H2 Gas Targets Research Articles

Neutron radius determination of 133Cs and its impact on the interpretation of CEνNS-CsI measurement

Proton-133Cs elastic scattering at low momentum transfer is performed using an in-ring reaction technique at the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou. Recoil protons from the elastic collisions between the internal H2-gas target and the circulating 133Cs ions at 199.4 MeV/u are detected by a silicon-strip detector. The matter radius of 133Cs is deduced by describing the measured differential cross sections using the Glauber model. Employing the adopted proton distribution radius, a point-neutron radius of 4.86(21) fm for 133Cs is obtained. With the newly determined neutron radius, the weak mixing angle sinθW2 is independently extracted to be 0.227(28) by fitting the coherent elastic neutrino-nucleus scattering data. Our work limits the sinθW2 value in a range smaller than the ones proposed by the previous independent approaches, and would play an important role in searching new physics via the high precision CEνNS-CsI cross section data in the future.

Analytical solution versus the Monte Carlo simulation for studying the H+ beam neutralization in H2 gas target neutralizer

A comparative Study on the conversion of an energetic H+ beam inside a cell neutralizer filled with hydrogen gas target is conducted by two different methods to determine the maximum beam neutralization efficiency and corresponding optimal gas thickness in terms of beam energy, ranging from 1 keV to 10 MeV. One method analytically solves the equations of particle flux with a deterministic response. The other uses the random collisional probability based on the Monte Carlo simulation with non-deterministic response, which is implemented by COMSOL software. Effective reactions of charge exchange and reionization are commonly considered in both methods with the energy-depended collisional cross section. The results obtained from the two methods are compared, demonstrating good fitness with a mean difference of ±1.5 %. This acceptive difference arises often due to statistical errors that occur in the Monte Carlo calculations. Additionally, a close agreement is found between calculated and measured efficiencies.

Luminescence cross sections in the low-energy collisions of H+, H2+, and H3+ ions with H2

Luminescence cross sections for the optical emission of molecular hydrogen in the 200–600 nm spectral range and for the atomic Balmer-β line were measured for low-energy ( ≤1 keV) H+, H2+, and H3+ ions colliding with H2 gas targets. Molecular hydrogen transitions between singlet states were observed for all the systems studied, while the emission continuum H2(a-b) and discrete spectra associated with other transitions between triplet states appeared only in the H2+ + H2 collisions, where the spin conservation rule is fulfilled. Isotopic substitutions in the H2+/D2+ + H2, D2 system show that at Elab = 1 keV, a dominant molecular luminescence mechanism is the collision-induced excitation (CIE) of the target.Graphical abstract

Prompt Emission in Fission Induced with Fast Neutrons

Prompt gamma-ray and neutron emission data in fission integrates a large amount of information on the fission process and can shed light on the partition of energy. Measured emission spectra, average energies and multiplicities also provide important information for energy applications. While current reactors mostly use thermal neutron spectra, the future reactors of Generation IV will use fast neutron spectra for which little experimental prompt emission data exist.Initial investigations on prompt emission in fast neutron induced fission have recently been carried out at the LICORNE facility at the IPN Orsay, which exploits inverse reactions to produce naturally collimated, intense beams of neutrons. We report on first results with LICORNE to measure prompt fission gamma-ray spectra, average energies and multiplicities for 235U and 238U. Current improvements and upgrades being carried out on the LICORNE facility will also be described, including the development of a H2 gas target to reduce parasitic backgrounds and increase intensities, and the deployment of 11B beams to extend the effective LICORNE neutron energy range up to 12 MeV. Prospects for future experimental studies of prompt gamma-ray and neutron emission in fast neutron induced fission will be presented.

Luminescent collisions of He+ and He++ ions with H2 molecules at energies below 2 keV

Spectroscopic studies of collisions between He+ and He++ ions with H2 gas target have been performed in the 200–600 nm wavelength range. Atomic lines of hydrogen Balmer series and several helium lines were identified and their excitation functions between 50 eV and 1 keV (2 keV for He++) were determined.

Relative densities of hydrogen ion species in a hollow cathode glow discharge

Highly resolved Doppler shifted peaks of the hydrogen Balmer lines, resulting from charge exchange of H+, H2 +, and H3 + with an H2 gas target, were obtained without the need for a deconvolution procedure. This enabled the unambiguous determination of the chemistry of these hydrogen species in the units of mTorr pressure range. This was obtained from a gaseous discharge using a biconical hollow cathode that yielded a well collimated and monoenergetic beam.

Production of an 8.0 MeV 7Be ion beam at the Naples TTT-3 accelerator

For an improved determination of the 7Be(p, γ)8B absolute cross section, the reaction is studied in inverse kinematics. The study involves a 7Be radioactive ion beam of 8.0 MeV, a windowless H2 gas target, and an efficient recoil separator for the detection of the 8B residual nuclides. The techniques used to produce such a beam as well as the first direct observation of 8B are reported.

Collision spectroscopy of low-energy-beam U^5+ ions

The sixth spectrum of uranium (U vi) between 80 and 115 nm is studied by observation of transitions following low-energy electron capture by a U6+-ion beam in a H2 gas target. Emission cross sections of several identified transitions are obtained, the energy dependence investigated, and the spectra compared with the predictions of single-configuration Dirac–Fock (SCDF) calculations. Based on tentative identifications, a Rydberg–Ritz parameterization yields a predicted ionization potential only 0.3% above the SCDF result.

Antiproton-proton annihilation at rest in H2 gas into π+ π− π0

Antiproton-proton annihilation at rest into π+ π− π0 has been studied by stopping antiprotons from LEAR in a H2 gas target at normal temperature and pressure. The reaction is observed in coincidence withL X-rays which are emitted in the cascade of\(\bar pp\) atoms. The X-rays populate one of the angular momentumL=1 states of a\(\bar pp\) atom which then annihilates. A spinparity analysis of the π+ π− π0 Dalitz plot gives contributions from the threeP states from which annihilation into three pions is allowed. The most striking features of the Dalitz plot are production of charged and neutral ϱ(770) and off2(1270) mesons. Production of ϱ(770) mesons proceeds via the isoscalar part of the1P1 state and the isovector part of the3P1 state.f2(1270) mesons are produced abundantly fromP states while their production fromS states is very weak. The π+ π− invariant mass spectrum shows a third strong peak at a mass of 1565±20 MeV/c2 and a width of 170±40 MeV/c2, which we call AX(1565). No reasonable description of the Dalitz plot is obtained without introducing the AX(1565) as a new isoscalar particle. A phase shift analysis shows a phase movement which is fully compatible with a resonance withJPC=2++. The most likely interpretation of the new resonance is a multiquark\((qq\overline {qq} or N\bar N)\) state.

Production of π+π−π0 in [formula omitted] annihilation at rest from atomic p-state

About 1.2·105 events of the pp-annihilation process at rest pp → π+π−π0 occuring in a H2 gas target at NTP have been analysed with special emphasis on the study of annihilation from atomic P-state. The branching ratio pp → π+π−π0/pp → all of 4.5 ± 0.5% is determined. Partial wave analysis shows strong ϱ(770) production from 1P1and3P1 and strong f2(1270) production from 3P1. P-wave and bubble chamber results concerning the S-wave are compared.

L ? emission from Ar++H2 collisions in the threshold energy region

In the energy range 2.4 to 33.3 eVCM, relative cross sections have been measured forLα emission from impact of Ar+ ions in a beam on a H2 gas target. Absolute cross sections, obtained by normalization to literature data, are 1–10×10−16cm2 for metastable Ar+ and 1–20×10−18cm2 for ground state Ar+. In the former case, the dominant mechanism is probably dissociative electronic energy transfer, while in the latter case dissociative charge transfer is the most likely process. In addition, at the lowest energiesLα resulting from a chemiluminescent rearrangement Ar++H2→ArH++H(2p) has been observed.