5264186
First investigation of excited states in the odd-proton nucleus 209 Fr
Excited states in {sup 209}Fr were produced following the {sup 176}Yb({sup 37}Cl, 4n) reaction. An excitation function was measured with data taken at 173, 179, and 185 MeV. Recoiling fusion-evaporation products were separated using the SASSYER gas-filled spectrometer. HPGe clover detectors of the YRAST Ball array at the target position and at the focal plane were used to detect prompt and delayed gamma ray decays, providing the first spectroscopic information about prompt and delayed transitions in {sup 209}Fr. The decay from a proposed {pi}i{sub 13/2} configuration isomer was observed in {sup 209}Fr, and its half-life was measured to be 446(14)ns. States above the isomer were also observed.
14509196
Enhanced mixing of intrinsic states in deformed Hf nuclei
Excited low-spin, nonyrast states in {sup 170,172,174}Hf were populated in {beta}{sup +}/{epsilon} decay and studied through off-beam {gamma}-ray spectroscopy. New coincidence data allowed for a substantial revision of the level schemes of {sup 170,172}Hf and a confirmation of the level scheme of {sup 174}Hf. The Hf isotopes represent a unique situation in which a crossing of collective intrinsic excitations occurs, enhancing significantly the effects of mixing. Using branching ratios from excited 2{sup +} states, this mixing is followed and studied. The resulting mixing matrix elements are found to be {approx}30 keV - an order of magnitude larger than estimated previously for nearby nuclei. In the case of {sup 170}Hf, the 2{sub {beta}}{sup +} and 2{sub {gamma}}{sup +} level are shown to be completely mixed.
17355738
Extensive investigation of 0+ states in rare earth region nuclei
The nature of 0{sup +} excitations, especially in transitional and deformed nuclei, has attracted new attention. Following a recent experiment studying {sup 158}Gd, we investigated a large group of nuclei in the rare-earth region with the (p,t) pickup reaction using the Q3D magnetic spectrograph at the University of Munich MP tandem accelerator laboratory. Outgoing tritons were recorded at various lab angles, and their angular distributions are compared to those calculated using the distorted-wave Born approximation. Using the unique shape of the L=0 angular distribution, more than double the number of 0{sup +} states than were previously known are identified. The distribution of 0{sup +} energies and cross sections is discussed in terms of collective and noncollective degrees of freedom, and the density of low-lying 0{sup +} states is discussed as a corroboration of a characteristic feature of phase transition regions. The degree of level mixing, as extracted from Brody distribution fits to the energy spacings of adjacent 0{sup +} levels, is also explored.
121160071
Evidence for the microscopic formation of mixed-symmetry states from magnetic moment measurements
Using the transient field technique, the magnetic moments of the second excited 2{sup +} states in {sup 92,94}Zr have been measured for the first time. The large positive g factors, g(2{sub 2}{sup +};{sup 92}Zr)=+0.76(50) and g(2{sub 2}{sup +};{sup 94}Zr)=+0.88(27), which are in contrast to the known negative g factors of the 2{sub 1}{sup +} states, are found to be a consequence of weak proton-neutron coupling combined with the Z=40 subshell closure. From their large M1 transition strengths to the 2{sub 1}{sup +} states, in earlier works an assignment to the 2{sub 2}{sup +} states as proton-neutron symmetric and mixed-symmetry states has been made, which are now found to be polarized in their proton-neutron content. This fact allows to identify the underlying microscopic main configurations in the wave functions, which form the building blocks of symmetric and mixed-symmetry states in this region as valence nucleons are added and shell structure changes.
17884247
Performance of the LHCb RICH detector at the LHC
The LHCb experiment has been taking data at the Large Hadron Collider (LHC) at CERN since the end of 2009. One of its key detector components is the Ring-Imaging Cherenkov (RICH) system. This provides charged particle identification over a wide momentum range, from 2–100 GeV/c. The operation and control, software, and online monitoring of the RICH system are described. The particle identification performance is presented, as measured using data from the LHC. Excellent separation of hadronic particle types (π, K, p) is achieved.
120723671
A measurement of the $CP$-violating phase $\phi{_s}$ in the decay $B{^0_s} \to J/\psi\phi$
118155679
Charmonium and Heavy Flavour Production at LHCb
The underlying mechanism of prompt charmonium production at hadron colliders is a topic of great interest. Measurements of charmonium production at at the Large Hadron Collider beauty (LHCb) experiment for both prompt and secondary J=y(1S) events will be compared with theoretical expectation. Results will also be shown for other charmonium states, and for the upsilon system. The LHCb physics programme relies on the reconstruction of the decays of B and D hadrons. An important first step in this program is to demonstrate that this reconstruction can be done with high efficiency, and to establish the production cross-section for these hadrons in pp collisions at p s = 7 TeV, which is presented here.