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Dehnhard, D.
Minnesota Univ., Minneapolis (USA)1980
Minnesota Univ., Minneapolis (USA)1980
AbstractAbstract
[en] The elastic and inelastic scattering of π+ and π- by 13C, 16O, and 17O was studied at pion energies close to the (3,3) resonance. Data were taken at the Los Alamos Meson Physics Facility. Large asymmetries were observed, two of which are consistent with pure neutron and pure proton excitations. Transitions to strongly excited states of 13C are in strikingly good agreement with theoretical predictions of Lee and Kurath. In sharp contrast, strong disagreements are found for the weakly excited states. The asymmetries for 16O + π+- were interpreted as due to isospin mixing between the excited states. High-resolution data for (t,t') and (3He,3He') on 13C were taken to supplement the pion work. Asymmetries were found for the relative cross sections for some states. In studies of the heavy-ion-nucleus potential the effect of potential resonances on the elastic scattering of 16O + 28Si was found to be small. A close similarity between the elastic exchange amplitude at 1800 and the effect of the parity dependence on the elastic amplitude was found. Fits to the new data at 40 and 41.226 MeV required the use of a composite absorptive potential. The surface derivative part of this potential can be deduced from a coupled-channels calculation. 17 figures
Original Title
Univ. of Minnesota, June 1, 1979-May 31, 1980
Primary Subject
Source
Mar 1980; 54 p; Available from NTIS., PC A04/MF A01
Record Type
Report
Literature Type
Numerical Data; Progress Report
Report Number
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Dehnhard, D.
Minnesota Univ., Minneapolis (USA)1984
Minnesota Univ., Minneapolis (USA)1984
AbstractAbstract
[en] A large number of experiments were done using pion and proton beams at intermediate energies to investigate different excitation modes of the nucleus. Pions were found to be especially suited to excite magnetic transitions of high multipolarity (M4's). The isospin, or neutron/proton, structure of many transitions could be unraveled and detailed comparisons with the predictions of large-space shell-model calculations were successful in many cases. A few glaring exceptions were found to the general good agreement between theory and experiment. For the collectively enhanced electric quadrupole (E2) and octupole (E3) transitions, effective charge enhancements were needed to fit the pion and proton data. The polarization charges were usually found to be in good agreement with the results of electromagnetic measurements. Studies of the excitation of giant resonances by pion inelastic scattering indicated a large isovector component in the transitions to isoscalar giant resonances. This result, although theoretically unexpected, is supported by comparison of electron and alpha-particle scattering and requires further study. A very recent experiment on pion inelastic scattering from 4He showed little evidence for isospin mixing in this nucleus, in contrast to the conclusions drawn from (γ,n) and (γ,p) work. A high precision elastic π+ scattering experiment on 4He is underway. The work on heavy-ion elastic scattering was completed and terminated. Two experiments are presently being done at lower energies to supplement the work at intermediate energy
Primary Subject
Secondary Subject
Source
Jan 1984; 89 p; Available from NTIS, PC A05/MF A01 as DE84005762
Record Type
Report
Literature Type
Progress Report
Report Number
Country of publication
CALCIUM 48 TARGET, CARBON 12 TARGET, CARBON 13 TARGET, CARBON 14 TARGET, ELASTIC SCATTERING, ENERGY-LEVEL TRANSITIONS, GIANT RESONANCE, HEAVY ION REACTIONS, HELIUM 4 TARGET, INELASTIC SCATTERING, LEAD 208 TARGET, NITROGEN 15 TARGET, NUCLEAR STRUCTURE, OXYGEN 16 TARGET, OXYGEN 18 TARGET, PION REACTIONS, PROTON REACTIONS, RESEARCH PROGRAMS
Reference NumberReference Number
INIS VolumeINIS Volume
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Dehnhard, D.
Minnesota Univ., Minneapolis (USA)1986
Minnesota Univ., Minneapolis (USA)1986
AbstractAbstract
[en] A list of the experimental programs at the Los Alamos Meson Physics Facility is given. In addition, the personnel associated with these programs are listed
Primary Subject
Source
Jan 1986; 6 p; Available from NTIS, PC A02/MF A01 as DE86005990
Record Type
Report
Literature Type
Progress Report
Report Number
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Dehnhard, D.
Minnesota Univ., Minneapolis, MN (United States). Funding organisation: USDOE, Washington, DC (United States)1992
Minnesota Univ., Minneapolis, MN (United States). Funding organisation: USDOE, Washington, DC (United States)1992
AbstractAbstract
[en] π-meson and proton beams from the Los Alamos Meson Physics Facility (LAMPF) and the Indiana University Cyclotron Facility (IUCF) were used in scattering and reaction experiments on atomic nuclei. The experimental data allow tests of models of the reaction mechanism and of nuclear structure. For example, the asymmetries observed in a pion scattering experiment on polarized 13C nuclei were found to contain unique information on the isoscalar spin density. However, further experiments on polarized nuclei of simpler structure are needed to provide the data for a thorough analysis of the reaction mechanism. For this reason a pion scattering experiment on a polarized 3He target is planned and a high-resolution study on 6Li(π,π') will be done. An analysis of π-triton coincidence events from the 4He(π,π't)p reaction yielded evidence for direct triton knock-out from 4He. This work will be continued at higher incident pion energies. Additional work on the 4He(p,n) reaction at IUCF is planned to determine the isovector strength in mass-4 nuclei and the level parameters of 4Li
Primary Subject
Secondary Subject
Source
Feb 1992; 21 p; CONTRACT FG02-87ER40362; OSTI as DE92017980; NTIS; INIS; US Govt. Printing Office Dep
Record Type
Report
Literature Type
Progress Report
Report Number
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Dehnhard, D.
Minnesota Univ., Minneapolis, MN (USA)1991
Minnesota Univ., Minneapolis, MN (USA)1991
AbstractAbstract
[en] This paper discusses the following topics: pion scattering from polarized 13C; elastic scattering of π+ and π- from 4He; the 4He(π,π,t)p and 4He(π,π,d) reactions; contributions to the planning of PILAC; and the 4He(p,n)4Li reaction at 100, 147, and 200 MeV
Primary Subject
Secondary Subject
Source
Feb 1991; 36 p; CONTRACT FG02-87ER40362; OSTI as DE91009048; NTIS; INIS; US Govt. Printing Office Dep
Record Type
Report
Literature Type
Progress Report
Report Number
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Dehnhard, D.
Minnesota Univ., Minneapolis (USA). School of Physics and Astronomy1982
Minnesota Univ., Minneapolis (USA). School of Physics and Astronomy1982
AbstractAbstract
[en] Three experiments on pion inelastic scattering were performed during the last year at the Los Alamos Meson Physics Facility. Data reduction for the 14C experiment is complete and new information on the M4 strength in this nucleus was extracted. Data reduction for the 16O and 17O experiments is underway. Theoretical analyses of earlier data were continued and work on a consistent description of (π,π'), (e,e'), and (p,p') experiments on 16O and 13C proved to be very encouraging. In an experiment at the Swiss Institute for Nuclear Research (π,π'γ) angular correlation data were taken for the first time. The results support present theories on the importance of Δ-nucleus dynamics in pion scattering
Primary Subject
Source
Jan 1982; 71 p; Available from NTIS., PC A04/MF A01 as DE82011280
Record Type
Report
Literature Type
Progress Report
Report Number
Country of publication
ANGULAR DISTRIBUTION, CALCIUM 40 TARGET, CARBON 13, CARBON 13 TARGET, CARBON 14, CARBON 14 TARGET, DIFFERENTIAL CROSS SECTIONS, ELASTIC SCATTERING, ELECTRON REACTIONS, ENERGY-LEVEL TRANSITIONS, INELASTIC SCATTERING, M4-TRANSITIONS, OXYGEN 16 REACTIONS, OXYGEN 16 TARGET, OXYGEN 17 TARGET, PION REACTIONS, POLARIZATION-ASYMMETRY RATIO, PROTON REACTIONS, SILICON 28 TARGET
BARYON REACTIONS, BETA DECAY RADIOISOTOPES, BETA-MINUS DECAY RADIOISOTOPES, CARBON ISOTOPES, CROSS SECTIONS, DISTRIBUTION, EVEN-EVEN NUCLEI, EVEN-ODD NUCLEI, HADRON REACTIONS, HEAVY ION REACTIONS, ISOTOPES, LEPTON REACTIONS, LIGHT NUCLEI, MESON REACTIONS, MULTIPOLE TRANSITIONS, NUCLEAR REACTIONS, NUCLEI, NUCLEON REACTIONS, RADIOISOTOPES, SCATTERING, STABLE ISOTOPES, TARGETS, YEARS LIVING RADIOISOTOPES
Reference NumberReference Number
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Dehnhard, D.
Minnesota Univ., Minneapolis (USA)1985
Minnesota Univ., Minneapolis (USA)1985
AbstractAbstract
[en] The analysis of a large number of experiments has been completed. Among these are the studies of magnetic transitions by inelastic pion scattering on 14C, 15N, and 48Ca, and the octupole transitions in 17O. The experimental data provided stringent tests of large-space shell model calculations. Progress was made in the study of M1 transitions by proton scattering and in searches for evidence of a charge symmetry breaking force larger than the Coulomb force. Inelastic scattering of π+ and π- from 4He yielded π+/π- asymmetries completely consistent with isospin mixing due to the Coulomb force alone in sharp contrast to the conclusions drawn from photo-nucleon reactions. A study of π+ and π- scattering to the first 2+ states in nuclei between A = 18 and 42 revealed a systematic difference between the neutron transition matrix elements M/sub n/(T/sub z/ = +1) in the target nuclei and the proton matrix elements M/sub p/(T/sub z/ = -1) in the mirror nuclei although charge symmetry predicts M/sub n/(+1) = M/sub p/(-1). The work on the pion-nucleus reaction mechanism was continued by investigating the importance of two-step processes by coupled-channels calculations. Publications are listed
Primary Subject
Secondary Subject
Source
Jan 1985; 21 p; Available from NTIS, PC A02/MF A01 as DE85006700
Record Type
Report
Literature Type
Numerical Data; Progress Report
Report Number
Country of publication
COUPLED CHANNEL THEORY, DIFFERENTIAL CROSS SECTIONS, ELASTIC SCATTERING, ENERGY-LEVEL TRANSITIONS, EXPERIMENTAL DATA, GIANT RESONANCE, HELIUM 4 TARGET, INELASTIC SCATTERING, LIGHT NUCLEI, M1-TRANSITIONS, NUCLEAR STRUCTURE, PION MINUS REACTIONS, PION PLUS REACTIONS, PION REACTIONS, PROTON REACTIONS, RESEARCH PROGRAMS
Reference NumberReference Number
INIS VolumeINIS Volume
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Dehnhard, D.
Minnesota Univ., Minneapolis (USA)1988
Minnesota Univ., Minneapolis (USA)1988
AbstractAbstract
[en] A major effort was made in the study of proton and pion induced reactions on 4He. Spin transfer observables were measured for the first time for the 4He(/rvec p/,/rvec p/') reaction at 500 MeV at the Los Alamos Meson Physics Facility. The preliminary results show a spin-flip probability in the continuum of 4He which is much larger than the free proton-proton scattering value. The group also collaborated in the related 4He(/rvec p/,p'X) work done at the Indiana University Cyclotron Facility. The work on data reduction of the 4He(π+-,π+-'p) and 4He /plus/ π/+-/ elastic scattering experiments was continued and new data were taken for 12C(π+-,π+-p). A new analysis of 2+ states in 14C excited by π/sup /plus//, π/sup /minus//, and proton scattering was performed using large-space shell model calculations
Primary Subject
Secondary Subject
Source
Jan 1988; 36 p; Available from NTIS, PC A03/MF A01; 1 as DE88006389; Portions of this document are illegible in microfiche products.
Record Type
Report
Literature Type
Progress Report
Report Number
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Dehnhard, D.
Minnesota Univ., Minneapolis (USA)1981
Minnesota Univ., Minneapolis (USA)1981
AbstractAbstract
[en] Experiments performed at the Los Alamos Meson Physics Facility yielded very striking results. In inelastic pion scattering from 14C near the [3,3] resonance cross sections ratios R = sigma(π+)/sigma(π-) and R-1 = sigma(π-)/sigma(π+) were observed that are significantly larger than the free pion-nucleon values. These results were interpreted as due to strong cancellations of the neutron and proton components in the transition amplitude. Measurements of 13C(π,π') excitation functions between 100 and 300 MeV at two momentum transfers showed dramatically different energy dependencies for ΔS =0 and ΔS = 1 transitions. They were used to derive nuclear structure information on several highly excited states. Pion data for other nuclei (12C, 16O, 40Ca, etc.) were analyzed and information on isospin mixing, the double-charge-exchange reaction mechanism, and the excitation of collective states was extracted. Further data were taken with a 547 MeV proton beam on 13C. The data taking for the (t,t') and (3He,3He') reactions at the Los Alamos Van de Graaff has been completed. The continuing studies of the heavy-ion nucleus optical potential yielded information on very systematic dependencies of the potential depths on the incident energy
Primary Subject
Source
Mar 1981; 58 p; Available from NTIS., PC A04/MF A01
Record Type
Report
Literature Type
Numerical Data; Progress Report
Report Number
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
No abstract available
Original Title
25.0 MeV: angular distributions; 3He + Si, el scatt; 30P: J, π, S
Primary Subject
Source
Minnesota Univ., Minneapolis (USA). John H. Williams Lab. of Nuclear Physics; p. 55-64; Sep 1973
Record Type
Report
Literature Type
Progress Report
Report Number
Country of publication
BETA DECAY RADIOISOTOPES, BETA-PLUS DECAY RADIOISOTOPES, BORN APPROXIMATION, CHARGED PARTICLES, CROSS SECTIONS, DIRECT REACTIONS, DISTRIBUTION, ENERGY RANGE, EVEN-ODD NUCLEI, ISOTOPES, LIGHT NUCLEI, MEV RANGE, MINUTES LIVING RADIOISOTOPES, NUCLEAR REACTIONS, NUCLEI, ODD-ODD NUCLEI, PHOSPHORUS ISOTOPES, RADIOISOTOPES, SILICON ISOTOPES, STABLE ISOTOPES, TRANSFER REACTIONS
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