Measurement Of Inelastic Cross Section Research Articles

Neutron Inelastic Cross Section Measurements for Sodium

Inelastic scattering cross sections for sodium are of interest to the development of sodium cooled fast reactors. A recent OECD-NEA subgroup analysed the sensitivity of reactor parameters to cross sections and accordingly determined target uncertainties for the nuclear data. Comparing these target uncertainties with the current status of nuclear data uncertainties and covariance data resulted in a list of target priorities. Among these features sodium inelastic scattering for which a target uncertainty of about 5% was established, approximately two to three times as good as the uncertainty for current evaluated data files for this isotope (see OECD-NEA High Priority Request List, http://www.nea.fr/html/dbdata/hprl/hprlview.pl?ID=448). At IRMM, the GAINS gammaarray for inelastic neutron scattering was developed with the purpose of measuring cross sections with uncertainties at or below the target uncertainties for nuclides like Na using the (n, n′γ)technique. Measurements were performed at the GELINA facility at a 200 m flight path with eight high purity germanium detectors. The sample was an 80 mm diameter metallic disk prepared at IRMM by cutting, pressing, rolling and punching. For the experimental work, a careful review was made of the gamma-efficiency calibrations and the flux normalization in order to investigate in detail the corrections and the final uncertainties that may realistically be achieved. An elaborate account will be presented of the data analysis and checks that have been made and implications for earlier work by our group will be discussed. First results will be shown for the gamma-production cross sections of the main transitions in the energy range from threshold to 10 MeV.

Measurement of inelastic cross sections for low-energy electron scattering from DNA bases

Purpose: To determine experimentally the absolute cross sections (CS) to deposit various amount of energies into DNA bases by low-energy electron (LEE) impact.Materials and methods: Electron energy loss (EEL) spectra of DNA bases were recorded for different LEE impact energies on the molecules deposited at very low coverage on an inert argon (Ar) substrate. Following their normalisation to the effective incident electron current and molecular surface number density, the EEL spectra were then fitted with multiple Gaussian functions in order to delimit the various excitation energy regions. The CS to excite a molecule into its various excitation modes were finally obtained from computing the area under the corresponding Gaussians.Results: The EEL spectra and absolute CS for the electronic excitations of pyrimidine and the DNA bases thymine, adenine, and cytosine by electron impacts below 18 eV were reported for the molecules deposited at about monolayer coverage on a solid Ar substrate.Conclusions: The CS for electronic excitations of DNA bases by LEE impact were found to lie within the 10216 to 10218 cm2 range. The large value of the total ionisation CS indicated that ionisation of DNA bases by LEE is an important dissipative process via which ionising radiation degrades and is absorbed in DNA.

Erratum: Measurements of inelastic cross sections in relativistic deuteron-on-lead reactions [Phys. Rev. C82, 044605 (2010)

Erratum: Measurements of inelastic cross sections in relativistic deuteron-on-lead reactions [Phys. Rev. C<b>82</b>, 044605 (2010)

Measurement of inelastic cross sections in relativistic deuteron-on-lead reactions

The inelastic cross section of deuterons hitting a lead target has been determined by the beam attenuation technique. A spallation neutron source based on a lead target was irradiated with 1.6- and 2.5-GeV deuterons. Solid-state nuclear track detectors as well as the activation method were used to obtain the neutron and proton distribution along the surface of the source. The attenuation coefficient was estimated by fitting the experimental data and taking into account the buildup effect and the beam attenuation. Using the attenuation coefficient, the interaction length and then the inelastic cross section of deuterons on lead reaction were determined.

Empirical fit to precision inclusive electron-proton cross sections in the resonance region

An empirical fit is described to measurements of inclusive inelastic electron-proton cross sections in the kinematic range of four-momentum transfer $0\ensuremath{\leqslant}{Q}^{2}&lt;8$ GeV${}^{2}$ and final-state invariant mass $1.1&lt;W&lt;3.1$ GeV. The fit is constrained by the recent high-precision longitudinal and transverse separated cross section measurements from Jefferson Lab Hall C, unseparated Hall C measurements up to ${Q}^{2}$ $\ensuremath{\approx}7.5$ ${\mathrm{GeV}}^{2}$, and photoproduction data at ${Q}^{2}=0$. Compared to previous fits, the present fit covers a wider kinematic range, fits both transverse and longitudinal cross sections, and features smooth transitions to the photoproduction data at ${Q}^{2}=0$ and deep inelastic scattering data at high ${Q}^{2}$ and $W$.

Indirect measurement of inelastic cross section of relativistic protons in Pb target

The inelastic cross section of relativistic protons in Pb was determined indirectly by measuring the neutron distribution along a Lead spallation neutron source. The spallation neutron source was irradiated by 1, 1.5 and 2 GeV protons. The experimental results were obtained using passive methods. By the use of the beam attenuation coefficient, deduced by a fitting procedure of experimental data, the inelastic cross section of protons in Pb was determined.

Empirical fit to inelastic electron-deuteron and electron-neutron resonance region transverse cross sections

An empirical fit is described to measurements of inclusive inelastic electron-deuteron cross sections in the kinematic range of four-momentum transfer $$0 \le Q^2<10$$ GeV$^2$ and final state invariant mass $1.2<3$ GeV. The deuteron fit relies on a fit of the ratio $R_p$ of longitudinal to transverse cross sections for the proton, and the assumption $R_p=R_n$. The underlying fit parameters describe the average cross section for proton and neutron, with a plane-wave impulse approximation (PWIA) used to fit to the deuteron data. Pseudo-data from MAID 2007 were used to constrain the average nucleon cross sections for $W<1.2$ GeV. The mean deviation of data from the fit is 3\%, with less than 5\% of the data points deviating from the fit by more than 10\%.

Deeply virtual compton scattering in color dipole formalism

In this contribution we summarize recent investigations on the deeply virtual Compton Scattering (DVCS) within the color dipole approach. The color dipole cross section is implemented through the phenomenological saturation model. The role played by its QCD evolution and skewedness effects in the DVCS cross section are discussed. The results are compared with the recent H1 and ZEUS Collaborations data. The skewing factor, defined as the ratio of the imaginary parts of the amplitudes ImA(g*p ® g* p)/ImA(g*p ® gp) can be extracted from the data using recent DVCS and the inclusive inelastic cross section measurements at DESY-HERA. We report on this experimental extraction and compare the results to the theoretical predictions for NLO QCD and the color dipole approach.

An extraction of the skewing factor from DESY-HERA data

In this contribution we present recent investigation on the extraction of the skewing factor, defined as the ratio of the imaginary parts of the amplitudes Im ${\cal A}$(gamma* p <FONT FACE=Symbol>® g</FONT>* p)/ Im ${\cal A}$(gamma* p <FONT FACE=Symbol>® g</FONT> p). This factor is extracted from the data using the recent DVCS and the inclusive inelastic cross section measurements at DESY-HERA. We compare the results to the theoretical predictions for NLO QCD and the color dipole approach.

Measurements of total and inelastic cross sections in positron-Cs and electron-Cs collisions

Measurements of total and inelastic cross sections in positron-Cs and electron-Cs collisions

Differential cross sections for collisions of hexapole state-selected NO with He

The first measurements of differential inelastic collision cross sections of fully state-selected NO (j=12, Omega=12, epsilon= -1) with He are presented. Full state selection is achieved by a 2 m long hexapole, which allows for a systematic study of the effect of parity conservation and breaking on the differential cross section. The collisionally excited NO molecules are detected using a resonant (1+1') REMPI ionization scheme in combination with the velocity-mapped, ion-imaging technique. The current experimental configuration minimizes the contribution of noncolliding NO molecules in other rotational states j, Omega, epsilon--that contaminates images--and allows for study of the collision process at an unprecedented level of detail. A simple method to correct ion images for collision-induced alignment is presented as well and its performance is demonstrated. The present results show a significant difference between differential cross sections for scattering into the upper and lower component of the Lambda-doublet of NO. This result cannot be due to the energy splitting between these components.

Magnetic control of the interaction in ultracold K-Rb mixtures.

We predict the presence of several magnetic Feshbach resonances in selected Zeeman sublevels of the isotopic pairs 40K-87Rb and 41K-87Rb at magnetic fields up to 10(3) G. Positions and widths are determined combining a new measurement of the 40K-87Rb inelastic cross section with recent experimental results on both isotopes. The possibility of driving a K-Rb mixture from the weak to the strong interacting regime tuning the applied field should allow one to achieve the optimal conditions for boson-induced Cooper pairing in a multicomponent 40K-87Rb atomic gas and for the production of ultracold polar molecules.

Measurement of absolute differential cross sections for the excitation of the n = 2 states of helium at and

A novel scheme for the measurement of inelastic differential cross sections (DCS) at is presented. It uses a magnetically collimated electron-impact spectrometer where the backward-scattered electrons are reflected into the forward direction by a potential barrier, and enter the energy analyser located at . Pulsed incident electron beam and time-of-flight detection are used to differentiate the backward- and forward-scattered electrons. The instrument yields the ratio of the forward and backward DCS. This data is then normalized to the absolute DCS at , measured with an instrument using electrostatic hemispherical analysers, to yield absolute DCS at . The combined results from both instruments are absolute DCSs as a function of scattering angle continuously from to plus one more data point at . Absolute DCS is also obtained as a function of incident energy at and at . The technique is applied to measure the DCSs for the excitation of the four n = 2 states of helium as a function of scattering angle at 22, 25, and 29.6 eV, and as a function of energy from threshold to 28 eV at and . The results are compared with recent calculations.

The H2–Ne interaction

New measurements of the elastic and rotationally inelastic differential cross sections for the Ne–D2, Ne–H2 system are compared with exact and approximate quantum calculations. The three most recent high quality, semiempirical interaction potentials available in the literature for the Ne–H2 system yield consistent theoretical scattering cross sections for Ne–H2 and for Ne–D2. They also agree with previous and with present inelastic cross section measurements for D2. However, the theory underestimates by 30% the newly measured rotational excitation in Ne–H2 collisions discussed here. We therefore propose a new potential with a modified repulsive barrier that succeeds in describing both Ne–D2 and Ne–H2 rotationally inelastic scattering experiments for j=0→j′=2 within an accuracy of a few percent.

Inelastic transverse electron scattering on 25Mg.

Measurements of inelastic electron cross sections from {sup 25}Mg at a backward angle and in the energy range 120 to 260 MeV are analyzed, and transverse form-factors results for the two lowest excited levels of the fundamental band were extracted. This new information is compared with rotational model calculations, in which the collective current contributions are included in phenomenological ways and on more microscopic theoretical grounds. For the energy levels considered the overall agreement is good, although no clear distinction between the various approximations for the rotational current could be made with the presently available data.

Elastic and inelastic scattering of nucleons from 16O

Measurements of differential elastic and inelastic cross sections for neutron scattering from 16O at incident energies 18 to 26 MeV are presented. In addition to cross sections for neutron scattering differential cross sections for proton scattering up to 66 MeV are described in terms of phenomenological optical model potentials. At 24.5 MeV incident energy inelastic scattering up to 11.5 MeV excitation was measured. The elastic and inelastic compound nucleus contributions were examined. Direct inelastic scattering from the normal parity states was calculated using the DWBA and coupled-channel formalisms. The inelastic scattering cross section from non-normal parity state 2 − was calculated using the coupled-channel formalism via multi-step processes. Cross sections due to inelastic scattering from some of the states, which are thought to be members of an excited state rotational band were calculated using both vibrational and rotational approaches and were compared.

Improved potential energy surfaces for the interaction of H2 with Ar, Kr, and Xe

A combined analysis of discrete infrared and microwave spectra, elastic and inelastic differential cross section measurements, and virial coefficient data has been used to determine improved potential energy surfaces for the H2–Ar, –Kr, and –Xe systems. Key improvements over previous surfaces for these species are an improved delineation of the diatom bond length dependence of the potential anisotropy, and the first experimental determination of a distinct P4(cos θ) anisotropy for an atom–diatom system. The effective anisotropy strength seen by bound state properties (such as transition frequencies) is found to increase from H2–Ar to H2–Kr to H2–Xe, although that seen by properties sensitive to the short-range potential (such as rotational predissociation and rotational inelasticity) decreases along this series. This reflects the lack of conformality of the various potentials; however, both these and analogous trends predicted for properties such as vibrational frequency shifts and vibrational inelasticity are readily understood in terms of the detailed properties of these surfaces.

Measurement of Nuclear Inelastic Scattering Cross Section of Thorium-232 for 144keV Si-Filtered Neutrons

The nuclear inelastic scattering cross section of 232Th has been measured at 144 keV using a Si-filtered neutron beam from the University of Missouri Research Reactor (MURR). The energy spectrum of the scattered neutrons was measured with a spherical hydrogen-gas counter and a pulse-height-unfolding procedure. Data were taken at nine scattering angles from 30° to 150° in 15° increments. The results provide new experimental information below 250 keV. The angle-integrated cross section is 0.74±0.05 barn, which agrees with the evaluation JENDL-2 and with a coupled-channel calculation where the inelastic scattering through the direct-excitation process of the collective rotational motion of a deformed nucleus is included as well as that through the compound-nucleus-formation process. Experimental results have been obtained also for the angular dependence of the elastically scattered neutrons at 144 keV.

Os-187(n, n') inelastic cross section at 34 keV

view Abstract Citations (19) References (7) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Os-187(n, n') inelastic cross section at 34 keV Macklin, R. L. ; Hill, N. W. ; Harvey, J. A. ; Winters, R. R. Abstract A measurement of the Os-187 inelastic neutron cross section to the 3/2(-) 9.75 keV excited state with 34 + or - 2 keV incident neutrons gives 1.5 + or - 0.2 barns. Pulsed neutron time of flight and a short anisotropic iron-aluminum filter allowed separation of the inelastic yield from the 1/2(-) ground-state elastic yield at 24 keV. The influence of the result on r-process galactic age calculations via the Re-Os decay chronometer is discussed, and the need for further theoretical calculations is emphasized. Publication: The Astrophysical Journal Pub Date: November 1983 DOI: 10.1086/161456 Bibcode: 1983ApJ...274..408M Keywords: Galactic Evolution; Neutron Cross Sections; Nuclear Reactions; Osmium Isotopes; Cosmology; Neutron Beams; Radioactive Decay; Rhenium Isotopes; Astrophysics full text sources ADS |

Pressure broadening of CO infrared lines perturbed by H2 and He

We present results of infrared linewidth measurements at low and room temperatures for CO diluted in H2 and He using a tunable diode laser in the 4.7 μm spectral region (CO fundamental band). Information on the intermolecular potential is obtained by comparison with results of dynamical calculations. In the case of CO–H2 pressure broadening (PB), data are compared to direct measurements of inelastic cross sections by infrared–infrared double resonance and to ab initio quantum calculations. In the case of CO–He, experimental PB coefficients are compared to theoretical cross sections derived from two ab initio potential energy surfaces.