Xe Targets Research Articles

Migdal-type effect in the dark matter absorption process

We propose a new mechanism of absorption of dark matter particles in atoms which resembles the Migdal effect of inelastic dark matter scattering. In this process, atoms may be ionized upon absorption of a scalar particle through the scalar-nucleon Yukawa-type interaction. The crucial difference from the inelastic dark matter scattering on atoms is that the total energy of the particle, including its rest mass mc2 term, is transferred to the electron. As a result, the emitted electron kinetic energy is about 6 orders in magnitude bigger than that in the dark matter scattering process. This absorption process allows one to probe dark matter particles with a relatively small mass, in the range from 1 to 100 keV, that cannot be detected in the scattering process. It is also possible to detect hypothetical scalar particles emitted from the Sun. We calculate absorption cross sections of this process in Na, Si, Ar, Ge, I, Xe, and Tl target atoms and extract limits on the scalar-nucleon interaction constant from null results of the XENONnT experiment. Published by the American Physical Society 2024

Laser-excited Xe plasma as a radiation source for lithography at wavelengths near 11 nm

Subject of study. The study focuses on the plasma excited by a laser on a gas-jet Xe target. Aim of study. The aim was to achieve such a high emissivity of the Xe plasma at a wavelength of 11.2 nm that would meet the requirements of industrial lithography. In addition to the applied aspect, the work also has a diagnostic component, the purpose of which is to study the internal structure of the laser plasma and determine its internal parameters, such as temperature, concentration, and mean ion charge. Method. The paper contains a review of works devoted to the comprehensive investigation of the laser-produced plasma with a Xe gas-jet target. In the course of this research, several methods of measurements and plasma diagnostics were developed and tested, including multimirror Bragg spectrometry, probing the plasma with the same infrared laser radiation that creates it, and determination of mean ion charge of this nonequilibrium and short-lived laser-produced plasma using the measured absorption of the laser energy in the plasma and a database on cross-sections of ionization by electron impact. Main results. A multimirror Bragg spectrometry technique was developed and tested. This technique was then used to obtain quantitatively calibrated spectra of the laser-produced Xe plasma. An effective mode of irradiating the target with a wide, defocused laser beam has been found, which made it possible to achieve the coefficient of conversion of laser pulse energy into the energy of the narrow-band plasma radiation around λ=11.2nm, approximately equal to 4%. This value is currently a world record for plasmas of such a type. Additionally, an analytical method for determining the temperature and ion charge of the plasma based on experimental measurements was developed. Practical significance. The achieved conversion efficiency of the radiation source under consideration is sufficient for its application in high production industrial lithography. The use of the simple and “clean” radiation source with Xe plasma could eliminate a number of problems encountered in contemporary lithography with a wavelength of 13.5 nm and a source with targets of metallic tin.

Impact of nuclear structure from shell model calculations on nuclear responses to WIMP elastic scattering for $^{19}$F and $^{nat}$Xe targets

Non-relativistic effective field theory (NREFT) is one approach used for describing the interaction of WIMPs with ordinary matter. Among other factors, these interactions are expected to be affected by the structure of the atomic nuclei in the target. The sensitivity of the nuclear response components of the WIMP-nucleus scattering amplitude is investigated using shell model calculations for ^{19}19F and ^{nat}natXe. Resulting integrated nuclear response values are shown to be sensitive to some specifics of the nuclear structure calculations.

Nuclear response to dark matter signals in Ge and Xe odd-mass targets

The interaction of dark matter particles (weakly interacting massive particles (WIMPs)) with the odd-mass [Formula: see text]Ge and [Formula: see text]Xe target nuclei, that is, the recoil rates corresponding to the elastic scattering of WIMPs by these nuclei, is analyzed in the context of the minimal extensions of the supersymmetry model. The BCS+QRPA technique plus the quasiparticle–phonon coupling scheme is used to describe the nuclear structure part of the calculations. The resulting values for the nuclear spin content of both nuclei are compared to values previously reported in the literature.

Spatial and spectral variations of high-order harmonics generated in noble gases

We report on the spatial and spectral variation of high-order harmonics generation from noble gases when driven by high-repetition rate femtosecond laser with different peak intensity and polarization states. Ar, Xe, and Kr were chosen for the generation of coherent extreme ultraviolet radiation. We observe that increasing the intensity of the driving pulses (DPs) leads to disappearance of harmonics yield in the on-axis part of the spatial distribution of the harmonics in Xe target, contrary to Ar and Kr. This observation is attributed to the higher ionization potential of the latter gases. Spectral depletion of harmonics generated in Ar and Xe using radially and azimuthally polarized Gaussian–Laguerre two-color DPs is also observed. The significant depletion in the spectral distribution of harmonics is obtained when two-color pump (TCP) scheme is applied. We demonstrate how TCP scheme with azimuthally polarized DPs can be used as a tool to control the spectral distribution of harmonics generated from gas atoms during strong field by utilizing the presence of second harmonic electromagnetic field.

Electron-loss-to-continuum cusp in collisions of U89+ with N2 and Xe

We study the electron-loss-to-continuum (ELC) cusp experimentally and theoretically by comparing the ionization of U$^{89+}$ projectiles in collisions with N$_2$ and Xe targets, at a beam energy of 75.91 MeV/u. The coincidence measurement between the singly ionized projectile and the energy of the emitted electron is used to compare the shape of the ELC cusp at weak and strong perturbations. A significant energy shift for the centroid of the electron cusp is observed for the heavy target of Xe as compared to the light target of N$_2$. Our results provide a stringent test for fully relativistic calculations of double-differential cross sections performed in the first-order approximation and in the continuum-distorted-wave approach.

Alignment of the projectile 2p3/2 state created by nonradiative electron capture in 95- and 146-MeV/u Xe54+ with Kr and Xe collisions

Anisotropic distributions of the Lyman-${\ensuremath{\alpha}}_{1}$ transition of the down-charged $\mathrm{X}{\mathrm{e}}^{53+*}$ ions are observed in fast $\mathrm{X}{\mathrm{e}}^{54+}$ with Kr and Xe collisions, in which the electron is transferred by the nonradiative electron capture mechanism. At the energy of 95 MeV/u, the alignment parameter of the projectile $2{p}_{3/2}$ state, ${\mathcal{A}}_{20}$, is determined to be \ensuremath{-}0.35 \ifmmode\pm\else\textpm\fi{} 0.02 for both targets. While the projectile energy is 146 MeV/u, the parameter for the Kr and Xe target is \ensuremath{-}0.28 \ifmmode\pm\else\textpm\fi{} 0.02 and \ensuremath{-}0.29 \ifmmode\pm\else\textpm\fi{} 0.04, respectively. The present results demonstrate that the electron capture to the ${m}_{j}=\ifmmode\pm\else\textpm\fi{}1/2$ magnetic substates is about two times more probable than to the ${m}_{j}=\ifmmode\pm\else\textpm\fi{}3/2$ ones.

Characterization of plasma emission in the 1-6 nm band from laser-irradiated cryogenic xenon targets

We present measurements from laser-produced plasmas generated using cryogenic Xe targets and quantify the emission characteristics in the soft x-ray region (1 to 6 nm). The system is based on a LN2-cooled rotating drum, which allows for a high repetition rate, and Nd:YAG laser systems with energies up to 325 mJ on-target with pulse lengths of 130 ps, 600 ps, or 6.5 ns. High resolution spectra are measured using a grazing incidence spectrometer, and we present the first quantitative conversion efficiency (CE) measurements for Xe in this range. Data show CE values up to ∼1% at 6 nm and ∼0.08% at 1.5 nm (for 2% bandwidth and 2π solid angle), and there are lower limits on the required laser intensities and energies on target to achieve these efficiencies. In addition, the emission spot size is directly measured at 2 nm (620 eV) using a point-projection slit imaging method, with optimized emission spot sizes of ∼20 μm.

Medium-indused modification of kaons spectra measured in SIDIS at HERMES

The predicted high sensitivity of the nuclear modification factor for K– in SIDIS due to the QCD based effect of medium-induced flavour conversion in the fragmentation function is studied at HERMES experiment. Unlike π+, π– and K+ nuclear modification factor for K– is assumed to increase at high value of Bjorken variable xB and a hadron fraction energy z. The experimental signature of this phenomenon is an enhanced K– nuclear modification factor compared with those of K+ for high xB and z range. The z spectra of nuclear attenuation ratios for charged kaons in different slices of xB extracted on Ne, Kr and Xe targets will be presented and discussed.

Laser plasma vacuum ultraviolet light source using solid rare-gas targets

The laser plasma emission spectra in a broadband from 30 to 200 nm of solid Ar, Kr, and Xe targets are presented for the first time. The spectra are composed of a broadband continuum and lines. A broadband vacuum ultraviolet (VUV) spectrometer that can measure spectra in the wavelength range from 30 to 200 nm is developed and the measured spectra are able to be calibrated over the entire broad band. The spectral intensity integrated from 30 to 200 nm indicates that the VUV average power generated in the wavelength range is 30 mW when the laser energy is 1 J at 1 Hz. The number of photons of monochromatic light after passing through the spectrometer is estimated to be more than 5 × 106 photons/nm/pulse over the wavelength range and is considered to be useful for applications of broadband VUV spectroscopy.

Solar neutrinos as a signal and background in direct-detection experiments searching for sub-GeV dark matter with electron recoils

Direct-detection experiments sensitive to low-energy electron recoils from sub-GeV dark matter (DM) interactions will also be sensitive to solar neutrinos via coherent neutrino-nucleus scattering (CNS), since the recoiling nucleus can produce a small ionization signal. Solar neutrinos constitute both an interesting signal in their own right and a potential background to a DM search that cannot be controlled or reduced by improved shielding, material purification and handling, or improved detector design. We explore these two possibilities in detail for semiconductor (Si and Ge) and Xe targets, considering several possibilities for the unmeasured ionization efficiency at low energies. For DM-electron-scattering searches, neutrinos start being an important background for exposures larger than ~1-10 kg-years in Si and Ge, and for exposures larger than ~0.1-1 kg-year in Xe. For the absorption of bosonic DM (dark photons and axion-like particles) by electrons, neutrinos are most relevant for masses below ~1 keV and again slightly more important in Xe. Treating the neutrinos as a signal, we find that the CNS of B-8 neutrinos can be observed with ~2 sigma significance with exposures of ~2, 7, and 20 kg-years in Xe, Ge, and Si, respectively, assuming there are no other backgrounds. We give an example for how this would constrain non-standard neutrino interactions. Neutrino components at lower energy can only be detected if the ionization efficiency is sufficiently large. In this case, observing pep neutrinos via CNS requires exposures ~10-100 kg-years in Si or Ge (~1000 kg-years in Xe), and observing CNO neutrinos would require an order of magnitude more exposure. Only Si could potentially detect Be-7 neutrinos. These measurements would allow for a direct measurement of the electron-neutrino survival probability over a wide energy range.

Effect of hydrodynamical-simulation–inspired dark matter velocity profile on directional detection of dark matter

Directional detection is an important way to detect dark matter. An input to these experiments is the dark matter velocity distribution. Recent hydrodynamical simulations have shown that the dark matter velocity distribution differs substantially from the Standard Halo Model. We study the impact of some of these updated velocity distribution in dark matter directional detection experiments. We calculate the ratio of events required to confirm the forward-backward asymmetry and the existence of the ring of maximum recoil rate using different dark matter velocity distributions for $^{19}$F and Xe targets. We show that with the use of updated dark matter velocity profiles, the forward-backward asymmetry and the ring of maximum recoil rate can be confirmed using a factor of $\sim$2 - 3 less events when compared to that using the Standard Halo Model.

Study of Ion Dynamics by Electron Transfer Dissociation: Alkali Metals as Targets.

High energy collision processes for singly charged positive ions using an alkali metal target are confirmed, as a charge inversion mass spectrometry, to occur by electron transfers in successive collisions and the dissociation processes involve the formation of energy-selected neutral species from near-resonant neutralization with alkali metal targets. A doubly charged thermometer molecule was made to collide with alkali metal targets to give singly and doubly charged positive ions. The internal energy resulting from the electron transfer with the alkali metal target was very narrow and centered at a particular energy. This narrow internal energy distribution can be attributed to electron transfer by Landau-Zener potential crossing between the precursor ion and an alkali metal atom, and the coulombic repulsion between singly charged ions in the exit channel. A large cross section of more than 10-14 cm2 was estimated for high-energy electron transfer dissociation (HE-ETD). Doubly protonated phosphorylated peptides obtained by electrospray ionization were collided with Xe and Cs targets to give singly and doubly charged positive ions. Whereas doubly charged fragment ions resulting from CAD were dominant in the case of the Xe target, singly charged fragment ions resulting from ETD were dominant with the Cs target. HE-ETD using the Cs target provided all of the z-type ions by N-Cα bond cleavage without the loss of the phosphate groups. The results demonstrate that HE-ETD with an alkali metal target allowed the position of phosphorylation and the amino acid sequence of peptides with post translational modifications (PTM) to be determined.

Absorption of the laser radiation by the laser plasma with gas microjet targets

An upper limit of absorption of the laser radiation in the plasma produced in a gas jet Xe target with the average density of (3–6) × 1018 cm–3 and the effective diameter of 0.7 mm is found. It is equal to ≈50% and remains constant under any variation in this range of densities. This result contradicts both theoretical assessments that have predicted virtually complete absorption and results of earlier experiments with the laser spark in an unlimited stationary Xe gas with the same density, where the upper limit of absorption was close to 100%. An analysis shows that nonlinearity of absorption and plasma nonequilibrium lead to the reduction of the absorption coefficient that, along with the limited size of plasma, can explain the experimental results.

Antiproton stopping in atomic targets

Stopping powers of antiprotons in H, He, Ne, Ar, Kr, and Xe targets are calculated using a semiclassical time-dependent convergent close-coupling method. The helium target is treated using both frozen-core and multiconfiguration approximations. The electron-electron correlation of the target is fully accounted for in both cases. Double ionization and ionization with excitation channels are taken into account using an independent-event model. The Ne, Ar, Kr, and Xe atom wave functions are described in a model of six $p$-shell electrons above a frozen Hartree-Fock core with only one-electron excitations from the outer $p$ shell allowed. Results obtained for helium in the multiconfiguration treatment are in better agreement with experimental measurements than other theories.

Stopping and Straggling of Swift Hydrogen-Dicluster Ions Using Energy-Loss Function of Harmonic Oscillator Model

In the present work we analyze our theoretical investigation of various aspects of the random and aligned stopping power of hydrogen-dicluster H_2^+ moving in close but variable vicinity of each other in a dilute and dense stopping targets, which being modeled by a harmonic oscillator (HO) with generalized oscillator strength (GOS).This model combined with a free electron gas (FEG) using dielectric theory to calculate the energy loss function (ELF) of dense medium which treated by harmonic oscillator model. We have made comprehensive investigation of single and vicinage stopping power, and related quantities for hydrogen-dicluster ions H_2^+ in (C, Al, Ar and Xe) targets.

Usefulness of nano-zirconia for purification and concentration of 125I solution for medical applications

This paper described the utility of tetragonal nano-zirconia (t-ZrO2) to remove trace levels of 134Cs and 137Cs contaminants from 125I solution obtained from neutron irradiation of natural Xe target. A careful scrutiny of the adsorption parameters of t-ZrO2 was considered worthwhile investigating to arrive at the optimum conditions to perform the purification as well as concentration of 125I solution. The procedure proposed herein provides 125I of acceptable purity and radioactive concentration for clinical application. The compatibility of the separated product in the preparation of 125I brachytherapy sources was found to be satisfactory.

Comparative analysis of stable ultrahigh power-density 248 nm channels formed in Kr and Xe cluster targets

Comparative single-pulse studies of self-trapped plasma channel formation in Xe and Kr cluster targets produced with 1–2 TW femtosecond 248 nm pulses reveal energy efficient channel formation (>90%) and highly robust stability for the channeled propagation in both materials. Images of the channel morphology produced by Thomson scattering from the electron density and direct visualization of the Xe(M) and Kr(L) x-ray emission from radiating ions illustrate the (1) channel formation, (2) the narrow region of confined trapped propagation, (3) the abrupt termination of the channel that occurs at the point the power falls below the critical power Pcr, and, in the case of Xe channels, (4) the presence of saturated absorption of Xe(M) radiation that generates an extended peripheral zone of ionization. The measured rates for energy deposition per unit length are ∼ 1.46 J cm−1 and ∼ 0.82 J cm−1 for Xe and Kr targets, respectively, and the single pulse Xe(M) energy yield is estimated to be > 50 mJ, a value indicating an efficiency >20% for ∼ 1 keV x-ray production from the incident 248 nm pulse.

Diamond-like carbon sputtering by laser produced Xe plasma

The sputtering of diamond-like carbon (DLC) was investigated using Xe ion bombardment from the laser plasma X-ray source (LPX). The LPX we developed uses a solid Xe target and emits UV–X-rays and Xe ions. Using the LPX as an ion source, we measured etching depths of DLC, Ru, and Au films using a quartz crystal microbalance (QCM) to determine their ion sputtering rates at incident angles of 0° and 70°. The calculated results by the SRIM code were able to predict the measured results, except for the case of the DLC film at 0° incident. Our measured result indicated that the DLC sputtering at 0° was ten times larger than previously reported data, in which an ion gun was used. We consider that the difference was a characteristic effect of the laser plasma, and can be explained as a synergistic effect of ion bombardment and UV radiation from the Xe plasma.

Ionization of noble gas by impact of hydrogen anions

Relative cross-sections for double ionization and single ionization of targets under the impact of hydrogen anions were measured. Two systems were investigated, H− projectiles with Kr and Xe targets. The energy region was 10–30 keV. Recoil ions originated from target (Kr+, Kr2+, Xe+, Xe2+) were detected in coincidence with projectiles in several final charge states (q = 0 and q = + 1). We compare the present results with the previous results of Ar. The results show that the cross-section ratios, taken between double and single ionization of Ar, Kr and X in the channels of single and double electron loss of H−, become larger and larger with the incident energy increasing, and that the cross-section ratios will cross at some certain energy for the two different electron loss channels. The crossing energy for Xe is about 23 keV.