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We have measured the cross section of the $^{83}$Rb(p,$γ)^{84}$Sr radiative capture reaction in inverse kinematics using a radioactive beam of $^{83}$Rb at incident energies of 2.4 and $2.7 A$ MeV. Prior to the radioactive beam measurement, the $^{84}$Kr(p,$γ)^{85}$Rb radiative capture reaction was measured in inverse kinematics using a stable beam of $^{84}$Kr at an incident energy of $2.7 A$ MeV. The effective relative kinetic energies of these measurements lie within the relevant energy window for the $γ$ process in supernovae. The central values of the measured partial cross sections of both reactions were found to be $0.17-0.42$ times the predictions of statistical model calculations. Assuming the predicted cross section at other energies is reduced by the same factor leads to a slightly higher calculated abundance of the $p$ nucleus $^{84}$Sr, caused by the reduced rate of the $^{84}$Sr($γ$,p)$^{83}$Rb reaction derived from the present measurement., 11 pages, 11 figures. arXiv admin note: text overlap with arXiv:2109.06775

The selenium isotopes lie at the heart of a tumultuous region of the nuclear chart where shape coexistence effects grapple with neutron-proton pairing correlations, triaxiality, and the impending proton dripline. In this work a study of $^{72}$Se by internal conversion electron and $\gamma$-ray spectroscopy was undertaken with the SPICE and TIGRESS arrays. New measurements of the branching ratio and lifetime of the $0_2^+$ state were performed yielding a determination of $\rho^2(E0;0_2^+{\rightarrow}0_1^+)=29(3)$ milliunits. two state mixing calculations were performed that highlighted the importance of interpretation of such $E0$ strength values in the context of shape-coexistence.

We present new experimental measurements of resonance strengths in the astrophysical 23Al(p, {\gamma})24Si reaction, constraining the pathway of nucleosynthesis beyond 22Mg in X-ray burster scenarios. Specifically, we have performed the first measurement of the (d, p) reaction using a radioactive beam of 23Ne to explore levels in 24Ne, the mirror analog of 24Si. Four strong single-particle states were observed and corresponding neutron spectroscopic factors were extracted with a precision of {\sim}20{\%}. Using these spectroscopic factors, together with mirror state identifications, we have reduced uncertainties in the strength of the key {\ell} = 0 resonance at Er= 157 keV, in the astrophysical 23Al(p, {\gamma}) reaction, by a factor of 4. Our results show that the 22Mg(p, {\gamma})23Al(p, {\gamma}) pathway dominates over the competing 22Mg({\alpha}, p) reaction in all but the most energetic X-ray burster events (T>0.85GK), significantly affecting energy production and the preservation of hydrogen fuel., Comment: 5 pages, 3 figures

Reactions on the proton-rich nuclides drive the nucleosynthesis in Core-Collapse Supernovae (CCSNe) and in X-ray bursts (XRBs). CCSNe eject the nucleosynthesis products to the interstellar medium and hence are a potential inventory of p-nuclei, whereas in XRBs nucleosynthesis powers the light curves. In both astrophysical sites the Ni-Cu cycle, which features a competition between $^{59}$Cu(p,$��$)$^{56}$Ni and $^{59}$Cu(p,$��$)$^{60}$Zn, could potentially halt the production of heavier elements. Here, we report the first direct measurement of $^{59}$Cu(p,$��$)$^{56}$Ni using a re-accelerated $^{59}$Cu beam and cryogenic solid hydrogen target. Our results show that the reaction proceeds predominantly to the ground state of $^{56}$Ni and the experimental rate has been found to be lower than Hauser-Feshbach-based statistical predictions. New results hint that the $��p$-process could operate at higher temperatures than previously inferred and therefore remains a viable site for synthesizing the heavier elements.

The $��$-decay of neutron-rich $^{129}$In into $^{129}$Sn was studied using the GRIFFIN spectrometer at the ISAC facility at TRIUMF. The study observed the half-lives of the ground state and each of the $��$-decaying isomers. The level scheme of $^{129}$Sn has been expanded with thirty-one new $��$-ray transitions and nine new excited levels, leading to a re-evaluation of the $��$-branching ratios and level spin assignments. The observation of the $��$-decay of the (29/2$^{+}$) 1911-keV isomeric state in $^{129}$In is reported for the first time, with a branching ratio of 2.0(5)$\%$.

Background: Recent developments in {\it ab initio} nuclear theory demonstrate promising results in medium- to heavy-mass nuclei. A particular challenge for many of the many-body methodologies, however, is an accurate treatment of the electric-quadrupole, $E2$, strength associated with collectivity. Purpose: In this work we present high-precision $E2$ data for the mirror nuclei $^{23}$Mg and $^{23}$Na for comparison with such theory. We interpret these results in combination with other recent measurements performed by the collaboration and the available literature. Methods: Coulomb-excitation measurements of $^{23}$Mg and $^{23}$Na were performed at the TRIUMF-ISAC facility using the TIGRESS spectrometer and were used to determine the $E2$ matrix elements of mixed $E2$/$M1$ transitions. Results: $E2$ transition strengths were extracted for $^{23}$Mg and $^{23}$Na. Transition strength ($B(E2)$) precision was improved by factors of approximately six for both isotopes, while agreeing within uncertainties with previous measurements. Conclusions: A comparison was made with both shell-model and {\it ab initio} valence-space in-medium similarity renormalization group calculations. Valence-Space In-Medium Similarity-Renormalization-Group calculations were found to underpredict the absolute $E2$ strength - in agreement with previous results - but a full analysis of $sd$-shell nuclei found no indication of an isovector component to the missing strength. Comparison with full configuration interaction and coupled cluster calculations in the case of $^{14}$C indicates that correlated multi-particle multi-hole excitations are essential to the reproduction of quadrupole excitation amplitudes., To be submitted to Physical Review C

The low-lying structure of semi-magic $^{118}$Sn has been investigated through the $��$-decay of $^{118}$In ($T_{1/2}=4.45$ min) to study shape coexistence via the reduced transition probabilities of states in the 2p-2h proton intruder band. This high-statistics study was carried out at TRIUMF-ISAC with the GRIFFIN spectrometer. In total, 99 transitions have been placed in the level scheme with 43 being newly observed. Three low-lying $��$-ray transitions with energies near 285 keV have been resolved from which the 2$^+_{\mathrm{intr.}} \rightarrow 0^+_{\mathrm{intr.}}$ 284.52-keV transition was determined to have half of the previous branching fraction leading to a $B(E2;2^+_2\rightarrow 0^+_2)$ of 21(4) W.u. compared to 39(7) W.u. from the previous measurement. Calculations using $sd$ IBM-2 with mixing have also been made to compare the experimental $B(E2)$ values to the theoretical values and to make comparisons to the $^{114,116}$Sn isotopes previously studied using the same theoretical model.

Spectroscopy of doubly magic $^{132}_{50}$Sn$_{82}$ has been performed with the GRIFFIN spectrometer at TRIUMF-ISAC following the $��$ decay of $^{132}_{49}$In$_{83}$. The analysis has allowed for the placement of a total of 70 transitions and 29 excited states in $^{132}$Sn. Detailed spectroscopy has also been performed on $^{131}$Sb, resulting from the $��$ decay of $^{131}$Sn, produced from the $��$-delayed neutron decay of $^{132}$In. Measurement of $��$-rays in both $^{131}$Sn and $^{131}$Sb has led to the determination of the $��$-delayed neutron emission probability, $P_{n}$, from $^{132}$In. This is the first time the $P_{n}$ has been measured for this nucleus using $��$ spectroscopy, and the new value of 12.3(4)% is consistent with the most recent $��-n$ counting experiment. Additionally, $��$-$��$ angular correlations have been performed in $^{132}$Sn, supporting the spin assignments of several excited states. Novel ab initio calculations are presented which describe several of the excited states, and these are compared to the experimental spectrum., 14 pages, 7 figures, to be published in Physical Review C

The $��^-$ decay of $^{47}$K to $^{47}$Ca is an appropriate mechanism for benchmarking interactions spanning the $sd$ and $pf$ shells, but current knowledge of the $��^-$-decay scheme is limited. We have performed a high-resolution, high-efficiency study of the $��^-$-decay of $^{47}$K with the GRIFFIN spectrometer at TRIUMF-ISAC. The study revealed 48 new transitions, a more precise value for the $^{47}$K half-life (17.38(3)~s), and new spin and parity assignments for eight excited states. Levels placed for the first time here raise the highest state observed in $��^-$ decay to within 568(3) keV of the $Q$-value and confirm the previously measured large $��^-$-decay branching ratios to the low-lying states. Previously unobserved $��^-$-feeding to 3/2$^+$ states between 4.5 and 6.1~MeV excitation energy was identified with a total $��^-$-feeding intensity of 1.29(2)\%. The sum of the $B(GT)$ values for these states indicates that the $1s_{1/2}$ proton hole strength near this excitation energy is comparable to the previously known $1s_{1/2}$ proton and neutron hole strengths near 2.6 MeV.

A high-precision branching ratio measurement for the superallowed Fermi $��^{+}$ emitter $^{62}$Ga was performed with the Gamma-Ray Infrastructure for Fundamental Investigations of Nuclei (GRIFFIN) spectrometer at the Isotope Separator and Accelerator (ISAC) radioactive ion beam facility at TRIUMF. The high efficiency of the GRIFFIN spectrometer allowed 63 $��$-ray transitions, with intensities down to $\approx$1 part per million (ppm) per $^{62}$Ga $��^{+}$ decay, to be placed in the level scheme of the daughter nucleus $^{62}$Zn, establishing the superallowed $��$ branching ratio for $^{62}$Ga decay to be 99.8577$^{+0.0023}_{-0.0029}\%$, a factor of 4 more precise than the previous world average. For several cascades, $��-��$ angular correlation measurements were performed to assign spins and/or determine the mixing ratios of transitions. In particular, the spin of the 2.342 MeV excited state in the daughter nucleus $^{62}$Zn was definitively assigned as $J = 0$. This assignment resolves a discrepancy between previous measurements and has important implications for the isospin symmetry breaking correction, $��_{C1}$, in $^{62}$Ga superallowed Fermi $��$ decay., A text label in Figure 12 has been corrected compared to the original submission

The half-lives of three $��$ decaying states of $^{131}_{~49}$In$_{82}$ have been measured with the GRIFFIN $��$-ray spectrometer at the TRIUMF-ISAC facility to be $T_{1/2}(1/2^-)=328(15)$~ms, $T_{1/2}(9/2^+)=265(8)$~ms, and $T_{1/2}(21/2^+)=323(55)$~ms, respectively. The first observation of $��$-rays following the $��n$ decay of $^{131}$In into $^{130}$Sn is reported. The $��$-delayed neutron emission probability is determined to be $P_{1n} = 12(7)\%$ for the $21/2^+$ state and $2.3(3)\%$ from the combined $1/2^-$ and $9/2^+$ states of $^{131}_{~49}$In$_{82}$ observed in this experiment. A significant expansion of the decay scheme of $^{131}$In, including 17 new excited states and 34 new $��$-ray transitions in $^{131}_{~50}$Sn$_{81}$ is also reported. This leads to large changes in the deduced $��$ branching ratios to some of the low-lying states of $^{131}$Sn compared to previous work with implications for the strength of the first-forbidden $��$ transitions in the vicinity of doubly-magic $^{132}_{~50}$Sn$_{82}$., 14 pages, 15 figures, 5 tables

We report on high-statistics data from the $��^-$ decay of the $^{46}$K $J^��$ = 2$^-$ ground state taken with the GRIFFIN spectrometer located at the TRIUMF-ISAC facility. In total, 199 $��$ rays and 42 excited states were placed in the level scheme, and from the observed $��$ feeding and angular correlations of pairs of cascading $��$ rays, it was possible to assign spins and parities to excited states and determine mixing ratios for selected $��$ rays. The level structure of $^{46}$Ca is compared to theoretical predictions from a microscopic valence-space Hamiltonian derived from two- (NN) and three-nucleon (3N) forces. These calculations are in reasonable agreement with the experimental data and indicate that the protons in this region are not as inert as would be expected for semi-magic nuclei.

The half-lives of isotopes around the $N=82$ shell closure are an important ingredient in astrophysical simulations and strongly influence the magnitude of the second $r$-process abundance peak in the $A\sim130$ region. The most neutron-rich $N=82$ nuclei are not accessible to the current generation of radioactive beam facilities and $r$-process simulations must therefore rely on calculations of the half-lives of the isotopes involved. Half-life measurements of the experimentally accessible nuclei in this region are important in order to benchmark these calculations. The half-life of $^{130}$Cd is particularly important as it is used to tune the Gamow-Teller quenching in shell-model calculations for the $\beta$ decay of other nuclei in this region. In this work, the GRIFFIN $\gamma$-ray spectrometer at the TRIUMF-ISAC facility was used to measure the half-life of $^{130}_{~48}$Cd$_{82}$ to be $T_{1/2}= 126(4)$ ms. In addition, the half-lives of the three $\beta$ decaying states of $^{131}_{~49}$In$_{82}$ were measured to be $T_{1/2}(1/2^-)=328(15)$ ms, $T_{1/2}(9/2^+)=265(8)$ ms, and $T_{1/2}(21/2^+)=323(50)$ ms, respectively, providing an important benchmark for half-life calculations in this region., Comment: Talk presented CIPANP2018. 9 pages, LaTeX, 5 pdf figures, 1 png figure

The evolution of nuclear magic numbers at extremes of isospin is a topic at the forefront of contemporary nuclear physics. $N=50$ is a prime example, with increasing experimental data coming to light on potentially doubly-magic $^{100}$Sn and $^{78}$Ni at the proton-rich and proton-deficient extremes, respectively. Experimental discrepancies exist in the data for less exotic systems. In $^{86}$Kr the $B(E2;2^+_1\rightarrow0^+_1)$ value - a key indicator of shell evolution - has been experimentally determined by two different methodologies, with the results deviating by $3\sigma$. Here, we report on a new high-precision measurement of this value, as well as the first measured lifetimes and hence transition strengths for the $2^+_2$ and $3^-_{(2)}$ states in the nucleus. The Doppler-shift attenuation method was implemented using the TIGRESS gamma-ray spectrometer and TIGRESS integrated plunger (TIP) device. High-statistics Monte-Carlo simulations were utilized to extract lifetimes in accordance with state-of-the-art methodologies. Lifetimes of $\tau(2^+_1)=336\pm4\text{(stat.)}\pm20\text{(sys.)}$ fs, $\tau(2^+_2)=263\pm9\text{(stat.)}\pm19\text{(sys.)}$ fs and $\tau(3^-_{(2)})=73\pm6\text{(stat.)}\pm32\text{(sys.)}$ fs were extracted. This yields a transition strength for the first-excited state of $B(E2;2^+_1\rightarrow0^+)=259\pm3\text{(stat.)}\pm16\text{(sys.)}$ e$^2$fm$^4$. The measured lifetime disagrees with the previous Doppler-shift attenuation method measurement by more than $3\sigma$, while agreeing well with a previous value extracted from Coulomb excitation. The newly extracted $B(E2;2^+_1\rightarrow0^+_1)$ value indicates a more sudden reduction in collectivity in the $N=50$ isotones approaching $Z=40$., Comment: 17 pages, 10 figures, to be submitted to Physical Review C

The $T_z$~=~$-\frac{3}{2}$ nucleus ${}^{21}$Mg has been studied by Coulomb excitation on ${}^{196}$Pt and ${}^{110}$Pd targets. A 205.6(1)-keV $\gamma$-ray transition resulting from the Coulomb excitation of the $\frac{5}{2}^+$ ground state to the first excited $\frac{1}{2}^+$ state in ${}^{21}$Mg was observed for the first time. Coulomb excitation cross-section measurements with both targets and a measurement of the half-life of the $\frac{1}{2}^+$ state yield an adopted value of $B(E2;\frac{5}{2}^+\rightarrow\frac{1}{2}^+)$~=~13.3(4)~W.u. A new excited state at 1672(1)~keV with tentative $\frac{9}{2}^+$ assignment was also identified in ${}^{21}$Mg. This work demonstrates large difference of the $B(E2;\frac{5}{2}^+\rightarrow\frac{1}{2}^+)$ values between $T$~=~$\frac{3}{2}$, $A$~=~21 mirror nuclei. The difference is investigated in the shell-model framework employing both isospin conserving and breaking USD interactions and using modern \textsl{ab initio} nuclear structure calculations, which have recently become applicable in the $sd$ shell., Comment: 8 pages, 6 figures, submitted to Phys. Rev. C, Rapid Communication

A previous measurement of the $\beta-\gamma$ directional coefficient in $^{22}$Na $\beta$ decay was used to extract recoil-order form factors. The data indicate the requirement of a significant induced-tensor matrix element for the decay.This conclusion largely relies on a Standard-Model-allowed weak magnetism form factor which was determined using an unpublished value of the analog $2_1^+\to3_1^+$ $\gamma$ branch in $^{22}$Na, with the further assumption that the transition is dominated by its isovector $M1$ component. We obtain for the first time an unambiguous determination of the $2_1^+ \to 3_1^+$ branch in $^{22}$Na to be $0.45(8)\%$. Using the Conserved Vector Current (CVC) hypothesis, our branch determines the weak magnetism form factor for $^{22}$Na $\beta$ decay to be $|b/Ac_1| = 8.7(1.1)$. Together with the $\beta-\gamma$ angular correlation coefficient, we obtain a large induced-tensor form factor for the decay that continues to disagree with theoretical predictions. Two plausible explanations are suggested., Comment: Submitted to Phys. Rev. C

A high-precision half-life measurement for the superallowed Fermi $��^+$ emitter $^{22}$Mg was performed at the TRIUMF-ISAC facility using a 4$��$ proportional gas counter. The result of $T_{1/2} = 3.87400 \pm 0.00079$ s is a factor of 3 more precise than the previously adopted world average and resolves a discrepancy between the two previously published $^{22}$Mg half-life measurements., 7 pages, 9 figures

A $^{52}$Cr$(p,t)$$^{50}$Cr two-neutron pickup reaction was performed using the Q3D magnetic spectrograph at the Maier-Leibnitz-Laboratorium in Garching, Germany. Excited states in $^{50}$Cr were observed up to an excitation energy of 5.3 MeV. Despite significantly increased sensitivity and resolution over previous work, no evidence of the previously assigned first excited $0^+$ state was found. As a result, the $0^+_2$ state is reassigned at an excitation energy of $E_x=3895.0(5)$ keV in $^{50}$Cr. This reassignment directly impacts direct searches for a non-analogue Fermi $��^+$ decay branch in $^{50}$Mn. These results also show better systematic agreement with the theoretical predictions for the $0^+$ state spectrum in $^{50}$Cr using the same formalism as the isospin-symmetry-breaking correction calculations for superallowed nuclei. The experimental data are also compared to $ab$-$initio$ shell-model predictions using the IM-SRG formalism based on $NN$ and $3N$ forces from chiral-EFT in the $pf$-shell for the first time., Accepted for Publication in Physical Review C as a Rapid Communication

Objective: Duplex scanning may be used to detect high-grade stenoses in the mesenteric vessels in patients with suspect Chronic Mesenterial Ischemia (CMI). The aim of the study was to evaluate reserve and collateral vascular function in relation to bowel symptoms in patients with CMI. Methods: Fourteen consecutive patients, referred to the vascular laboratory with suspicion of CMI, 7 men (average 79 years), and 7 women (average 66 years), were investigated by Duplex ultrasound (DUS) of the visceral arteries. All patients were examined both fasting and 30 min after a standard meal. A reference group of 10 patients with diffuse bowel symptoms (5 men and 5 women, (average 75 years) were investigated by the same DUS protocol, all showing normal mesenteric arteries. Possible collateral reserve capacity was defined as a marked increase of flow velocities (>20%) in vessels with lesions and/or in non-affected vessels. Results: All patients had a significant stenosis (>70%) in one or several visceral arteries at the baseline DUS investigation. Six patients had abdominal pain after the test meal, whilst 8 patients experienced no pain. In patients without postprandial pain a possible collateral reserve capacity was detected. In this group superior mesenteric artery (SMA) peak systolic velocity (PSV) increased significantly (baseline PSV 2.6 ± 1.3 m/s vs. postprandial PSV 4.1 ± 1.6 m/s, P < 0.05) whereas patients with postprandial pain showed no signs of collateral reserve capacity in any vessel except one patient who showed possible collateral reserve in one vessel. In the reference group a significant increase of PSV was seen in SMA only, (1.7 ± 0.6, vs. 2.5 ± 0.9, P < 0.05). Conclusion: Postprandial duplex adds information about the functional flow limitation of the stenosis and possible collateral reserve flow capacity. Further studies have to be performed to establish criteria for selection of patients appropriate for intervention.

We report a precise determination of the 19Ne half-life to be $T_{1/2} = 17.262 \pm 0.007$ s. This result disagrees with the most recent precision measurements and is important for placing bounds on predicted right-handed interactions that are absent in the current Standard Model. We are able to identify and disentangle two competing systematic effects that influence the accuracy of such measurements. Our findings prompt a reassessment of results from previous high-precision lifetime measurements that used similar equipment and methods., Comment: 5 pages and 5 figures. Paper accepted for publication in Phys. Rev. Lett

Interviews were carried out with 423 women and 93 men with invasive or in situ anal cancer in Denmark and Sweden in a search for clues to the aetiology of this neoplasm. Patients with rectal adenocarcinoma (n = 534) and persons drawn from the background population (n = 554) served as controls. Multivariate logistic regression analyses confirmed previous observations of a strong association between either male homosexual experience or a history of anogenital warts and the risk for anal cancer. Moreover, hitherto unknown, but strong and consistent associations were observed between measures of high heterosexual activity and the risk for anal cancer among both sexes. Polymerase chain reaction analysis revealed human papilloma-virus DNA in the majority (88%) of anal cancer specimens but in none of 20 examined rectal adenocarcinomas. It is concluded that most anal cancers appear to be caused by sexually transmitted types of human papillomaviruses and, consequently, that anal cancer is a potentially preventable neoplasm.

Excited states in 52Fe have been determined up to spin 10\hbar in the reaction 28Si + 28Si at 115 MeV by using \gamma-ray spectroscopy methods at the GASP array. The excitation energy of the yrast 10+ state has been determined to be 7.381 MeV, almost 0.5 MeV above the well known \beta+-decaying yrast 12+ state, definitely confirming the nature of its isomeric character. The mean lifetimes of the states have been measured by using the Doppler Shift Attenuation method. The experimental data are compared with spherical shell model calculations in the full pf-shell., Comment: 9 pages, RevTeX, 7 figures included

The rate of tension development following release of ATP from caged-ATP in the presence of calcium was studied in skinned cardiac fibres from swine. A low-force rigor state was obtained by using butanedione monoxime (BDM) during the induction of rigor. BDM was washed out and following release of ATP in the presence of Ca2+ (pCa 4.3), the muscles contracted with an apparent rate of about 2 s-1 at 22 degrees C. After treatment with 10 mM vanadate to extract troponins I and C the fibres contracted independently of calcium. The rate of contraction upon release of ATP was slower than prior to extraction and was independent of [Ca2+]. Since treatment with vanadate has been shown to extract about 90% of troponin-I the results suggest that the muscles under these conditions are partially activated by removal of an inhibition of cross-bridge interaction by troponin I. A partial recovery of force was obtained by prolonged incubation in DTT containing solutions possibly reflecting reconstitution with troponin I still present in the fibre bundle. Treatment with a solution containing whole troponin caused almost complete recovery of calcium sensitivity and rate of force development. The calcium sensitizer EMD 53998 increased rates of contraction in a dose dependent manner, suggesting that this compound increases force and calcium sensitivity by increasing the cross-bridge attachment rates.

We here report the spontaneous loss of both homologues of the c-jun gene in two cell lines, isolated after transfection of rat embryo fibroblasts with single ras-oncogenes. These cells lines (designated A14 and B25) grow rapidly in vitro, have transformed morphologies and are invasive through reconstituted basal membranes. Both c-jun defective cell lines were found to be tumorigenic and metastatic in athymic mice. Loss of c-jun was paralleled by a dramatic decrease in interstitial collagenase expression, whereas stromelysin mRNA expression in c-jun- A14 and B25 cells was similar to that observed in c-jun+ transformed cell lines. Transient transfection experiments using reporter plasmids showed that stromelysin promoter activity in A14 cells was severely impaired by a point mutation in the -71 to -65 AP-1 motif, and was inhibited by a Jun dominant negative mutant. Gel mobility shift studies demonstrated the presence of a factor in A14 nuclear extracts capable of binding the stromelysin TRE. This factor bound JunB, JunD and Fos antibodies. Our findings suggest that c-Jun is not required for the tumorigenic and metastatic potential of ras-transformed fibrosarcoma cells, and that AP-1 protein(s) lacking c-Jun are capable of activating the stromelysin gene promoter.

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γ decays from high-spin states in the N=Z-1 nucleus 2753Co26 have been identified for the first time. Level energies and Coulomb energy differences between these states and their analogs in its mirror nucleus 53Fe have been compared with large-scale pf shell-model calculations, which offer excellent agreement. New information has been obtained on two-proton Coulomb matrix elements needed in the interpretation. These have been extracted from the data via a number of methods and are shown to exhibit an anomalous behavior for the J = 2 coupling.

Three examples of recent nuclear structure studies using Gammasphere are discussed in this paper. (1) A rotational band has been identified in 108Cd. Its moment of inertia and quadrupole moment indicate that this band has a shape with an axis ratio larger than 1.8:1. (2) Possible "Jacobi" shape transitions at high spin were investigated from studies of the continuum gamma rays on a number of nuclei. (3) Population of high-spin states in neutron-rich nuclei were studied in target fragmentation reactions. States with spin up to 6-12 were observed in a wide range of nuclei.

High-spin states in 3676Kr40 have been populated in the 40Ca(40Ca,4p)76Kr fusion-evaporation reaction at a beam energy of 165 MeV, and studied using the GAMMASPHERE and MICROBALL multi-detector arrays. The ground-state band and two signature-split negative-parity bands of 76Kr have been extended to ∼30hℏ. Lifetime measurements using the Doppler-shift attenuation method indicate that the transition quadrupole moment of these three bands decrease as they approach their maximum-spin states.