An Isolated Stellar-Mass Black Hole Detected Through Astrometric Microlensing

We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry of the source star of the long-duration (t_E ~ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462, in the direction of the Galactic bulge. HST imaging, conducted at eight epochs over an interval of six years, reveals a clear relativistic astrometric deflection of the background star's apparent position. Ground-based photometry shows a parallactic signature of the effect of the Earth's motion on the microlensing light curve. Combining the HST astrometry with the ground-based light curve and the derived parallax, we obtain a lens mass of 7.1 +/- 1.3 M_Sun and a distance of 1.58 +/- 0.18 kpc. We show that the lens emits no detectable light, which, along with having a mass higher than is possible for a white dwarf or neutron star, confirms its BH nature. Our analysis also provides an absolute proper motion for the BH. The proper motion is offset from the mean motion of Galactic-disk stars at similar distances by an amount corresponding to a transverse space velocity of ~45 km/s, suggesting that the BH received a modest natal 'kick' from its supernova explosion. Previous mass determinations for stellar-mass BHs have come from radial-velocity measurements of Galactic X-ray binaries, and from gravitational radiation emitted by merging BHs in binary systems in external galaxies. Our mass measurement is the first ever for an isolated stellar-mass BH using any technique

Survey of recent data on photon structure functions and resolved photon processes

Present data on the partonic content of the photon are reviewed. The results on the unpolarized structure functions from DIS experiments and on large p_T jet production processes in #gamma##gamma# and #gamma#p collisions are discussed for both real and virtual photons. A few related topics like the QED structure functions of the photon and the structure function of the electron are also shortly discussed. (orig.)Available from TIB Hannover: RA 2999(98-013) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Compensating calorimeters with inorganic active media for improved electron detection

In this paper we describe how compensating calorimeters can be modified to improve their resolution for electrons without degrading their energy resolution for hadrons. (orig.)Available from TIB Hannover: RA 2999(94-194) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Structure of excited states in nuclei near doubly magic "1"0"0SN

The three neutron-deficient nuclei "9"4Pd, "9"8Cd and "1"0"4Sn in the vicinity of "1"0"0Sn were investigated by means of in-beam #gamma#-ray spectroscopy of excited states. The isomeric decays in "9"4Pd and "9"8Cd were studied for the first time with an exclusive experimental setup for delayed #gamma#-ray detection with complete exit channel identification based on information from neutron and charged-particle filter detectors. The structure of excited states of "9"4Pd showed the first indication of increasing proton-neutron interaction towards the N=Z line in this region of nuclei, that in turn might be related to increased proton-neutron pairing correlations predicted in T_z=0 nuclei. The closest neighbours of "1"0"0Sn with two active particles, "9"8Cd and "1"0"2Sn, are now known with their lowest excited states. The measured reduced transition probabilities for the decay of the isomeric 8"+ and 6"+ states in "9"8Cd and "1"0"2Sn, respectively, allowed to extract an effective quadrupole charge for neutron and proton in this region of nuclei based on the high configurational purity of the states. While the neutron effective charge appeared to be large and in agreement with expectation, the proton effective charge value is very small (e_#pi##<=#1). This controversial result, which would indicate that "1"0"0Sn is a very good closed shell nucleus with respect to quadrupole excitation, is not understood. An experimental reason for this result, related to existence of a core excited isomer, observed in the experiment by means of its half life but not #gamma#-rays, which may have escaped observation, can not be definitely excluded and is left as possible explanation. (orig.)Available from TIB Hannover: RA 3692(98-08) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

The W-matrix: A new method for solving the two-body problem

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Class operators as intertwining maps into the group algebra

With the aim of completing the previous study by A. Orlowski and the author concerning intertwining maps between induced representations and conjugation representation, termed here weighted class operators, we compute the latter explicitely for the conjugation representation arising from the regular representation in the group algebra of a compact group. To that efect a theorem of Wigner-Eckart type for weighted class operators obtained from matrix coefficients of irreducible representations of a compact group is proved. Also the previous construction of weighted class operators is reviewed and extended to the case of locally compact groups rather then just compact ones. (orig.)Available from TIB Hannover: RR 1596(309) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Class operators as intertwining maps into the group algebra

With the aim of completing the previous study by A. Orlowski and the author concerning intertwining maps between induced representations and conjugation representation, termed here weighted class operators, we compute the latter explicitely for the conjugation representation arising from the regular representation in the group algebra of a compact group. To that efect a theorem of Wigner-Eckart type for weighted class operators obtained from matrix coefficients of irreducible representations of a compact group is proved. Also the previous construction of weighted class operators is reviewed and extended to the case of locally compact groups rather then just compact ones. (orig.)Available from TIB Hannover: RR 1596(309) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman