We introduce a natural and simple way to implement the regularization scheme of the Hartree-Fock-Bogoliubov equations with zero range pairing interaction. The renormalization scheme proves to be equivalent to a simple energy cutoff with a position dependent running coupling constant.

Two-proton decays of ${}_{}{}^{12}{}_{}{}^{}O$ and ${}_{}{}^{16}{}_{}{}^{}N\mathrm{e}$ ground states are studied in a three-body model. We have found that the two-proton widths for the states should be much less than the existing experimental values (about 10 times for ${}_{}{}^{12}{}_{}{}^{}O$ and about 100 times for ${}_{}{}^{16}{}_{}{}^{}N\mathrm{e}$). We also have found that the structure of these states differs significantly from the mirror isobaric analog states (IAS): breaking of isobaric symmetry is at the level of tens of percents. Together with a corresponding decrease of the Coulomb energy, this effect can be considered as a three-body mechanism of the Thomas-Ehrman shift.

The excitation energy, spin, and parity of the yrast superdeformed band in ${}^{152}\mathrm{Dy}$ have been firmly established. The evidence comes mainly from the measured properties of a 4011 keV single-step transition connecting the yrast superdeformed level fed by the 693 keV transition to the ${27}^{-}$ yrast state. Four additional, weaker, linking $\gamma$ rays have been placed as well. The excitation energy of the lowest superdeformed band member is 10 644 keV and its spin and parity are determined to be ${24}^{+}$.

We present the first measurement of the pseudorapidity density of primary charged particles in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{}\mathrm{GeV}$. For the $6\%$ most central collisions, we obtain ${\mathrm{dN}}_{\mathrm{ch}}/d\eta {|}_{|\eta |<1\mathrm{}}=650\mathrm{}\pm 35\left(\mathrm{syst}\right)$. Compared to collisions at $\sqrt{s_{\mathrm{NN}}}=130\mathrm{}\mathrm{GeV}$, the highest energy studied previously, an increase by a factor of $1.14\pm 0.05$ at $90\%$ confidence level, is found. The energy dependence of the pseudorapidity density is discussed in comparison with data from proton-induced collisions and theoretical predictions.

A percolation model of nuclear fragmentation is used to interpret $10.2\mathrm{GeV}/c$ ${p+}^{197}\mathrm{Au}$ multifragmentation data. Emphasis is put on finding signatures of a continuous nuclear matter phase transition in finite nuclear systems. Based on model calculations, corrections accounting for physical constraints of the fragment detection and sequential decay processes are derived. Strong circumstantial evidence for a continuous phase transition is found, and the values of two critical exponents, $\sigma =0.5\mathrm{}\pm 0.1$ and $\tau =2.35\mathrm{}\pm 0.05$, are extracted from the data. A critical temperature of $T_c=8.3\mathrm{}\pm 0.2\mathrm{MeV}$ is found.

Transverse momentum spectra for charged hadrons and for neutral pions in the range $1\mathrm{GeV}/c<\mathrm{}{p}_T<5\mathrm{}\mathrm{GeV}/c$ have been measured by the PHENIX experiment at RHIC in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=130\mathrm{}\mathrm{GeV}$. At high $p_T$ the spectra from peripheral nuclear collisions are consistent with scaling the spectra from $p+p$ collisions by the average number of binary nucleon-nucleon collisions. The spectra from central collisions are significantly suppressed when compared to the binary-scaled $p+p$ expectation, and also when compared to similarly binary-scaled peripheral collisions, indicating a novel nuclear-medium effect in central nuclear collisions at RHIC energies.

New data are presented on the $p\left({e,e}^{\prime }p\right){\pi }^0$ reaction at threshold at a four-momentum transfer of $Q^2=0.05\mathrm{}{\mathrm{GeV}}^2{/c}^2$. The data were taken with the three-spectrometer setup of the A1 Collaboration at the Mainz Microtron MAMI. The complete center of mass solid angle was covered up to a center of mass energy of 4 MeV above threshold. Combined with measurements at three different values of the virtual photon polarization $\epsilon$, the structure functions ${\sigma }_T$, ${\sigma }_L$, ${\sigma }_{\mathrm{TT}}$, and ${\sigma }_{\mathrm{TL}}$ are determined. The results are compared with calculations in heavy baryon chiral perturbation theory and with a phenomenological model. The measured cross section is significantly smaller than both predictions.

The quality and intensity of $\gamma$ rays at the High Intensity $\gamma$-ray Source are shown to make nuclear resonance fluorescence studies possible at a new level of precision and efficiency. First experiments have been carried out using an intense $({10}^7\gamma /\mathrm{s})$ beam of $100\%$ linearly polarized, nearly monoenergetic, $\gamma$ rays on the semimagic nucleus ${}^{138}\mathrm{Ba}$. Negative parity quantum numbers have been assigned to 18 dipole excitations of ${}^{138}\mathrm{Ba}$ between 5.5 MeV and 6.5 MeV from azimuthal $\gamma$-intensity asymmetries.

The ratio of $L$- to $K$-shell electron captures in light nuclei is particularly sensitive to electron overlap and exchange effects. Calculations of these effects in ${}^7\mathrm{Be}$ disagree by more than $20\%$. We report a measurement of the $L/K$ ratio in ${}^7\mathrm{Be}$, using a cryogenic microcalorimeter which clearly separates $L$- and $K$-shell captures. The obtained $L/K$ ratio of 0.040(6) is less than half that of existing predictions for free ${}^7\mathrm{Be}$. The discrepancy is likely due to in-medium effects distorting the $L$-shell electron orbitals.

The assumption of simultaneous chemical and thermal freeze-outs of the hadron gas leads to a surprisingly accurate, albeit entirely conventional, explanation of the recently measured RHIC $p_{\perp }$ spectra. The original thermal spectra are supplied with secondaries from cascade decays of all resonances, and subsequently folded with a suitably parametrized expansion involving longitudinal and transverse flow. The predictions of this thermal approach, with various parametrizations for the expansion, are in a striking quantitative agreement with the data in the whole available range of $0\le p_{\perp }\le 3.5\mathrm{GeV}$.

The parity-violating longitudinal analyzing power, $A_z$, has been measured in $\overrightarrow{p}p$ elastic scattering at an incident proton energy of 221 MeV. The result obtained is $A_z=[0.84\pm 0.29(\mathrm{stat})\pm 0.17(\mathrm{syst}\left)\right]\times {10}^{-7\mathrm{}}$. This experiment is unique in that it selects a single parity violating transition amplitude ${(}^3{P}_2{}_{}{}^1{}_{}{}^{}-D_2^{}{}_{}{}^{})$ and consequently directly constrains the weak meson-nucleon coupling constant $h_{\rho }^{\mathrm{pp}}$. When this result is taken together with the existing $\overrightarrow{p}p$ parity violation data, the weak meson-nucleon coupling constants $h_{\rho }^{\mathrm{pp}}$ and $h_{\omega }^{\mathrm{pp}}$ can, for the first time, both be determined.

The first measurements of light antinucleus production in $\mathrm{Au}+\mathrm{Au}$ collisions at the Relativistic Heavy-Ion Collider are reported. The observed production rates for $\overline{d}$ and ${}^3\overline{\mathrm{He}}$ are much larger than in lower energy nucleus-nucleus collisions. A coalescence model analysis of the yields indicates that there is little or no increase in the antinucleon freeze-out volume compared to collisions at CERN SPS energy. These analyses also indicate that the ${}^3\overline{\mathrm{He}}$ freeze-out volume is smaller than the $\overline{d}$ freeze-out volume.

We report the first measurement of inclusive antiproton production at midrapidity in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=130\mathrm{GeV}$ by the STAR experiment at RHIC. The antiproton transverse mass distributions in the measured transverse momentum range of $0.25<\mathrm{}{p}_{\perp }<0.95\mathrm{GeV}/c$ are found to fall less steeply for more central collisions. The extrapolated antiproton rapidity density is found to scale approximately with the negative hadron multiplicity density.

We present the first precision measurement of the spin-dependent asymmetry in the threshold region of ${}^3\overrightarrow{\mathrm{H}}\mathrm{e}\left(\overrightarrow{e}{,e}^{\prime }\right)$ at $Q^2$ values of 0.1 and $0.2(\mathrm{GeV}/c{)}^2$. The agreement between the data and nonrelativistic Faddeev calculations which include both final-state interactions and meson-exchange current effects is very good at $Q^2=0.1\mathrm{}(\mathrm{GeV}/c{)}^2$, while a small discrepancy at $Q^2=0.2\mathrm{}(\mathrm{GeV}/c{)}^2$ is observed.

We present results for antilambda and antiproton production in $\mathrm{Au}+\mathrm{Au}$ collisions at $11.7A\mathrm{GeV}/c$ including spectra and extracted invariant yields for both species in central and peripheral collisions in the rapidity range $1.0<y<\mathrm{}1.4\mathrm{}$. The antilambda yield increases from ${\mathrm{dN}}_{\overline{\Lambda }}{/dy=1.2\mathrm{}}_{-0.6-0.2\mathrm{}}^{+0.7+0.2\mathrm{}}\times {10}^{-3\mathrm{}}$ in peripheral collisions to ${19}_{-5-2\mathrm{}}^{+4+3\mathrm{}}\times {10}^{-3\mathrm{}}$ in central collisions. The direct antiproton yield is deduced from the measured total antiproton spectra to extract the ratio of antilambda-to-direct-antiproton production. The $\overline{\Lambda }/\overline{p}$ ratio near midrapidity increases from ${0.26}_{-0.15-0.4\mathrm{}}^{+0.19+0.5\mathrm{}}$ in peripheral collisions to ${3.6}_{-1.8-1.1\mathrm{}}^{+4.7+2.7\mathrm{}}$ in central collisions, a value larger than current theoretical estimates.

The photon asymmetry in the reaction ${}^1\mathrm{H}(\overrightarrow{\gamma },{\pi }^0{)}^1\mathrm{H}$ close to threshold has been measured for the first time with the photon spectrometer TAPS using linearly polarized photons from the tagged-photon facility at the Mainz Microtron MAMI. The total and differential cross sections were also measured simultaneously with the photon asymmetry. This allowed determination of the $S$-wave and all three $P$-wave amplitudes. The values obtained at threshold are $E_{0+}=[-1.33\mathrm{}\pm 0.08(\mathrm{stat})\pm 0.03(\mathrm{syst}\left)\right]\times {10}^{-3\mathrm{}}{/m}_{{\pi }^{+}}$, $P_1=[9.47\pm 0.08(\mathrm{stat})\pm 0.29(\mathrm{syst}\left)\right]\times {10}^{-3\mathrm{}}{q/m}_{{\pi }^{+}}^2$, $P_2=[-9.46\mathrm{}\pm 0.1(\mathrm{stat})\pm 0.29(\mathrm{syst}\left)\right]\times {10}^{-3\mathrm{}}{q/m}_{{\pi }^{+}}^2$, and $P_3=[11.48\pm 0.06(\mathrm{stat})\pm 0.35(\mathrm{syst}\left)\right]\times {10}^{-3\mathrm{}}{q/m}_{{\pi }^{+}}^2$.

A rotational band with seven $\gamma$-ray transitions between states with spin $2ħ$ and $16ħ$ has been observed in the doubly magic, self-conjugate nucleus ${}_{20}^{40}{\mathrm{Ca}}_{20}$. The measured transition quadrupole moment of ${1.80}_{-0.29\mathrm{}}^{+0.39\mathrm{}}e\mathrm{b}$ indicates a superdeformed shape with a deformation ${\beta }_2{=0.59\mathrm{}}_{-0.07\mathrm{}}^{+0.11\mathrm{}}$. The features of this band are explained by cranked relativistic mean field calculations to arise from an 8-particle 8-hole excitation.

The transparency of carbon for $(p,2p)$ quasielastic events was measured at beam momenta ranging from 5.9 to $14.5\mathrm{GeV}/c$ at 90° c.m. The four-momentum transfer squared $\left(Q^2\right)$ ranged from 4.7 to $12.7(\mathrm{GeV}/c{)}^2$. We present the observed beam momentum dependence of the ratio of the carbon to hydrogen cross sections. We also apply a model for the nuclear momentum distribution of carbon to obtain the nuclear transparency. We find a sharp rise in transparency as the beam momentum is increased to $9\mathrm{GeV}/c$ and a reduction to approximately the Glauber level at higher energies.

The $\gamma$-ray decay of excited states of the two-proton hole nucleus, ${}^{206}\mathrm{Hg}$, has been identified using Gammasphere and ${}^{208}\mathrm{Pb}{+}^{238}\mathrm{U}$ collisions. The yrast states found include a $T_{1/2}=92\mathrm{}\left(8\right)\mathrm{ns}$ ${10}^{+}$ isomer located above the known $5^{-}$ isomer. The $B({E2;10\mathrm{}}^{+}\to 8^{+})$ strength is used to derive the quadrupole polarization charge induced by the $h_{11/2}$ proton hole. Also, the implied quadrupole moment has been used to provide an absolute scale for the electric field gradient of Hg in Hg metal.

A double-hyperfragment event has been found in a hybrid-emulsion experiment. It is identified uniquely as the sequential decay of ${}_{\Lambda \Lambda }^6\mathrm{He}$ emitted from a ${\Xi }^{-}$ hyperon nuclear capture at rest. The mass of ${}_{\Lambda \Lambda }^6\mathrm{He}$ and the $\Lambda -\Lambda$ interaction energy $\Delta B_{\Lambda \Lambda }$ have been measured for the first time devoid of the ambiguities due to the possibilities of excited states. The value of $\Delta B_{\Lambda \Lambda }$ is $1.01\pm {0.20}_{-0.11\mathrm{}}^{+0.18\mathrm{}}\mathrm{MeV}$. This demonstrates that the $\Lambda -\Lambda$ interaction is weakly attractive.