arXiv subjects

T. Emura

Publications and source records attributed to T. Emura.

3 recordsLinked to original sources

arXiv2000

Probing the DeltaNN component of 3He

The 3He(gamma,pi^+/- p) reactions were measured simultaneously over a tagged photon energy range of 800<E_gamma<1120 MeV, well above the Delta resonance region. An analysis was performed to kinematically isolate Delta knockout events from conventional Delta photoproduction events, and a statistically significant excess of pi+p events was identified, consistent with Delta++ knockout. Two methods were used to estimate the DeltaNN probability in the 3He ground state, corresponding to the observed knockout cross section. The first gave a lower probability limit of 1.5+/-0.6+/-0.5%; the second yielded an upper limit of about 2.6%.

nucl-ex↗

arXiv1999

Measurement of the trailing edge of cosmic-ray track signals from a round-tube drift chamber

The trailing edge of tube drift-chamber signals for charged particles is expected to provide information concerning the particle passage time. This information may be useful for separating meaningful signals from overlapping garbage at high-rate experiments, such as the future LHC experiments. We carried out a cosmic-ray test using a small tube chamber in order to investigate the feasibility of this idea. We achieved a trailing-edge time resolution of 12 ns in rms by applying simple pulse shaping to eliminate a signal tail. A comparison with a Monte Carlo simulation indicates the importance of well-optimized signal shaping to achieve good resolution. The resolution may be further improved with better shaping.

hep-ex↗

arXiv1998

Subthreshold rho^0 photoproduction on 3He

A large reduction of the rho^0 mass in the nuclear medium is reported, inferred from dipion photoproduction spectra in the 1 GeV region, for the reaction 3He(gamma,pi+ pi-)X with a 10% duty factor tagged-photon beam and the TAGX multi-particle spectrometer. The energy range covered (800 < E(gamma) < 1120 MeV) lies mostly below the free rho^0 production threshold, a region which is believed sensitive to modifications of light vector-meson properties at nuclear-matter densities. The rho^0 masses extracted from the MC fitting of the data, m*(rho^0) = 642 +/- 40, 669 +/- 32, and 682 +/- 56 MeV/c^2 for E(gamma) in the 800-880, 880-960, and 960-1040 MeV regions respectively, are independently corroborated by a measured, assumption-free, kinematical observable. This mass shift, far exceeding current mean-field driven theoretical predictions, may be suggestive of rho^0 decay within the range of the nucleonic field.

nucl-ex↗