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Title: Low-energy cross section of the {sup 7}Be(p,{gamma}){sup 8}B solar fusion reaction from the Coulomb dissociation of {sup 8}B

Abstract

An exclusive measurement of the Coulomb breakup of {sup 8}B into {sup 7}Be+p at 254A MeV was used to infer the low-energy {sup 7}Be(p,{gamma}){sup 8}B cross section. The radioactive {sup 8}B beam was produced by projectile fragmentation of 350A MeV {sup 12}C and separated with the FRagment Separator (FRS) at Gesellschaft fuer Schwerionenforschung in Darmstadt, Germany. The Coulomb-breakup products were momentum-analyzed in the KaoS magnetic spectrometer; particular emphasis was placed on the angular correlations of the breakup particles. These correlations demonstrate clearly that E1 multipolarity dominates within the angular cuts selected for the analysis. The deduced astrophysical S{sub 17} factors exhibit good agreement with the most recent direct {sup 7}Be(p,{gamma}){sup 8}B measurements. By using the energy dependence of S{sub 17} according to the recently refined cluster model for {sup 8}B of P. Descouvemont [Phys. Rev. C 70, 065802 (2004)], we extract a zero-energy S factor of S{sub 17}(0)=20.6{+-}0.8(stat){+-}1.2(syst) eV b. These errors do not include the uncertainty of the theoretical model to extrapolate to zero relative energy, estimated by Descouvemont to be about 5%.

Authors:
;  [1]; ; ; ; ; ; ; ; ; ;  [2]; ;  [2];  [3]; ; ;  [4]; ;  [5] more »;  [6] « less
  1. Institut fuer Physik mit Ionenstrahlen, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)
  2. Gesellschaft fuer Schwerionenforschung, D-64220 Darmstadt (Germany)
  3. (Germany)
  4. Phillips-Universitaet Marburg, D-35032 Marburg (Germany)
  5. Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany)
  6. University of Connecticut, Groton, Connecticut 06340 (United States) (and others)
Publication Date:
OSTI Identifier:
20771235
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 73; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevC.73.015806; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ANGULAR CORRELATION; BORON 8; CAPTURE; CARBON 12; CLUSTER MODEL; COSMIC NEUTRINOS; CROSS SECTIONS; DISSOCIATION; ENERGY DEPENDENCE; LITHIUM 7 TARGET; MEV RANGE; NUCLEAR FRAGMENTATION; PROTON REACTIONS

Citation Formats

Schuemann, F., Strieder, F., Typel, S., Hammache, F., Suemmerer, K., Cortina, D., Geissel, H., Koczon, P., Kurz, N., Schwab, E., Senger, P., Sun Zhiyu, Uhlig, F., Sturm, C., Technische Universitaet Darmstadt, D-64289 Darmstadt, Boettcher, I., Kohlmeyer, B., Menzel, M., Foerster, A., Oeschler, H., and Gai, M. Low-energy cross section of the {sup 7}Be(p,{gamma}){sup 8}B solar fusion reaction from the Coulomb dissociation of {sup 8}B. United States: N. p., 2006. Web. doi:10.1103/PhysRevC.73.015806.
Schuemann, F., Strieder, F., Typel, S., Hammache, F., Suemmerer, K., Cortina, D., Geissel, H., Koczon, P., Kurz, N., Schwab, E., Senger, P., Sun Zhiyu, Uhlig, F., Sturm, C., Technische Universitaet Darmstadt, D-64289 Darmstadt, Boettcher, I., Kohlmeyer, B., Menzel, M., Foerster, A., Oeschler, H., & Gai, M. Low-energy cross section of the {sup 7}Be(p,{gamma}){sup 8}B solar fusion reaction from the Coulomb dissociation of {sup 8}B. United States. doi:10.1103/PhysRevC.73.015806.
Schuemann, F., Strieder, F., Typel, S., Hammache, F., Suemmerer, K., Cortina, D., Geissel, H., Koczon, P., Kurz, N., Schwab, E., Senger, P., Sun Zhiyu, Uhlig, F., Sturm, C., Technische Universitaet Darmstadt, D-64289 Darmstadt, Boettcher, I., Kohlmeyer, B., Menzel, M., Foerster, A., Oeschler, H., and Gai, M. Sun . "Low-energy cross section of the {sup 7}Be(p,{gamma}){sup 8}B solar fusion reaction from the Coulomb dissociation of {sup 8}B". United States. doi:10.1103/PhysRevC.73.015806.
@article{osti_20771235,
title = {Low-energy cross section of the {sup 7}Be(p,{gamma}){sup 8}B solar fusion reaction from the Coulomb dissociation of {sup 8}B},
author = {Schuemann, F. and Strieder, F. and Typel, S. and Hammache, F. and Suemmerer, K. and Cortina, D. and Geissel, H. and Koczon, P. and Kurz, N. and Schwab, E. and Senger, P. and Sun Zhiyu and Uhlig, F. and Sturm, C. and Technische Universitaet Darmstadt, D-64289 Darmstadt and Boettcher, I. and Kohlmeyer, B. and Menzel, M. and Foerster, A. and Oeschler, H. and Gai, M.},
abstractNote = {An exclusive measurement of the Coulomb breakup of {sup 8}B into {sup 7}Be+p at 254A MeV was used to infer the low-energy {sup 7}Be(p,{gamma}){sup 8}B cross section. The radioactive {sup 8}B beam was produced by projectile fragmentation of 350A MeV {sup 12}C and separated with the FRagment Separator (FRS) at Gesellschaft fuer Schwerionenforschung in Darmstadt, Germany. The Coulomb-breakup products were momentum-analyzed in the KaoS magnetic spectrometer; particular emphasis was placed on the angular correlations of the breakup particles. These correlations demonstrate clearly that E1 multipolarity dominates within the angular cuts selected for the analysis. The deduced astrophysical S{sub 17} factors exhibit good agreement with the most recent direct {sup 7}Be(p,{gamma}){sup 8}B measurements. By using the energy dependence of S{sub 17} according to the recently refined cluster model for {sup 8}B of P. Descouvemont [Phys. Rev. C 70, 065802 (2004)], we extract a zero-energy S factor of S{sub 17}(0)=20.6{+-}0.8(stat){+-}1.2(syst) eV b. These errors do not include the uncertainty of the theoretical model to extrapolate to zero relative energy, estimated by Descouvemont to be about 5%.},
doi = {10.1103/PhysRevC.73.015806},
journal = {Physical Review. C, Nuclear Physics},
number = 1,
volume = 73,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}
  • The cross section for Coulomb dissociation of [sup 8]B---the [sup 208]Pb([sup 8]B,[sup 7]Be [ital p])[sup 208]Pb reaction---was measured using a [sup 8]B radioactive beam of 46.5 MeV/nucleon energy, and the cross section for the [sup 7]Be([ital p],[gamma])[sup 8]B capture reaction was deduced at low energies; [ital E][sub c.m.]=0.6[minus]1.7 MeV. The extracted astrophysical [ital S][sub 17] factors were found to be consistent with the values measured by Vaughn [ital et] [ital al]. and Filippone [ital et] [ital al]. This result encourages further experimental studies extended to lower relative energies for a new determination of the [ital S][sub 17] value relevant tomore » the [sup 8]B solar neutrino flux.« less
  • The Coulomb dissociation (CD) of {sup 8}B has emerged as a landmark testing ground of the very method of CD for measuring the cross section of the low-energy {sup 7}Be(p,{gamma}){sup 8}B direct capture (DC) reaction. Recent claims of evidence of slope difference between CD and DC results are critically examined. We include all relevant RIKEN2 data and all previously published DC data, and we examine the extracted so-called average scale-independent slope (b). The parametrization used by the Seattle group to extract the so-called b-slope parameter is also examined at energies above 300 keV. Considering the physical slope (S{sup '}=dS/dE) abovemore » 300 keV, we observe a (1.7{sigma}) agreement between slopes (S{sup '}) measured in CD and DC above 300 keV. The claim that S{sub 17}(0) values extracted from CD data are inconsistent and lower than DC results arises from a neglect of substantial systematic uncertainty of low-energy CD data. A consideration of the published CD S{sub 17}(0) results yields very consistent S{sub 17}(0) values that agree with most recent DC measurements. The recent correction of the b-slope parameter suggested by Esbensen, Bertsch, and Snover (EBS) was applied to the wrong b slope calculated using part of the RIKEN2 data. When the correct slope of the RIKEN2 data is used, the EBS correction in fact leads to a substantial disagreement between the slopes of the RIKEN2 data and DC data. In spite of an agreement between CD and DC data neither allow for extracting the slope above 300 keV with high accuracy. Uncertainty of the slope (S{sup '}) leads to an additional uncertainty of the extrapolated S{sub 17}(0). The slope of the astrophysical cross-section factor S{sub 17} must be measured with high precision to enable extraction of the d/s ratio and a high-precision extrapolation of S{sub 17}(0)« less
  • We have calculated the [ital E]1 and [ital E]2 contributions to the low-energy [sup 8]B+[sup 208]Pb[r arrow][ital p]+[sup 7]Be+[sup 208]Pb Coulomb dissociation cross sections using the kinematics of a recent experiment at RIKEN. Using a potential model description of the [sup 7]Be([ital p],[gamma])[sup 8]B reaction, we find that the [ital E]2 contributions cannot [ital a] priori be ignored in the analysis of the data. Its inclusion reduces the extracted [sup 7]Be([ital p],[gamma])[sup 8]B [ital S] factor at solar energies by about 25%.
  • The {ital E}2 cross section calculated by Langanke and Shoppa for the RIKEN experiment on the Coulomb dissociation of {sup 8}B uses {ital E}2 nuclear matrix element from one specific model. Other nuclear models predict a considerably smaller {ital E}2 cross section (by approximately a factor of 3 to 4), and Langanke and Shoppa appear to assume the most optimistic scenario, predicting a large {ital E}2 cross section. We also note that Barker has already criticized the nuclear model used by Langanke and Shoppa. A {ital model} {ital independent} chi-square analysis of the RIKEN data suggest the best fit formore » the current RIKEN data is obtained with {ital E}1 amplitudes only. The upper limit (90% confidence) on the {ital E}2 component derived from our chi-square analysis is considerably smaller than that used by Langanke and Shoppa. The {ital model} {ital dependent} analysis of Langanke and Shoppa should not be considered as a correction to the RIKEN result, as claimed, and their quoted {ital S}{sub 17}(0) is not substantiated.« less
  • This is a reply to the preceding Comment.