D. Grosnick

Measurement of neutron detection efficiencies in NaI using the Crystal Ball detector

A light-emitting apparatus according to the present invention includes: a board on which a plurality of light source units are provided; a partition member provided on the board and enclosing each of the light source units; and a fixing member arranged in a boundary portion between two or more light source units that are adjacent to each other and fixing the board and the partition member.

Measurement of k-p → ηΛ near threshold

We present measurements of the differential and total cross sections and the {Lambda} polarization for the reaction K{sup -}p{yields}{eta}{Lambda} from threshold to p{sub K}-=770 MeV/c, with much better precision than previous measurements. Our cross-section data show a remarkable similarity to the SU(3) flavor-related {pi}{sup -}p{yields}{eta}n cross-section results. The reaction K{sup -}p{yields}{eta}{Lambda} at threshold is dominated by formation of the intermediate {Lambda}(1670)1/2- state.

Upsilon production in U+U collisions at 193 GeV with the STAR experiment

We present a measurement of the inclusive production of Upsilon mesons in U+U collisions at 193 GeV at mid-rapidity (|y| < 1). Previous studies in central Au+Au collisions at 200 GeV show a suppression of Upsilon(1S+2S+3S) production relative to expectations from the Upsilon yield in p+p collisions scaled by the number of binary nucleon-nucleon collisions (Ncoll), with an indication that the Upsilon(1S) state is also suppressed. The present measurement extends the number of participant nucleons in the collision (Npart) by 20% compared to Au+Au collisions, and allows us to study a system with higher energy density. We observe a suppression in both the Upsilon(1S+2S+3S) and Upsilon(1S) yields in central U+U data, which consolidates and extends the previously observed suppression trend in Au+Au collisions.

Measurement of the branching ratio for eta--->pi**0gammagamma decay

The branching ratio (BR) for the rare decay {eta}{yields}{pi}{sup 0}{gamma}{gamma} was measured with the Crystal Ball multiphoton spectrometer. The result, BR({eta}{yields}{pi}{sup 0}{gamma}{gamma})=(3.5{+-}0.7{sub stat}{+-}0.6{sub syst})x10{sup -4}, is in agreement with calculations of chiral perturbation theory to third order. We have used a sample of 28 million {eta} mesons produced at the BNL Alternating Gradient Synchrotron using the {pi}{sup -}p{yields}{eta}n reaction close to threshold. We detail the intricate extraction of the signal, which has about 1.6 thousand {eta}{yields}{pi}{sup 0}{gamma}{gamma} events, from the overwhelming background of {eta}{yields}3{pi}{sup 0} decays and from the {pi}{sup -}p{yields}{pi}{sup 0}{pi}{sup 0}n reaction.

Measurement of K- p --> eta Lambda near threshold

We present measurements of the differential and total cross sections and the {Lambda} polarization for the reaction K{sup -}p{yields}{eta}{Lambda} from threshold to p{sub K}-=770 MeV/c, with much better precision than previous measurements. Our cross-section data show a remarkable similarity to the SU(3) flavor-related {pi}{sup -}p{yields}{eta}n cross-section results. The reaction K{sup -}p{yields}{eta}{Lambda} at threshold is dominated by formation of the intermediate {Lambda}(1670)1/2- state.