The spin observable D NN′ (θ) was measured for ( ) at 135 MeV on 16 O, 40 Ca, 48 Ca, and 208 Pb. ... more The spin observable D NN′ (θ) was measured for ( ) at 135 MeV on 16 O, 40 Ca, 48 Ca, and 208 Pb. Data for 16 O and 40 Ca are compared with distorted-wave impulse approximation (DWIA) calculations with Tamm-Dancoff (TDA) wave functions; the D NN′ data generally ...
ABSTRACT The excitation-energy distribution of transition strength to 1+ states was measured for ... more ABSTRACT The excitation-energy distribution of transition strength to 1+ states was measured for the 208Pb(p,n)208Bi reaction at 134.3 MeV for excitation energies up to 38 MeV. Structures observed in neutron time-of-flight spectra with forward-peaked (ΔL=0) angular distributions were identified as 1+ states, except for the transition to the 0+ isobaric analog state. The 1+ strength in these structures was extracted by normalizing the yield above a fitted polynomial background to the Fermi transition strength localized in the isobaric analog state. The Gamow-Teller strength observed in the 1+ peaks is 56% of the 3(N-Z) sum rule when the strength of the β+ transitions is assumed to be zero; 45% of 3(N-Z) is observed in the giant resonance and 10% is observed in structures below the giant resonance. Based on a multipole decomposition analysis, an upper limit on the 1+ strength in the apparent continuum to 38 MeV of excitation energy is estimated to be 37% of 3(N-Z). These results are compared with predictions from a shell model that includes a pairing force and a long-range Gamow-Teller force in both the parent and daughter nuclei.
The ground state of 6Li is examined through a comparison of the reactions 6Li(p,p alpha )d and 6L... more The ground state of 6Li is examined through a comparison of the reactions 6Li(p,p alpha )d and 6Li(p,p alpha )np at a bombarding energy of 39.8 MeV. Evidence is presented for the existence of a cluster structure of alpha particle plus neutron-proton pair within the ground state of 6Li.
We measured the complete set of polarization-transfer observables (D_ij) for the ^13C(p,n)^13N an... more We measured the complete set of polarization-transfer observables (D_ij) for the ^13C(p,n)^13N and ^15N(p,n)^15O reactions at 135 MeV. From the D_ijs we constructed the spin-independent, spin-longitudinal, and spin-transverse responses [1] D_0, D_q, Dn and D_p. From these responses we extracted, in a model-independent way, the Δ J=0 and Δ J=1 (``F'' and ``GT'') fractions of the J^π=1/2^-arrow1/2^- g.s. to g.s. transitions for these reactions. The ``F'' fraction, f_F=D_0(0^circ); the ``GT'' fraction, f_GT=D_q(0^circ)+D_n(0^circ)+D_p(0^circ)= 1- D_0(0^circ). The extracted GT fractions, f_GT, are substantially larger than one would predict from β-decay matrix elements and the systematics of the (p,n) reaction on even-A nuclei. These results confirm earlier, model-dependent determinations of f_GT obtained from the (p,n) reaction on ^13C, ^15N and ^39K at other energies [2], [3], [4], indicating that considerable caution must be used when extracting B(GT) ...
... for his advice and help in performing the DWBA cal-culations and to Professor BL Cohen andPro... more ... for his advice and help in performing the DWBA cal-culations and to Professor BL Cohen andProfessor RM Drisko ... Bombardment of Li7, C12, and O16t F. AJZENBERG-SELOVE AND JW WATSON IIaverford College, Haverford, Pennsylvania AND R. MIDDLETON University of ...
... J. 429 (1994) 400. (1 II JM Ryan, Solar Physics with the Compton Gamma Ray Observatory, in: T... more ... J. 429 (1994) 400. (1 II JM Ryan, Solar Physics with the Compton Gamma Ray Observatory, in: The Second Compton Symposium, College Park, MD, 1993, AIP Conference Proceedings 304, eds. ... Rev. C 24 (1981) 335. [201 TN Taddeucci et al., Nucl. Phys. A 469 (1987) 125. ...
The spin observable D NN′ (θ) was measured for ( ) at 135 MeV on 16 O, 40 Ca, 48 Ca, and 208 Pb. ... more The spin observable D NN′ (θ) was measured for ( ) at 135 MeV on 16 O, 40 Ca, 48 Ca, and 208 Pb. Data for 16 O and 40 Ca are compared with distorted-wave impulse approximation (DWIA) calculations with Tamm-Dancoff (TDA) wave functions; the D NN′ data generally ...
ABSTRACT The excitation-energy distribution of transition strength to 1+ states was measured for ... more ABSTRACT The excitation-energy distribution of transition strength to 1+ states was measured for the 208Pb(p,n)208Bi reaction at 134.3 MeV for excitation energies up to 38 MeV. Structures observed in neutron time-of-flight spectra with forward-peaked (ΔL=0) angular distributions were identified as 1+ states, except for the transition to the 0+ isobaric analog state. The 1+ strength in these structures was extracted by normalizing the yield above a fitted polynomial background to the Fermi transition strength localized in the isobaric analog state. The Gamow-Teller strength observed in the 1+ peaks is 56% of the 3(N-Z) sum rule when the strength of the β+ transitions is assumed to be zero; 45% of 3(N-Z) is observed in the giant resonance and 10% is observed in structures below the giant resonance. Based on a multipole decomposition analysis, an upper limit on the 1+ strength in the apparent continuum to 38 MeV of excitation energy is estimated to be 37% of 3(N-Z). These results are compared with predictions from a shell model that includes a pairing force and a long-range Gamow-Teller force in both the parent and daughter nuclei.
The ground state of 6Li is examined through a comparison of the reactions 6Li(p,p alpha )d and 6L... more The ground state of 6Li is examined through a comparison of the reactions 6Li(p,p alpha )d and 6Li(p,p alpha )np at a bombarding energy of 39.8 MeV. Evidence is presented for the existence of a cluster structure of alpha particle plus neutron-proton pair within the ground state of 6Li.
We measured the complete set of polarization-transfer observables (D_ij) for the ^13C(p,n)^13N an... more We measured the complete set of polarization-transfer observables (D_ij) for the ^13C(p,n)^13N and ^15N(p,n)^15O reactions at 135 MeV. From the D_ijs we constructed the spin-independent, spin-longitudinal, and spin-transverse responses [1] D_0, D_q, Dn and D_p. From these responses we extracted, in a model-independent way, the Δ J=0 and Δ J=1 (``F'' and ``GT'') fractions of the J^π=1/2^-arrow1/2^- g.s. to g.s. transitions for these reactions. The ``F'' fraction, f_F=D_0(0^circ); the ``GT'' fraction, f_GT=D_q(0^circ)+D_n(0^circ)+D_p(0^circ)= 1- D_0(0^circ). The extracted GT fractions, f_GT, are substantially larger than one would predict from β-decay matrix elements and the systematics of the (p,n) reaction on even-A nuclei. These results confirm earlier, model-dependent determinations of f_GT obtained from the (p,n) reaction on ^13C, ^15N and ^39K at other energies [2], [3], [4], indicating that considerable caution must be used when extracting B(GT) ...
... for his advice and help in performing the DWBA cal-culations and to Professor BL Cohen andPro... more ... for his advice and help in performing the DWBA cal-culations and to Professor BL Cohen andProfessor RM Drisko ... Bombardment of Li7, C12, and O16t F. AJZENBERG-SELOVE AND JW WATSON IIaverford College, Haverford, Pennsylvania AND R. MIDDLETON University of ...
... J. 429 (1994) 400. (1 II JM Ryan, Solar Physics with the Compton Gamma Ray Observatory, in: T... more ... J. 429 (1994) 400. (1 II JM Ryan, Solar Physics with the Compton Gamma Ray Observatory, in: The Second Compton Symposium, College Park, MD, 1993, AIP Conference Proceedings 304, eds. ... Rev. C 24 (1981) 335. [201 TN Taddeucci et al., Nucl. Phys. A 469 (1987) 125. ...
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