the magnetic field and the noise profile are well known. As an example, we use our 12-coil modular design and show an improvement of $sim$ 9% in maximal capture velocity or, alternatively, a reduction of $\sim$ 33% in slower length as compared with the traditional approach.

physics.atom-ph↗