NON-SPIN-FLIP (HE-3, T) CHARGE-EXCHANGE AND ISOBARIC ANALOG STATES OF ACTINIDE NUCLEI STUDIED AT THETA=0-DEGREES, E(HE-3)=76 MEV AND 200 MEV

J JANECKE*, FD BECCHETTI, AM VANDENBERG, GPA BERG, MB GREENFIELD, MN HARAKEH, MA HOFSTEE, A NADASEN, DA ROBERTS, R SAWAFTA, JM SCHIPPERS, EJ STEPHENSON, DP STEWART, SY VANDERWERF

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    36 Citations (Scopus)

    Abstract

    The (He-3, t) charge-exchange reaction has been studied at theta = 0-degree-C and bombarding energies of E(He-3) = 76.5 MeV and 200 MeV. Spectra were measured using magnetic analysis for target nuclei of C-12, C-13, O-16, F-19, Si-28, Si-29, Si-30, Zr-90, Sn-117, Sn-120, (nat)Ta, (nat)W, Au-197, Pb-208, Th-230, Th-232, U-234, U-236, U-238 and Pu-244. The measurements at 76.5 MeV concentrated on the isobaric analog states of several actinide nuclei, particularly on their widths and the branching ratios for proton decay. Cross sections, Q-values and total widths were determined for the transitions to the isobaric analog states. Coulomb displacement energies derived from the measured Q-values display the influence of deformed nuclear shapes. Escape widths GAMMA-up and spreding widths GAMMA-down of the isobaric analog states in five actinide nuclei were deduced from the measured proton-decay branching ratios. They were found to be in agreement with predictions which postulate isospin mixing via the Coulomb force with the (T0-1)-component of the isovector giant monopole resonance. The measurements at 200 MeV were concerned with transitions to isobaric analog states in both light and heavy nuclei, including several actinide nuclei, but Gamow-Teller resonances and transitions to numerous other states were also observed. The measured cross sections for several transitions to isobaric analog states from Si-30 to Pb-208 were used to extract the effective interaction V(tau) for non-spin-flip (He-3, t) charge exchange at E(He-3) almost-equal-to 200 MeV. The interaction strength V(tau) decreases by a factor 0.6 when compared to previously measured values for the energy range E(He-3) = 65 to 90 MeV. An angular distribution from theta(t) = 0-degree to 16-degrees for the transition to the isobaric analog state in Sb-120 measured at E(He-3) = 200 MeV was found to be in very good agreement with microscopic calculations.

    Original languageEnglish
    Pages (from-to)1-35
    Number of pages35
    JournalNuclear Physics A
    Volume526
    Issue number1
    Publication statusPublished - 22-Apr-1991

    Keywords

    • C-12, O-16, AL-27, SI-28, TA, TH-230, TH-232, U-234, U-236, U-238,
    • (HE-3,T), E=76.5 MEV C-12, C-13, O-16, F-19, SI-28, ZR-90, SN-117,
    • SN-120, TA, W, AU-197, PB-208, TH-230, TH-232, U-234, U-238, PU-244,
    • (HE-3,T), E=200 MEV
    • MEASURED SIGMA (ET) THETA=0-DEGREES
    • SN-120 (HE-3,T), E=200 MEV
    • MEASURED SIGMA(THETA-T) FOR ISOBARIC ANALOG STATE (IAS),
    • THETA-T=0-DEGREES TO 16-DEGREES
    • TH-230, TH-232, U-234, U-236, U-238 (HE-3,TP), E=76.5 MEV
    • MEASURED PROTON DECAY FROM IAS, THETA(ET, EP, THETA-T,
    • THETA-P) FOR THETA-T=0-DEGREES, THETA-P=+120-DEGREES, +150-
    • DEGREES, -150-DEGREES
    • DEDUCED Q-VALUES FOR TRANSITIONS TO IAS, NB-90, SB-117, SN-120,
    • W-181, RE-184, HG-197, PB-208, PA-230, PA-232, NP-234, NP-236,
    • NP-238, AM-244, COULOMB DISPLACEMENT ENERGIES, TOTAL WIDTHS
    • GAMMA, ESCAPE WIDTHS GAMMA-UP, SPREADING WIDTHS GAMMA-DOWN
    • OF IAS, PB-208, PA-230, PA-232, NP-234, NP-236, NP-238, AM-244
    • EFFECTIVE INTERACTION V-TAU FOR NON-SPIN-FLIP CHARGE EXCHANGE
    • TRANSITIONS TO IAS, P-30, NB-90, SN-120, PB-208
    • ENRICHED AND LONG-LIVED RADIOACTIVE TARGETS
    • MAGNETIC SPECTROMETERS
    • ISOVECTOR GIANT-RESONANCES
    • COULOMB DISPLACEMENT ENERGIES
    • MONOPOLE RESONANCE
    • INTERMEDIATE ENERGIES
    • = 0-DEGREES
    • DECAY
    • DEPENDENCE
    • MODEL
    • LIGHT
    • PROBABILITY

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