The deep-sea bottom longline fishery targeting Dissostichus eleginoides is presently expanding everywhere in the Indian sector of the subantarctic part of the Southern Ocean. By-catch occurs in the fishery but is rarely reported because fish are often discarded. The results of two joint Japanese-French exploratory fishing cruises conducted off the Kerguelen and the Crozet islands during 1996 and 1997 showed that by-catch reaches 35% of the total number of fish and nearly 13% of the weight. The grenadier Macrourus carinatus (Macrouridae) is the most common species and competes with the target species in a limited depth range. Rajidae (Raja taaf off Crozet and Bathyraja spp. off Kerguelen) and Moridae (Antimora rostrata) are secondary by-catch. The unreported catches contribute to a loss of information for stock assessment studies which reduces the opportunity to evaluate the impact of this fishing method on the deep-sea environment. Some of these species could be successfully marketed.

The Mg-25(d,He-3)Na-24 reaction has been investigated at 29 MeV incident energy. Spectra were measured at theta(lab)=10 degrees and 18 degrees. Observations using a split-pole magnetic spectrograph have been made of 56 levels of Na-24 in the range of excitation energy between 0 and 7.3 MeV. Most of these have been identified with Na-24 levels which have been previously observed by other techniques. From the ratios of the experimental as well as distorted-wave Born approximation (DWBA)-predicted cross sections at the two angles, the population through the pickup of an l(p)=1 proton has been established (or confirmed) for the twelve levels at E-x = 3.372, 3.745, 3.936, 4.524, 5.192, 5.250, 5.452, 5.846, 5.863, 6.905, 7.084, and 7.246 MeV. Spectroscopic factors were obtained from the comparison of the experimentally measured cross sections at the two angles with the DWBA-predicted cross sections, The experimental values of spectroscopic factors and excitation energies for positive-parity states were compared with the results of a recent, complete sri-shell space, shell-model calculation. In conjunction with the results of various previous works, this comparison leads to the identification of 19 shell-model levels with experimental levels, and thus allows the removal of ambiguities existing in the current literature for the J(pi) values of some Na-24 stares with E-x<3.7 MeV.

The reaction 15Na(α,γ)19F is of great importance for fluorine nucleosynthesis. At temperatures where 19F is expected to be produced, the narrow resonance associated with the 4.377 MeV level of 19F yields the dominant contribution to cross section. We have extracted its width by using the alpha‐transfer reaction 15N(7Li,t)19F and finite range DWBA analysis.

The Si-29(d, He-3)Al-28 reaction has been investigated at 29 MeV incident energy. Observations using a split-pole magnetic spectrograph have been made of 55 levels of Al-28 in the range of excitation energy between 0 and 6.7 MeV. Most of them have been identified with Al-28 levels which have been previously observed by other techniques. The spectroscopic factors have been obtained for 23 of these levels through distorted-wave Born approximation analyses of measured angular distributions. The levels at E(x)=3.105 and 3.762 MeV have been definitely assigned J(pi)=1+ and 0+, respectively. Four levels which are populated through the pickup of a l(p)=1 proton have been observed at E(x)=4.998, 5.406, 6.021, and 6.652 MeV. The excitation energies and spectroscopic factors for positive-parity states were compared with the results of a recent, complete sd-shell space, shell-model calculation. This comparison led to the identification of 21 shell-model levels with experimental levels. This comparison seems accurate enough to make very likely the J(pi)=3+ assignment for the levels at E(x)=2.988 and 4.597 MeV which were previously assigned J(pi)=(1,3)+.

The availability of a target of Hf-178 in its aligned four-quasiparticle, J(pi) = 16+ isomeric state, has allowed to measure the effect of blocking of the aligned-quasineutron orbitals in the (p, t) reaction. The experimental ratio of cross sections R = sigma(16+ --> 16+) /sigma(0+ --> 0+) agrees with a predicted value deduced from the known (p, t) cross section on odd Hf isotopes.

The γ-decay of the deeply-bound hole states in 111Sn has been investigated at 32 MeV incident energy by means of the 112Sn(3He, αγ) reaction. The α-particles emitted near 0° were detected in a Si counter located at the image plan of the superconducting solenoidal spectrometer SOLENO. The γ-rays in coincidence with the α-particles were detected by two Ge(Li) detectors located at 90° and 142° with respect to the beam direction, respectively. Energies, spins and decay schemes have been established for the low-lying states up to 2.5 MeV excitation energy in 111Sn. The γ-decay of the broad bump, located around 4.2 MeV and previously attributed to neutron pick-up from the inner 1g92, 2p12, and 2p32 neutron. Subshells, reveals the importance of quasiparticle-phonon m the spreading mechanism of the inner-hole strengths. The 1g92 and 2p strength functions have been deduced from the α-decay of the enhanced structures (3 ≦ Ex≦ 8 MeV). They are compared to the ones measured in previous inclusive neutron pick-up experiments and to those calculated in the framework of the quasiparticle-phonon nuclear model.

Important breakings of the multi-$j$ $\mathrm{U}(\frac{6}{12})$ supersymmetry schemes have been observed in the $^{195}\mathrm{Pt}$(d,p)$^{196}\mathrm{Pt}$ reaction. Including only in the analysis the known levels with $J<4$ below 1.5 MeV excitation energy, it appears that an appreciable fraction, 36%, of the total observed strength corresponds to transitions to the ${2}_{2}^{+}$, ${0}_{2}^{+}$, and ${0}_{3}^{+}$ levels, forbidden in the $\mathrm{U}(\frac{6}{12})$ scheme but experimentally observed with 19%, 21%, and 36% of the strength of the allowed transition to the ground state.

The projected ranges, angular distributions and range distributions at each laboratory angle have been measured for one-, two-, and three-proton transfer reactions induced in $^{209}\mathrm{Bi}$ by various heavy ions from $^{14}\mathrm{N}$ to $^{63}\mathrm{Cu}$. The products observed were $^{210}\mathrm{Po}$, $^{211}\mathrm{At}$, and $^{211}\mathrm{Rn}$. They were identified by their radioactive decay characteristics. Some complementary experiments have been performed using T1 and Au targets. The angular and energy distributions have been used to identify the most probable reaction paths leading to the observed isotopes. At low incident energy, these reaction paths appear to be those which correspond to the most favorable energetics, for all incident ions. At higher energies, more complex reaction channels have a significant contribution to the production of the observed isotopes. For all incident ions, the position of the angular distribution maximum ${\ensuremath{\theta}}_{max}$ is governed by the value of the ratio $\frac{E}{B}$ of the incident energy to the interaction barrier. The variation of ${\ensuremath{\theta}}_{max}$ versus $\frac{E}{B}$ is very similar to that of the rainbow angle corresponding to elastic scattering. This might indicate that quasi-elastic transfer and rainbow scattering occur for similar distances of closest approach between colliding nuclei.NUCLEAR REACTIONS $^{209}\mathrm{Bi}$(HI,$x$)$^{210}\mathrm{Po}$, $^{211}\mathrm{At}$, $^{211}\mathrm{Rn}$, with HI=$^{14}\mathrm{N}$, $^{16}\mathrm{O}$, $^{19}\mathrm{F}$, $^{40}\mathrm{Ar}$, $^{40}\mathrm{Ca}$, $^{56}\mathrm{Fe}$, and $^{63}\mathrm{Cu}$. Measured $\ensuremath{\sigma}(\ensuremath{\theta})$, recoil ranges. Deduced most probable reaction path.

The excitation functions for the production of $^{210}\mathrm{Bi}$, $^{210}\mathrm{Po}$, $^{207\ensuremath{-}211}\mathrm{At}$, and $^{211}\mathrm{Rn}$ through quasielastic transfer reactions induced with heavy ions in $^{209}\mathrm{Bi}$ have been measured. The corresponding reactions involved the transfer of one neutron, one proton, two charges, and three charges from projectile to target. The projectiles used were $^{12}\mathrm{C}$, $^{14}\mathrm{N}$, $^{16}\mathrm{O}$, $^{19}\mathrm{F}$, $^{20}\mathrm{Ne}$, $^{40}\mathrm{Ar}$, $^{40}\mathrm{Ca}$, $^{56}\mathrm{Fe}$, and $^{63}\mathrm{Cu}$. The experimental techniques involved target irradiations and off-line $\ensuremath{\alpha}$ and $\ensuremath{\gamma}$ activity measurements. Chemical separations were used to solve specific problems. Careful measurements of incident energies and cross sections were performed close to the reaction thresholds. All excitation functions exhibit the typical features of quasielastic transfer reactions: a sharp increase at low energy, and a constant value at high incident energy. The position of the thresholds are strongly influenced by the energetics of the reaction: High cross sections are observed under the strong interaction barrier if the energy balance at the minimum distance of approach is positive. This balance is equal to the difference between the interaction potentials in the entrance and exit channels, corrected for the mass balance. The constant cross sections observed for the high energy part of a given excitation function are consistent with the assumption that the curve $P(R)$ which represents the transfer probability versus the distance between the nucleus centers does not vary with incident energy. This assumption implies the constancy of the optimum distance of approach ${R}_{\mathrm{opt}}$, of the $R$ window $\ensuremath{\Delta}R$ for which $P(R)$ is significant, and of the magnitude of $P(R)$. Moreover the data show that the high energy cross sections for one-proton transfer are independent of the projectile, while odd-even effects of the projectile atomic number $Z$ on the two-charge transfer cross sections are observed for the lightest incident ions $^{14}\mathrm{N}$ to $^{20}\mathrm{Ne}$.NUCLEAR REACTIONS $^{209}\mathrm{Bi}(\mathrm{HI}, X)$, $^{211,210,209,208,207}\mathrm{At}$, $^{211}\mathrm{Rn}$, with HI=$^{12}\mathrm{C}$, $^{14}\mathrm{N}$, $^{16}\mathrm{O}$, $^{19}\mathrm{F}$, $^{20}\mathrm{Ne}$, $^{40}\mathrm{Ar}$, $^{56}\mathrm{Fe}$, $^{63}\mathrm{Cu}$. $\frac{E}{A}\ensuremath{\simeq}4.5\ensuremath{-}10$ MeV/nucleon. Measured $\ensuremath{\sigma}(E)$.

The /sup 52/Cr(/sup 3/He, d)/sup 53/Mn reaction investigated at 25 MeV incident energy with a split pole spectrometer was used to populate highly excited analog states in /sup 53/Mn. Fifty-two levels between 6.9 and 12.0 MeV excitation energy were observed in /sup 53/Mn. The main components of the T/sub greater-than/2p/sub 3/2/, 2p/sub 1/2/, 1f/sub 5/2/, and 1g/sub 3/2/ single-particle strengths were identified. Angular distributions of transitions to 38 unbound levels in /sup 53/Mn have been extracted and analyzed with distorted-wave Born approximation and Gamov functions (as form factors for the transferred proton) to yield the absolute spectroscopic strength. An appreciable amount of the missing 2p/sub 3/2/, 2p/sub 1/2/, and 1f/sub 5/2/ proton T/sub less-than/ strengths is observed in /sup 53/Mn between 7.0 and 8.5 MeV whereas a small fraction of the 1g/sub 9/2/ and 2d/sub 5/2/ single-particle orbitals appears between 7.0 and 12 MeV excitation energy. The /sup 52/Cr(/sup 3/He, dp)/sup 52/Cr reaction was performed at 24 MeV incident energy using a triplet of magnetic quadrupole lenses. The angular correlations of the emitted protons were measured in coincidence using method II of Litherland and Ferguson with zero degree detection of deuteron groups. Spins, population parameters, and branching ratios of protonmore » partial widths to the ground and excited states of the target were determined for 14 unbound levels in /sup 53/Mn from the analysis of the angular correlation data. These two experiments provide a rather complete description of the spectroscopic properties of the analog of the levels of /sup 53/Cr up to 5.0 MeV excitation energy. A comparison is made with the previous (/sup 3/He, d), (p, ..gamma..), (p, p), and (d, p) results on the same target. Components of the /sup 53/Cr parent states which consist of a neutron coupled to an excited state of the /sup 52/Cr nucleus are also determined. (AIP)« less