Proton Angles Research Articles

Angle independence of the5Lig.s. Γ width

We measured the differential cross-sections for the6Li(3He, ααp) reaction at various detector angles in a kinematical complete way by 7 and 9 MeV energy3He beams. The analysis of the αp bidimensional spectra allowed us to separate the5Lig. s. contributions from the first excited state ones of the same nucleus. The Γ(5Lig. s.) values deduced from both the experiments atE(3He)=7 and 9 MeV do not appear to be dependent on the: i)5Lig. s. emission angle, ii)5Lig. s. decay proton angle when correlated to the various α-particle emission angles.

Coplanar and noncoplanar pp bremsstrahlung.

The Harvard noncoplanar geometry is used to specify calculations of the different and integrated cross sections and of the component analyzing powers from [ital pp] bremsstrahlung. This geometry is equivalent to spherical polar coordinates for coplanar scattering. A wide range of incident energies and symmetric proton emission angles are considered in studying various properties of the reaction. Emphasis is placed on an energy of 280 MeV and for forward proton angles, at which results are most sensitive to specific off-of-the-energy-shell properties of the two nucleon [ital t] matrices. Those [ital t] matrices are generated with various interactions. The importance of the [ital NN] [ital t]-matrix off-diagonal tensor contributions for the coplanar observables as demonstrated in the pioneering work of Brown is clearly shown. Photon cross sections vary with the noncoplanarity of the reaction due in part to changes in relative importance of diverse [ital NN] channel [ital t] matrices. The analyzing powers likewise vary with azimuthal angle and reveal a particular sensitivity to the tensor coupled [sup 3][ital P][sub 2-][sup 3][ital F][sub 2] channels and to the [sup 3][ital P][sub 0] channel.

Application of CR-39 Track Detector to Neutron Spectrum Measurement.

A new technique for estimating the neutron energy spectrum with CR-39 track detectors has been proposed for application to a singly pulsed neutron field where prevailing counters cannot operate properly. The CR-39 sample exposed to neutrons was intermittently etched, then the major and minor radii of respective etch pits were measured for each etching stage and the growth curve was obtained. The analysis method of growth curves was also designed, with which both the energy and the angle of recoil protons could be evaluated and converted into the energy of neutrons incident normally. The neutron irradiation experiments were carried out with the 46 MeV electron linear accelerator at the Research Reactor Institute, Kyoto University. It was confirmed from comparing with the reference spectrum measured by the neutron time-of-flight method that the present growth-curve method is useful for the estimation of the neutron energy distribution between about 0.3 and 2 MeV. Moreover, we have experimentally examined th...

Fast neutron dosimetry with CR-39 using electrochemical etching

A Monte Carlo method is used in order to calculate the response (tracks⋯cm −2 ⋯ μSv −1 ) of a fast neutron dosemeter, composed of a polyethylene radiator and CR-39 plastic track detector, to monoenergetic neutron beams at normal incidence and taking into account the electrochemical etching conditions. The method is applied to neutrons having energies in the range 0.08–10 MeV. The total number of protons emerging from the radiator is calculated, as well as their energetic and angular distribution. Detection efficiency as a function of proton energy and angle is taken into account. The theoretical calculation is compared with experimental results obtained for Am-Li and Pu-Be sources for protonic equilibrium radiator thicknesses

Structure of 4Li and 4He observed in the 1H( alpha,3He p)n reaction.

Kinematically complete measurements of the $^{1}\mathrm{H}$(\ensuremath{\alpha}${,}^{3}$He p)n reaction at ${\mathit{E}}_{\mathrm{\ensuremath{\alpha}}}$=170 MeV were made at several $^{3}\mathrm{He}$ and proton angles. Assuming an incoherent sum of different multipole contributions in different reaction channels, it was possible to describe all measured spectra consistently, taking into account sequential decay of states in $^{4}\mathrm{He}$ and $^{4}\mathrm{Li}$ and the p-n final state interaction. The parameters used to describe the p-n final state interaction and excited states in $^{4}\mathrm{He}$ are consistent with previous measurements. Resonance energies and widths for the ground state and the first excited state of $^{4}\mathrm{Li}$ were extracted which are considerably lower than assumed so far. The measured cross sections are in agreement with distorted-wave Born approximation calculations using folding form factors.

Measurement of inclusive 12C(e,p) cross sections.

We present data on inclusive ({ital e},{ital p}) scattering for electron beam energies of 460, 505, 647, 686, 698, and 800 MeV. Proton momentum spectra were obtained at fixed proton angles and for momenta from 300--1000 MeV/{ital c}. The data are compared to a popular parametrization that includes quasifree knockout, a quasideuteron mechanism, and pion production through the {Delta}.

Bremsstrahlung study of nuclear reaction dynamics: The 12C+p reaction

The energy dependence of the lifetime of the 12C(p, p) nuclear reaction in the excitation region of the overlapping resonance states 3.511 MeV, 3 − 2 and 3.547 MeV, 5 + 2 of the 13N compound nucleus is determined using the bremsstrahlung method. The influence of interference of the resonance states at the scattering angle of protons Θ f = 160° on the nuclear lifetime is studied. It is shown that the nuclear lifetime depends essentially on the scattering angle of the particle under simultaneous excitation of states with differing spins and parities.

(p,p alpha ) cluster-knockout reaction on 9Be at 200 MeV.

The ({ital p},{ital p}{alpha}) cluster-knockout reaction on {sup 9}Be has been investigated experimentally at a bombarding energy of 200 MeV. Coincident data were obtained at five quasifree angle pairs for proton angles ranging from 40{degree} to 80{degree}. The data were analyzed in terms of the distorted-wave impulse approximation. The calculated energy-sharing distributions reproduce the data reasonably well, indicating that the quasifree-knockout mechanism dominates the reaction. The factorization approximation employed in the calculation is found to be valid. The absolute spectroscopic factors derived from the data are in excellent agreement with lower-energy results, and compare well with shell-model predictions.

Neutron Dosimetry with CR-39 Track Detectors using Electrochemical Etching: Recent Improvements, Dosimetric Characteristics and Aspects of Routine Application

Recent progress in improving the dosimetric properties of CR-39 etched track detectors is reviewed. With respect to the two-step electrochemical etching (ECE) technique the effects of electrical field strength and various radiator/absorber combinations on the neutron energy response were investigated in the energy range 144 keV to 14 MeV, showing agreement between experimental and theoretical results for the neutron response, if appropriate field strength dependent critical proton angles are used for calculation. Results of international intercomparison experiments show that with respect to energy response the ECE technique has already reached a certain level of optimisation. The energy response, angular dependence, response of CR-39 in contact with (n,a) radiators, dose range and lowest detectable dose are discussed. The results of long-term fading and changes in response and background are presented for commercial CR-39 materials manufactured by American Acrylics and Pershore Mouldings, which were stored over more than one year in air or nitrogen. The high scatter in response and background within the sheet and batch production, and thus the lowest detectable dose and the relatively small dose range, still limit the application of CR-39 in personnel monitoring.

THE MONTE-CARLO SIMULATION OF THE FLUORESCENCE ENHANCING EFFECT IN PIXE

With monte-carlo method, the primary and second X-ray fluorescence excited by proton in thick target were simulated, and the fluorescence enhancing factors were obtained.The various enhancing factors were calculated with different proton incident energies and angles, X-ray ejection angles, and elements and their weight percentage in samples. Besides, the results of PIXE basically agreed with standard composition of steel samples using the calculated enhancing factors.

Exclusive quasi-deuteron absorption of pions in 16O and 18O at 116 MeV.

The reaction /sup 16/O(..pi../sup +/,2p)/sup 14/N was measured at T/sub ..pi../ = 116 MeV with an excitation energy resolution between 1.6 and 2.5 MeV with one proton angle fixed at 50/sup 0/ and for a wide range of the second angle. Proton angular correlations, energy sharing distributions, and recoil momentum distributions for four strongly populated states are consistent with a model of pion absorption on quasi-deuteron pairs with angular momentum transfer to the recoil nucleus of L = 0 (3.9 MeV state), L = 2 (7.0 and 11.0 MeV states), or a mixture of L = 0 and L = 2 (ground state). Integration of the measured absorption cross section over angle and up to 20 MeV of excitation shows that 19 +- 4% of the total absorption cross section can be found in two-proton final states near quasifree kinematics, with substantial additional two-nucleon strength between 20 and roughly 50 MeV of excitation. With estimated corrections for final-state interactions, about half of the absorption cross section below 20 MeV excitation proceeds via the direct quasifree ..pi..pn..-->..pp process. Absorption leading to the T = 1 state at 2.3 MeV is <5% as strong as absorption to the T = 0 groundmore » state. The /sup 18/O(..pi../sup +/,2p)/sup 16/N reaction was measured under the same kinematic conditions. States of less than 0.4 MeV excitation, which correspond to absorption on nucleons in different shells, account for at least 6.1 +- 0.6% of the estimated two-nucleon absorption cross section below 20 MeV excitation; no unexpected suppression of cross-shell absorption was found.« less

Photodisintegration of 4He in the Delta region.

Photoemission of protons from /sup 4/He is measured at theta/sub p/ = 30/sup 0/, 60/sup 0/, 90/sup 0/, and 105/sup 0/ in the photon energy range between 187 and 427 MeV. From the analysis of the momentum spectrum of protons, the differential cross sections for the photodisintegration of quasifree two-nucleon systems in the /sup 4/He nucleus are deduced as a function of the proton angle and the incident photon energy. The obtained cross sections for /sup 4/He are larger than those for the deuteron photodisintegration by a factor of about 4.5 in the energy region of the present experiment.

Polarisation effects in the [formula omitted] reaction at 33MeV

Differential cross sections and analysing powers were measured for the 12C( 3He, pp) 13C reaction induced by a 33 MeV polarised 3He beam at many combinations of detection angles of the coincident protons in both coplanar and out-of-plane configurations. Data characterised by low relative proton energies were successfully described by the sequential breakup model while at higher relative energies other reaction mechanisms become important.

Precise 2H(p,2p)n data in the small recoil region

Differential cross sections for the 2H(p,2p)n reaction at 508 MeV have been measured in a coplanar geometry for the proton angles 41.4°–41.4° and 30.1°–53.75°, for neutron recoil momenta up to 55 MeV/ c. A missing strength of 6.6% relative to the PWIA is found, with an absolute uncertainty of (1.9–2.7)%. The agreement is better when rescattering and final state interaction are taken into account. The calculation results are also compared to large recoil data previously published.

Four-body calculation of the breakup reaction 3He(p,pd)1H.

The Alt, Grassberger, and Sandhas four-body theory has been used to calculate the differential cross sections for the kinematically complete breakup reaction $^{3}\mathrm{He}$(p,pd${)}^{1}$H at various proton energies and angles. The two-body input consists of Yamaguchi potentials without Coulomb corrections and the (3+1) and (2+2) amplitudes were expanded using the generalized unitary pole expansion. The resulting effective two-body equations have been solved in the first-order K-matrix approximation. Reasonable agreement with experiment was obtained.

Pi +d--> pi

The vector analyzing power, ${\mathrm{iT}}_{11}$, has been measured for the ${\ensuremath{\pi}}^{+}$d\ensuremath{\rightarrow}${\ensuremath{\pi}}^{+}$pn reaction in a kinematically complete experiment. The dependence of ${\mathrm{iT}}_{11}$ on the momentum of the proton has been obtained for 35 pion-proton angle pairs at pion bombarding energies of 180, 228, and 294 MeV. The data are compared with a relativistic Faddeev calculation. The theoretical prediction that there is a single universal shape for ${\mathrm{iT}}_{11}$, which is positive at low proton momenta and negative at large proton momenta, independent of the final pion and proton angles or of the incident pion energy is confirmed by the experiment.

A study of the reaction 2H( π±, p)X

We have studied the excitation function of the reaction 2H( π ±, p)X at a fixed proton angle of 90° for several fixed proton momenta of the detected proton as a function of the incident pion energy. No signal was found for a previous candidate for a dibaryon resonance around a mass of 2.23 GeV. The general trend of the data is reproduced by a multiple scattering theory

Very backward π0 and η0 production by proton projectiles on a deuterium target at intermediate energies

The production of π 0 and η 0 mesons in the reactions pd → π 0 τ and pd → η 0 τ has been studied at very backward angles for kinetic proton energies T p ranging from 0.92 to 2.6 GeV. The excitation functions at θ π = θ η = 180° display large structures which might be related to baryonic (Δ and N ∗) excitations in the intermediate state.

Direct detection of solanesol in tobacco by proton and carbon-13 magic angle spinning NMR

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDirect detection of solanesol in tobacco by proton and carbon-13 magic angle spinning NMRJan B. WootenCite this: J. Agric. Food Chem. 1985, 33, 3, 419–425Publication Date (Print):May 1, 1985Publication History Published online1 May 2002Published inissue 1 May 1985https://doi.org/10.1021/jf00063a024RIGHTS & PERMISSIONSArticle Views104Altmetric-Citations14LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (985 KB) Get e-Alerts Get e-Alerts

First measurements of i T11 in the pion-deuteron breakup reaction

The vector analysing power, i T 11, and differential cross section for the π + d→π + pn reaction at T π = 228 MeV were measured in a kinematically complete experiment, using a polarized deuteron target. Results are presented for a pion angle of 85° with six proton angles between 27° and 61°. A comparison is made with theoretical calculations.