Preliminary Cross Section Research Articles

Measurements of the Neutron Capture Cross Section of Am-243 with the ANNRI beamline, MLF/J-PARC

The neutron capture cross section of 243Am from thermal to 100 keV was measured using the Accurate Neutron-Nucleus Reaction Measurement Instrument (ANNRI) at the Japan Proton Accelerator Research Complex (J-PARC). The time-of-flight (TOF) method using a NaI(Tl) detector was employed in these measurements and the pulse-height weighting technique was used to derive the neutron capture yield. The preliminary cross section was determined by normalizing the results to JENDL-4.0 cross section data at the third resonance of 243Am. In the thermal energy, the preliminary result is in good agreement with the two latest experimental data measured by the TOF and the activation methods but higher than the evaluated values in JENDL-5.

Neutron Capture Cross Section Measurement and Resonance Analysis of 107Pd Using ANNRI at MLF/J-PARC

The neutron capture cross sections of 107Pd were measured using the Accurate Neutron-Nucleus Reaction Measurement Instrument (ANNRI) at the Japan Proton Accelerator Research Complex (J-PARC). Capture γ-rays were detected with a NaI(Tl) spectrometer. The incident neutron energy was determined by the time-of-flight method. The preliminary cross section was derived from thermal to resonance energy region. In the resonance region, resonance parameters were derived by resonance analysis using REFIT code. The resonance parameter was close to the value of JENDL-4.0.

Cross section measurements of low-energy charged particle induced reactions using moderated neutron counter arrays

A high-and-flat efficiency moderated neutron detection array of 3He counters has been recently developed for photoneutron cross section measurements at the future ELI-NP gamma-ray beam source. We have designed a three rings geometry of 31 counters with a ˜37% efficiency flat within 5% in the 10 keV to 5 MeV neutron energy interval. A commissioning experiment was performed using proton beams delivered by the 9 MV Tandem accelerator of IFIN-HH. We measured the neutron production cross sections for proton induced reactions on nat Cu and 27Al. The (p, xn) reactions on nat Cu were investigated in the 4.5 MeV to 14 MeV proton energy range with 250 keV steps, using pulsed and continuous proton beams. The low energy measurements below 10 MeV served to validate the detection efficiency calibration against well-known natCu(p, n) cross sections. The 27Al(p, n) reaction was investigated in the 5.8 MeV to 6.75 MeV energy range with 5 keV steps. Preliminary cross section results are here compared with preceding data.

The Forward-Plane Star in ^1H(d, pp)n Breakup at E_{{{varvec{d}}}}=mathbf{80}\xa0MeV/nucleon

Analysis of the data acquired with the BINA detector system in ^1H(d, pp)n reaction at the beam energy of 80 MeV/nucleon makes a systematic analysis of the star configurations possible. This paper shows the preliminary cross section of the Forward-Plane Star (FPS) configuration with the neighbouring configurations.

Current stage of studies of the star configurations at intermediate energies with the use of the BINA detector

The~Space Star Anomaly in proton-deuteron breakup cross-section occurs at energies of about 10~MeV. Data for higher energies are sparse. Therefore, a~systematic scan over star configurations in the~range of intermediate energies between 50 and 100 MeV/nucleon is carried out on the~basis of data collected with the~large acceptance BINA detector. The~preliminary cross section results for forward star configurations at 80 MeV/nucleon slightly surpass the~theoretical calculations, but the~systematic uncertainties are still under study. Also, a~new variable describing rotation of star configurations is proposed.

The Neutron Facility at NCSR "Demokritos"- Implementation in the Case of the 232Th(n,2n) and 241Am(n,2n) Reactions

In the 5.5 MV tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" monoenergetic neutron beams can be produced in the energy ranges 120-650 keV, 4-11.5 MeV and 16-20.5 MeV by using the 7Li(p,n), 2H(d,n) and 3H(d,n) reactions, respectively. The corresponding beam energies and ions delivered by the accelerator, are 1.92-2.37 MeV protons, 0.8-9.6 MeV deuterons and 0.8-3.7 MeV deuterons, for the three reactions, respectively. Experimental results for neutron energies from threshold up to 11.5 MeV and at 17.1 MeV will be given for the 232Th(n,2n)231Th reaction, while for the 241 Am(n,2n)240 Am reaction, preliminary cross section data at 10.4, 10.6 and 17.1 MeV will be discussed. In the framework of the CERN n-TOF collaboration, the cross section of these reactions have been measured relative to the 197Au(n,2n)196Au, 27Al(n,a)24Na and 93Nb(n,2n) reaction cross sections, by using the activation method. In addition to the experimental work, theoretical Statistical model calculations are being carried out using the computer code STAPRE/F. The results are compared to the experimental data.

K0SΣ0 photoproduction at the BGO-OD experiment

The BGO-OD experiment at the ELSA accelerator facility uses an energy tagged bremsstrahlung photon beam to investigate the excitation structure of the nucleon via meson photoproduction. The setup with a BGO calorimeter surrounding the target and an open dipole spectrometer covering the for ward region is ideally suited for investigating low momentum transfer processes, in particular in strangeness photoproduction. The associated photoproduction of K0S and hyperons is essential to understand the role of K* exchange mech anisms. A cusp-like structure observed in the yp → K0SΣ+ reaction at the K* threshold is described by models including dynamically generated resonances from vector meson-baryon interactions. Such interactions are pre dicted to give a peak like structure in K0SΣ0 photoproduction off the neutron. A very preliminary cross section is determined and compared to the prediction, the results appear to support the model

Neutron capture and total cross-section measurements of 155Gd and 157Gd at ANNRI in J-PARC

Neutron capture and total cross sections of 155Gd and 157Gd were measured with the neutron time-of-flight method in Accurate Neutron-Nucleus Reaction measurement Instrument at Material and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex using the NaI (Tl) spectrometer and Li-glass detectors. Preliminary cross sections were obtained in the neutron energy region from 4 meV to 100 meV. The derived cross sections agree with evaluated values in JENDL 4.0 and the experimental results by Mastromarco but were not consistent with those by Leinweber.

Neutron inelastic cross section measurements on 58,60Ni

A natural nickel sample was used at the GELINA (Geel Electron LINear Accelerator) neutron source of the European Commission, Joint Research Centre, Geel to measure the neutron inelastic cross sections. The GAINS (Gamma Array for Inelastic Neutron Scattering) spectrometer was employed to detect the emitted γ rays while a 235U fission chamber monitored the neutron flux. We report the preliminary production cross sections corresponding to the first transitions in 58,60Ni in comparison with previously reported data and with TALYS 1.9 calculations performed using the default input parameters.

Recent results of charged pion and kaon photoproduction on the proton at SPring-8/LEPS

We carry out photoproduction experiments by using linearly polarized photon beams with energies of 1.5-3 GeV at SPring-8/LEPS. One of our physics motivations is to understand reaction mechanisms of hadron photoproduction. We study (1) y→p→ π-Δ++, (2) y→p→ π+n, (3) y→p→ K+Λ(K+Σ0), and (4) y→p→ π+Δ0 reactions which produce (1) uu, (2) dd, (3) ss, and (4) dd quark-antiquark pairs in the final state. Differential cross sections and photon beam asymmetries have been measured at forward meson angles of 0.6 < cos θcm <1. Precise comparison between the π-Δ++ and π+Δ0 reactions plays an important role in the study of nucleon resonances. It enables to distinguish between N* and Δ* by taking the cross section ratios of the two reactions. We have measured preliminary cross section ratios dσ(π+Δ0)/dσ(π-Δ++). The ratios are found to be close to 1/3, which is expected from the exchange of isospin=1 in the t channel, for 0.966< cos θcm <1 and all the photon energies. The ratios become larger than 1/3 and close to 1 for larger angles and higher energy regions. The larger ratios might be due to A resonances, giving the ratio 4/3, excited in the intermediate state

Four-body treatment of the antihydrogen-positronium system: binding, structure, resonant states and collisions

We have developed a coupled-rearrangement-channel method allowing the rigorous non-adiabatic treatment of the multi-channel scattering problem for four particles. We present the study of the binding, resonant and collisional properties of the bar {H}-Ps system with the total angular momentum J = 0+ (singlet positronic configuration). The binding energy, the life-times of the resonant states and the collisional cross sections are calculated and discussed. We present the preliminary cross sections for the elastic and inelastic bar {H}-Ps scattering, notably for the excitation of Ps and for the rearrangement reaction producing the bar {H}^{+} ions.

Photoproduction of $${\varvec{\pi }}^{{\varvec{-}}}{\varvec{\varDelta }}^{{\varvec{++}}}$$ π - Δ + + , $${\varvec{\pi }}^{{\varvec{+}}}{\varvec{\varDelta }}^\mathbf{0 }$$ π + Δ 0 , and $${\varvec{\pi }}^{{\varvec{+}}}{} \mathbf{n}$$ π + n on the Proton at $${\varvec{E}}_{{\varvec{\gamma }}}=\mathbf{1.5}$$ E γ = 1.5 –3.0 GeV

We carry out photoproduction experiments by using linearly polarized photon beams with energies of 1.5–3.0 GeV at SPring-8/LEPS. There is no distinct peak structure due to nucleon or $$\varDelta $$ resonances in the preliminary cross sections for the $$\gamma p$$ $$\rightarrow $$ $$\pi ^{-}\varDelta ^{++}$$ , $$\pi ^{+}\varDelta ^{0}$$ , and $$\pi ^{+}n$$ reactions for 0.7 $$<\cos \theta _{\pi }<$$ 1. The cross section ratios $$\sigma $$ ( $$\pi ^{+}\varDelta ^{0}$$ )/ $$\sigma $$ ( $$\pi ^{-}\varDelta ^{++}$$ ) are close to 1/3, which is expected from the isospin = 1 exchange in the t-channel, at small $$\pi $$ angles and become larger than 1/3 at large $$\pi $$ angles. The photon beam asymmetries are small negative values, small positive values, and large positive values for the $$\pi ^{-}\varDelta ^{++}$$ , $$\pi ^{+}\varDelta ^{0}$$ , and $$\pi ^{+}n$$ reactions, respectively. The asymmetries are sensitive to reaction mechanisms and are found to be largely different among these reactions. The asymmetries are strong constraint in theoretical studies and expected to play an important role in searching for new nucleon resonances.

STORY OF A BERM TYPE REVETMENTORDU GIRESUN AIRPORTTHE FIRST SEA FILL AIRPORT OF TURKEY

Ordu Giresun Airport is the first airport of Turkey that is completely built on a sea fill area situated at the Black sea coast of Turkey and at equal distances to Ordu and Giresun cities. The reclamation covers 1.6 million m2 area that is surrounded with a total of 8.6 km revetment. The longest part of the revetment which is in parallel with the shoreline and at the offshore side of the reclamation area, is planned as a berm type revetment. In this sense, the preliminary cross section provided at the tender stage is checked, modifications are performed considering several criteria such as economics, performance, availability of rocks, etc. In addition to the design stages, several cross sections together with the suggested modifications are checked with laboratory tests. This paper covers the design stages where this criteria is taken into account, laboratory tests and the performance of the cross section during construction stages.

Electromagnetic Scattering of Electrically Large Ship above Sea Surface with SBR-SDFM Method

Hybrid scheme combining shooting and bouncing ray with semi-deterministic facet model is proposed to analyze composite scattering from ship-ocean scene in this study. This model can deal with complex electromagnetic interaction between ship and sea surface. Thus, scattering properties of composite ship-ocean scenes with influence of various parameters (such as incident angle and wind speed) can be studied and analyzed efficiently. Studying such properties is of significance for target detection and high-resolution radar imaging in sea environments. Accuracy and performance of this method are validated and evaluated by comparing with multilevel fast multipole method of FEKO for electrically small objects. All simulation results indicate that the proposed method is suitable for providing preliminary radar cross section prediction of electrically large composite model.

Impact of the $$\gamma _{\nu }$$NN* Electrocoupling Parameters at High Photon Virtualities and Preliminary Cross Sections off the Neutron

Meson-photoproduction measurements and their reaction-amplitude analyses can establish more sensitively, and in some cases in an almost model-independent way, nucleon excitations and non-resonant reaction amplitudes. However, to investigate the strong interaction from already explored—where meson-cloud degrees of freedom contribute substantially to the baryon structure—to still unexplored distance scales—where quark degrees of freedom dominate and the transition from dressed to current quarks occurs—we depend on experiments that allow us to measure observables that are probing this evolving non-perturbative QCD regime over its full range. Elastic and transition form factors are uniquely suited to trace this evolution by measuring elastic electron scattering and exclusive single-meson and double-pion electroproduction cross sections off the nucleon. These exclusive measurements will be extended to higher momentum transfers with the energy-upgraded CEBAF beam at JLab to study the quark degrees of freedom, where their strong interaction is responsible for the ground and excited nucleon state formations. After establishing unprecedented high-precision data, the imminent next challenge is a high-quality analysis to extract these relevant electrocoupling parameters for various resonances that can then be compared to state-of-the-art models and QCD-based calculations. The vast majority of the available exclusive electroproduction cross sections are off the proton. Hence flavor-dependent analyses of excited light-quark baryons are lacking experimental data off the neutron. The goal is to close this gap by providing exclusive \({\gamma }_{\nu }(n) \rightarrow p^{+} {\pi }^{-}\) reaction cross section off deuterium and to establish a kinematical final-state-interaction (FSI) correction factor (R) map that can be determined from the data set itself. The “e1e” Jefferson Lab CLAS data set, that is analyzed, includes both a hydrogen and deuterium target run period, which allows a combined analysis of the pion electroproduction off the free proton, the bound proton, and the bound neutron under the same experimental conditions. Hence it will provide the experimentally best possible information on the off-shell and FSI effects in deuterium, which must be considered in order to extract the information off the neutron. The cross section analysis of this data set, that is currently underway, will considerably improve our knowledge of the \(Q^{2}\) evolution of resonance states off bound protons and neutrons. Recent results presented here and in these proceedings are demonstrating the status and continuous progress of data analyses and their theoretical descriptions, as well as highlighting the experimental and theoretical outlook of what shall and may be achieved in the new era of the 12-GeV upgraded transition form factor program.

Neutron Capture Cross Section of 239Pu

The Detector for Advanced Neutron Capture Experiments (DANCE) has been used to measure the 239Pu(n,γ) cross section from 10 eV to the keV region. Three experimental run conditions were used to characterize the prompt fission γ-ray spectrum across the entire energy regime, measure the cross section in the resolved resonance region, and obtain necessary count rate well into the keV region. The preliminary cross sections are in good agreement with current evaluations from 10 eV to 80 keV.

Study of the $^{15}$O$(2p,\gamma )^{17}$Ne Cross Section by Coulomb Dissociation of $^{17}$Ne for the $rp$ Process of Nucleosynthesis

The O-15(2p, gamma)Ne-17 cross section has been studied by the inverse reaction, the Coulomb dissociation of Ne-17. The experiment has been performed at the GSI. The Ne-17 excitation energy prior to decay has been reconstructed by using the invariant-mass method. The preliminary differential and integral Coulomb dissociation cross sections (sigma(Coul)) have been extracted, which provide a photoabsorption (sigma(photo)) and a radiative capture cross section (sigma(cap)). Additionally, important information about the Ne-17 nuclear structure will be obtained. The analysis is in progress.

EXCLUSIVE MEASUREMENTS OF OMEGA ELECTROPRODUCTION OFF THE PROTON IN THE RESONANCE REGION

A complete theory of strong interactions must describe the excited baryon spectrum as well as the structure of prominent states, which reflects the dynamics of nonperturbative QCD. Beyond the discriminating power of exclusive single- and double-pion electroproduction, the ω channel provides an additional probe of high-mass excited states. The current analysis provides preliminary differential and integrated cross sections of ω electroproduction off the proton from W = 1.7 to 3.2 GeV and Q2 = 1.5 to 5.5 GeV2. The data was collected by JLab's CLAS detector during two run periods and comprises the largest sample of exclusive resonance-region ω electroproduction ever analyzed. Preliminary Legendre decomposition of the cross sections supports previous indications of s-channel contributions to cross sections in the resonance region.

Investigations of the charge symmetry breaking reactiondd→απ0with the WASA-at-COSY experiment

The charge symmetry breaking reaction dd → 4 Heπ0 has been measured with the WASA-at-COSY experimental setup at a beam momentum of pd = 1.2 GeV/c (Q = 60 MeV). For the first time a signal for this reaction has been observed at an excess energy well above threshold. The determined preliminary total cross section is σ tot prel = (120±20stat. ) pb.

Electroproduction of K+ Λ at JLab Hall-C

A Λ hypernuclear spectroscopic experiment, JLab E05-115 was performed at JLab Hall-C in 2009 by the (e, e′K+) reaction. Data of Λ hypernuclei with mass numbers from A = 7 to A = 52 were successfully taken, and the analyses are in progress. A polyethylene (CH2) target was used as a proton target to calibrate energy scales, and to study elementary process of the p(e, e′K+)Λ, Σ0 reaction. A preliminary differential cross section of K+Λ electro-production at low Q2 [~0.01 (GeV/c)2] and at small kaon angles \({({\rm cos} \theta_{\rm K}^{\rm CM} \sim 0.97)}\) is reported in the present article.