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INVESTIGATION OF THE (10B,6Li* (3+, 2.18 MeV)) REACTION AS A METHOD FOR alpha-CLUSTER TRANSFER STUDIES

Description: The four-nucleon transfer reaction {sup 12}C({sup 10}B, {sup 6}Li*(2.18 MeV)) {sup 16}O has been studied at 68 MeV by coincidence measurement of the d + {alpha} breakup particles. The reaction is quite selective as is observed in other established {alpha}-transfer reactions.
Date: July 1, 1980
Creator: Bice, A.N.; Shotter, A.C.; Stahel, D.P. & Cerny, J.
Partner: UNT Libraries Government Documents Department

Observation of Au + Au --> Au + Au + rho(0) and Au + Au --> Au* + Au* + rho(0) with STAR

Description: We report the first observation of the reactions Au + Au {yields} Au + Au + {rho}{sup 0} and Au + Au {yields} Au* + Au* + {rho}{sup 0} with the STAR detector. The {rho} are produced at small perpendicular momentum, as expected if they couple coherently to both nuclei. We discuss models of vector meson production and the correlation with nuclear breakup, and present a fundamental test of quantum mechanics that is possible with the system.
Date: March 10, 2001
Creator: Klein, Spencer & Collaboration, STAR
Partner: UNT Libraries Government Documents Department

In-beam gamma-ray spectrometric measurements of multi-body breakup reactions for E{sub n} between threshold and 40 MeV

Description: A system for in-beam gamma-ray spectrometric measurements to study inelastic neutron scattering has been extended to increasing incident neutron energies to study multi-body breakup reactions on light and medium-weight elements. The (n,2n{gamma}) cross sections are generally the largest; however, reactions of the types (n,{alpha}{gamma}), (n,np{gamma}) and (n,3n{gamma}) have been observed. In addition to improved understanding of reaction channels studied by other techniques, this method provides data for some reactions, e.g. {sup 56}Fe(n,3n){sup 54}Fe, which have not been observed previously.
Date: April 1995
Creator: Dickens, J. K. & Larson, D. C.
Partner: UNT Libraries Government Documents Department

Momentum distributions in breakup reactions

Description: Measurements of the breakup reactions: {sup 11}Be {yields} {sup 10}Be+n and{sup 8} {yields} {sup 7}Be+p are analyzed in a single-particle description. The signature of various structure properties associated with the valence nucleon axe discussed, as well as the significance of the different reaction mechanisms, namely Coulomb dissociation, stripping and nuclear induced diffraction.
Date: February 1, 1996
Creator: Esbensen, H.
Partner: UNT Libraries Government Documents Department

Scattering length measurements from radiative pion capture and neutron-deuteron breakup

Description: The neutron-neutron and neutron-proton {sup 1}S{sub 0} scattering lengths a{sub nn} and a{sub np}, respectively, were determined simultaneously from the neutron-deuteron breakup reaction. Their comparison with the recommended values obtained from two body reactions gives a measure of the importance of three-nucleon force effects in the three-nucleon continuum. In order to check on the result obtained for a{sub nn} from the two-body {pi}{sup {minus}}-d capture reaction, a new measurement was performed at LANL. Preliminary results of the three experiments are given.
Date: July 1, 1997
Creator: Gibson, B. F.; Tornow, W. & Carman, T. S.
Partner: UNT Libraries Government Documents Department

Progress report, August 1, 1980-May 31, 1982

Description: Progress is briefly described on the following topics: (1) effect of deuteron breakup on elastic deuteron scattering cross sections and polarizations; (2) the validity of the discretization method; (3) the effect of breakup on rearrangement reactions; (4) formulation in terms of hyperspherical harmonics of the effect of breakup in deuteron-nucleous collisions; and (5) formulation of scattering theory in terms of a basis of positive energy Weinberg functions. (WHK)
Date: February 10, 1982
Creator: Rawitscher, G.H.
Partner: UNT Libraries Government Documents Department

A PROPOSAL TO MEASURE THE CROSS SECTION OF THE SPACE STAR IN NEUTRON-DEUTERON BREAKUP IN A RECOIL GEOMETRY SETUP

Description: Nucleon-deuteron (Nd) breakup is an important tool for obtaining a better understanding of three-nucleon (3N) dynamics and for developing meson exchange descriptions of nuclear systems. The kinematics of the nd breakup reaction enable observables to be studied in a variety of exit-channel configurations that show sensitivity to realistic nucleon-nucleon (NN) potential models and three-nucleon force (3NF) models. Rigorous 3N calculations give very good descriptions of most 3N reaction data. However, there are still some serious discrepancies between data and theory. The largest discrepancy observed between theory and data for nd breakup is for the cross section for the space-star configuration. This discrepancy is known as the “Space star Anomaly”. Several experimental groups have obtained results consistent with the “Space Star Anomaly”, but it is important to note that they all used essentially the same experimental setup and so their experimental results are subject to the same systematic errors. We propose to measure the space-star cross-section at the Triangle Universities Nuclear Laboratory (TUNL) using an experimental technique that is significantly different from the one used in previous breakup experiments. This technique has been used by a research group from the University of Bonn to measure the neutron-neutron scattering length. There are three possible scenarios for the outcome of this work: 1) the new data are consistent with previous measurements; 2) the new data are not in agreement with previous measurements, but are in agreement with theory; and 3) the new data are not in agreement with either theory or previous measurements. Any one of the three scenarios will provide valuable insight on the Space Star Anomaly.
Date: September 30, 2009
Creator: III, Benjamin J. Crowe
Partner: UNT Libraries Government Documents Department

Theory of hybrid nuclear reactions

Description: A theory of hybrid nuclear reactions, which are partially direct and partially compound, is presented. We review first the formulation of the theory, based on the optical theorem, and then its applications to a few example reactions. Discussions will be given on the physical picture (deep peripheral nature) of such hybrid processes emerging from the numerical studies. 25 references, 10 figures.
Date: January 1, 1983
Creator: Udagawa, T.
Partner: UNT Libraries Government Documents Department

Study of Nuclear Reactions with Radioactive {sup 17}F at HRIBF

Description: Radioactive {sup 17}F beams were produced at the Holifield Radioactive Ion Beam Facility (HRIBF) using the Isotope Separator On-Line (ISOL) technique. Two of the experiments using accelerated {sup 17}F beams to study reaction mechanisms are presented: the simultaneous emission of two protons from a resonance in {sup 18}Ne and the breakup of {sup 17}F by {sup 208}Pb.
Date: November 7, 2001
Creator: Liang, J.F.
Partner: UNT Libraries Government Documents Department

Ultra-peripheral collisions of relativistic heavy ions

Description: We report the first observation of exclusive {rho} production in ultra-peripheral collisions at RHIC. The {rho} are produced electromagnetically at large impact parameters where no hadronic interactions occur. The produced {rho} have a small perpendicular momentum, consistent with production that is coherent on both the photon emitting and scattering nuclei. We observe both exclusive {rho} production, and {rho} production accompanied by electromagnetic dissociation of both nuclei. We discuss models of vector meson production and the correlation with nuclear breakup. We also observe e{sup +}e{sup -} pair production in these ultra-peripheral collisions.
Date: January 1, 2001
Creator: Klein, S. & Collaboration, STAR
Partner: UNT Libraries Government Documents Department

Photo- and electro-disintegration of {sup 3}He at threshold and pd radiative capture

Description: The present work reports results for: (1) pd radiative capture observables measured at center-of-mass (c.m.) energies in the range 0--100 keV and at 2 MeV by the TUNL and Wisconsin groups, respectively; (2) contributions to the Gerasimov-Drell-Hearn (GDH) integral in {sup 3}He from the two- up to the three-body breakup thresholds, compared to experimental determinations by the TUNL group in this threshold region; (3) longitudinal, transverse, and interference response functions measured in inclusive polarized electron scattering off polarized {sup 3}He at excitation energies below the threshold for breakup into ppn, compared to unpolarized longitudinal and transverse data from the Saskatoon group. The calculations are based on pair-correlated-hyperspherical-harmonics bound and continuum wave functions obtained from a realistic Hamiltonian consisting of the Argonne {upsilon}{sub 18} two-nucleon and Urbana IX three-nucleon interactions. The electromagnetic current operator includes one- and two- body components, leading terms of which are constructed from the Argonne {upsilon}{sub 18} interaction (specifically, its charge-independent part). Two-body currents associated with {Delta}-isobar degrees of freedom are treated non-perturbatively via the transition-correlation-operator method. The theoretical predictions obtained by including only one-body currents are in violent disagreement with data. These differences between theory and experiment are, to a large extent, removed when two-body currents are taken into account, although some rather large discrepancies remain in the c.m. energy range 0--100 keV, particularly for the pd differential cross section {sigma}({theta}) and tensor analyzing power T{sub 20}({theta}) at small angles, and contributions to the GDH integral. A rather detailed analysis indicated that these discrepancies have, in large part, a common origin, and can be traced back to an excess strength obtained in the theoretical calculation of the E{sub 1} reduced matrix element associated with the pd channel having L,S,J = 1, 1/2, 3/2. It is suggested that this lack of E{sub 1} strength observed experimentally might ...
Date: November 1, 1999
Creator: Viviani, M.; Kievsky, A.; Marcucci, L.E.; Rosati, S. & Schiavilla, R.
Partner: UNT Libraries Government Documents Department

Coulomb reacceleration as a clock for nuclear reactions -- II

Description: Reacceleration effects in the Coulomb breakup of nuclei are modeled with the two-dimensional time-dependent Schroedinger equation, extending a previous one-dimensional study. The present model better describes the individual contributions of longitudinal and transverse forces to the breakup and reacceleration. Reacceleration effects are found to preserve a strong memory of the pre-breakup phase of the reaction, as was concluded with the one-dimensional model.
Date: March 1, 1994
Creator: Bertulani, C. A. & Bertsch, George F.
Partner: UNT Libraries Government Documents Department

Characterization of a Tunable Quasi-Monoenergetic Neutron Beamfrom Deuteron Breakup

Description: A neutron irradiation facility is being developed at the88-Inch Cyclotron at Lawrence Berkeley National Laboratory for thepurposes of measuring neutron reaction cross sections on radioactivetargets and for radiation effects testing. Applications are of benefit tostockpile stewardship, nuclear astrophysics, next generation advancedfuel reactors, and cosmic radiation biology and electronics in space. Thefacility will supply a tunable, quasi-monoenergetic neutron beam in therange of 10-30 MeV or a white neutron source, produced by deuteronbreakup reactions on thin and thick targets, respectively. Because thedeuteron breakup reaction has not been well studied at intermediateincident deuteron energies, above the target Coulomb barrier and below 56MeV, a detailed characterization was necessary of the neutron spectraproduced by thin targets.Neutron time of flight (TOF) methods have beenused to measure the neutron spectra produced on thin targets of low-Z(titanium) and high-Z (tantalum) materials at incident deuteron energiesof 20 MeV and 29 MeV at 0 deg. Breakup neutrons at both energies fromlow-Z targets appear to peak at roughly half of the available kineticenergy, while neutrons from high-Z interactions peak somewhat lower inenergy, owing to the increased proton energy due to breakup within theCoulomb field. Furthermore, neutron spectra appear narrower for high-Ztargets. These centroids are consistent with recent preliminary protonenergy measurements using silicon telescope detectors conducted at LBNL,though there is a notable discrepancy with spectral widths.
Date: December 14, 2006
Creator: Bleuel, D.L.; McMahan, M.A.; Ahle, L.; Barquest, B.R.; Cerny, J.; Heilbronn, L.H. et al.
Partner: UNT Libraries Government Documents Department

Deuteron breakup mechanism in the intermediate-energy region

Description: In an earlier investigation, we have explored the possibility of explaining the deuteron breakup mechanism in terms of the Udagawa and Tannura (UT) formalism of the breakup-fusion process. The experimental doubly differential data were very well reproduced for the test case studies. However, the application of UT formalism of the spirit of DWBA involves the use of optical-model parameters for different nuclei and at different energies. The optical model parameters are not always unique. In the present study we investigate the deuteron breakup mechanism in terms of the semiclassical models of Serber (for the nuclear interaction part) and Dancoff (for the electromagnetic dissociation). In the case of Serber model the modification due to the finite range of the deuteron and the Glauber correction for the diffractive disassociation are considered. The modified deuteron breakup cross section either for the (d,p) or the (d,n) process is proportional to the product of the target radius and the deuteron radius (R{sub target} {center dot} R{sub deuteron}). The predicted proton/neutron spectrum is centered around 1/2 E{sub d} and forward peaked. The Coulomb dissociation of deuteron is attributed to the deuteron dipole excitation in the presence of the nuclear Coulomb field. The neutron/proton spectrum, resulting from the Coulomb breakup of the deuteron, is highly forward peaked and also centered around 1/2 E{sub d}. The systematics of the deuteron breakup neutron/proton spectra are investigated for medium to heavy target nuclei at 50--200 MeV deuteron energies. 10 refs., 4 figs.
Date: January 1, 1991
Creator: Divadeenam, M. & Ward, T.E.
Partner: UNT Libraries Government Documents Department

Tensor analyzing powers in deuteron--proton elastic scattering and the breakup reaction at 45. 4 MeV

Description: Recently the tensor analyzing powers in vector d + p elastic scattering and in the breakup reaction at E/sub d/ = 45.4 MeV were measured. The elastic results now establish a rather complete set of polarization data in nucleon--deuteron scattering at E/sub N/ = 22.7 MeV, which consists of the proton analyzing power, the deuteron vector and tensor analyzing powers, and vector polarization transfer measurements, as well. 8 references. (JFP)
Date: August 1, 1978
Creator: Conzett, H.E.
Partner: UNT Libraries Government Documents Department

Coulomb dissociation and momentum distributions for {sup 11}Li {yields} {sup 9}Li + n + n breakup reactions

Description: Momentum distributions for the {sup 11}Li {yields} {sup 9}Li+n+n breakup reaction, generated by Coulomb dipole excitations, axe calculated in a 3-body model for {sup 11}Li. The relative momentum distribution of the two neutrons is in good agreement with recent 3-body coincidence measurements but the momentum distribution for the {sup 9}Li recoil and the decay energy spectrum are much narrower than observed. These discrepancies may be due to higher order dynamical effects which have been ignored.
Date: March 1, 1993
Creator: Esbensen, Henning
Partner: UNT Libraries Government Documents Department

Large amplitude collective nuclear motion and soliton concept

Description: An application of a soliton theory methods to some nonlinear problems in low and intermediate energies (E {approx} 10--100MeV/nucleon) nucleus - nucleus collisions are presented. Linear and nonlinear excitations of the nuclear density are investigated in the framework of nuclear hydrodynamics. The problem of dynamical instability and clusterization phenomena in a breakup of excited nuclear systems are considered from the points of view of a soliton concept.
Date: December 31, 1993
Creator: Kartavenko, V. G.
Partner: UNT Libraries Government Documents Department

Analyzing-power formalism for three-body final states

Description: Various relations important for extraction of analyzing powers from data on reactions involving three particles in the final state were derived. Several of the results pertinent for spin-1/2 and spin-1 polarized beams are presented here. These may be used in analysis of the /sup 1/H(d-vector,pp)n reaction. 3 figures. (RWR)
Date: January 1, 1980
Creator: Ohlsen, G.G.; Brown, R.E.; Correll, F.D. & Hardekopf, R.A.
Partner: UNT Libraries Government Documents Department

Tensor analyzing powers in the /sup 1/H(d vector,pp)n reaction at 16 MeV. I. The symmetric, constant-relative-energy configurations

Description: Experimental results for the tensor analyzing powers A/sub xx/ and A/sub yz/ in the /sup 1/H(d-vector, pp)n reaction at 16 MeV for a series of symmetric, constant-relative-energy configurations are reported and compared with the results of recent Faddeev calculations using a separable NN potential. In general, the agreement seems fairly good, although there is some evidence that the measured values of A/sub yz/ tend to be slightly smaller than the prediction, whereas for A/sub xx/ the opposite appears to be true. 1 figure, 1 table. (RWR)
Date: January 1, 1980
Creator: Correll, F.D.; Ohlsen, G.G.; Brown, R.E.; Hardekopf, R.A.; Jarmie, N.; Schwandt, P. et al.
Partner: UNT Libraries Government Documents Department

Recent results from the Bevalac

Description: In a collision between a 1.8 GeV/amu argon ion and a lead target, the overlapping regions of projectile and target undergo violent interaction while the non-overlapping regions either continue with beam velocity and break up into projectile fragments or remain at rest and break into target fragments. Projectile fragements are the easiest to study; the participants, in the mid-rapidity region, are the next easiest, while the target fragments have not been extensively studied, except by radiochemistry techniques. This talk concentrates (with the exception of a discussion of anomalous projectile fragments) on the participant region, where one would expect to find high densities and temperatures and where evidence of any phase transition might be found. The extensive evidence for a high degree of equilibration at Bevalac energies is omitted, even though the stopping power of nuclei is crucial for possible studies at higher energies.
Date: June 1, 1982
Creator: Pugh, H.G.
Partner: UNT Libraries Government Documents Department

Photodisintegration of the deuteron with polarized photons from LEGS

Description: An experiment is described which will measure the d(..gamma..,p) reaction with polarized photon beams from LEGS ranging in energy from 50 MeV to 530 MeV. The data will yield a new high-resolution high-statistics determination of the total unpolarized cross section, will isolate for the first time the polarization dependent part of the reaction, and will measure the photon-beam asymmetry with much higher resolution and accuracy than available from existing data. These will provide one of the most stringent tests for models of the nuclear force. In addition, high-resolution data will be taken with both linear and circularly-polarized ..gamma.. rays to search for the effects of bibaryons.
Date: January 1, 1985
Creator: Dowell, D.H.; Giordano, G.; Kistner, O.; Matone, G.; Sandorfi, A.M.; Schaerf, C. et al.
Partner: UNT Libraries Government Documents Department

Physics with polarized photons

Description: The role that polarization can play in the interaction of real and virtual photons with nuclear matter is considered. Linear, circular, and elliptical polarization are considered. Photodisintegration of the deuteron with linearly polarized photons is then examined, followed by use of circularly polarized photons with a polarized target. 30 refs., 4 figs. (LEW)
Date: October 1, 1985
Creator: Matone, G.
Partner: UNT Libraries Government Documents Department