Sammy W. Henderson

Design and tests for CLEO-II silicon vertex detector

We report on the design and prototype studies for a new double-sided silicon vertex detector for the CLEO-II experiment at CESR. To minimize multiple scattering, two new techniques are employed: (1) the detector is supported by low mass, low Z boron carbide foam U-channels; and (2) the preamplifiers are removed entirely from the tracking volume by using a second layer of metallization on the silicon to provide longitudinal readout traces for the transverse sense strips.

Studies of radiation damage to CAMEX64 preamplifiers exposed to γ-rays at the Cornell high energy synchrotron source

Abstract CAMEX64 preamplifiers, developed at the MPI-Munich for use in the readout of silicon strip detectors, have been exposed to well-measured doses of monochromatic γ-rays from the Cornell high energy synchrotron source (CHESS) and measurements of the resulting radiation damage have been made. Silicon strip detectors with their associated CAMEXes will be installed close to the interaction region in the CLEO-II experiment at Cornell University, where they will be exposed to both charged particle and photon fluences. Powered and unpowered CAMEXes were irradiated and after each exposure measurements of pedestals, gains, coherent and incoherent noise were made, until the devices could no longer be read out. Results are quoted for noise and gain degradation as a function of dose.

Studies of double-sided, double metal silicon strip detectors

Abstract We have studied double-sided, double-metal silicon microstrip detectors for the CLEO-II vertex detector. The double-layer structure permits the transverse strips to be connected via longitudinal readout traces to preamplifiers located at the end of the detectors. The detectors are manufactured by Hamamatsu Photonics. They are full size AC coupled detectors with polysilicon bias resistors on the n-side and punchthrough biasing on the p-side. We present measurements of detector static properties, including the extra capacitance due to the double layer structure, as well as measurements of signal and noise.

Two-body Ds+ decays to , , , , and +

We have made measurements of several {ital D}{sub {ital s}} branching ratios, relative to the {phi}{pi}{sup +} mode. We have observed two previously unseen two-body hadronic decays of the {ital D}{sub {ital s}}{sup +}, namely {eta}{rho}{sup +} and {eta}{prime}{rho}{sup +}, and measured relative branching ratios of 2.86{plus minus}0.38{sub {minus}0.38}{sup +0.36} and 3.44{plus minus}0.62{sub {minus}0.46}{sup +0.44}, respectively. We have determined the relative branching ratio for the decay into {phi}{rho}{sup +} to be 1.86{plus minus}0.26{sub {minus}0.40}{sup +0.29}. In addition, we have measured relative branching ratios for the {eta}{pi}{sup +} and {eta}{prime}{pi}{sup +} states, for which there had previously been conflicting measurements; our results are 0.54{plus minus}0.09{plus minus}0.06 and 1.20{plus minus}0.15{plus minus}0.11, respectively. Combining these new measurements with previous results and using (3.7{plus minus}1.2)% for the value of {ital scrB}({ital D}{sub {ital s}}{r arrow}{phi}{pi}{sup +}), we can account for {approx}(79{plus minus}26)% of all {ital D}{sub {ital s}}{sup +} decays. In addition we have also measured relative branching ratios or set upper limits on {ital D}{sup +} decays to all of the above-mentioned final states.