Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays

Average charged multiplicities have been measured separately in $b$, $c$ and light quark ($u,d,s$) events from $Z^0$ decays measured in the SLD experiment. Impact parameters of charged tracks were used to select enriched samples of $b$ and light quark events, and reconstructed charmed mesons were used to select $c$ quark events. We measured the charged multiplicities: $\bar{n}_{uds} = 20.21 \pm 0.10 (\rm{stat.})\pm 0.22(\rm{syst.})$, $\bar{n}_{c} = 21.28 \pm 0.46(\rm{stat.}) ^{+0.41}_{-0.36}(\rm{syst.})$ $\bar{n}_{b} = 23.14 \pm 0.10(\rm{stat.}) ^{+0.38}_{-0.37}(\rm{syst.})$, from which we derived the differences between the total average charged multiplicities of $c$ or $b$ quark events and light quark events: $\Delta \bar{n}_c = 1.07 \pm 0.47(\rm{stat.})^{+0.36}_{-0.30}(\rm{syst.})$ and $\Delta \bar{n}_b = 2.93 \pm 0.14(\rm{stat.})^{+0.30}_{-0.29}(\rm{syst.})$. We compared these measurements with those at lower center-of-mass energies and with perturbative QCD predictions. These combined results are in agreement with the QCD expectations and disfavor the hypothesis of flavor-independent fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters

RADIOACTIVE WASTE ECONOMICS: OPTIMUM STORAGE TIME PRIOR TO SHIPPING TO DISPOSAL SITE

The economics of waste disposal by pit storage when the geological location of the pits does not coincide with the location of the processing plant are considered. Optimum cooling times before shipment were determined for 250gallon batches of Purex-type waste. Three distances between processing and disposal sites, and three unit storage costs were considered. It was concluded that as the storage cost increases it becomes economical to ship shorter-cooled waste, and as the shipping distance increases, it becomes economical to store waste longer. In the case of 30/gal/yr storage, for 200 miles shipment, essentially no storage should be provided beyond that required for surge in filling carriers. For less highly irradiated material, the optima would shift in the direction of shorter cooling times. Data are tabulated and presented graphically. (C.H.

PROJECT HOPE: A CHEMICAL REPROCESSING PLANT FOR A NUCLEAR POWER ECONOMY.

The results of the Hope Project, a completely rationalized reprocessing plant, are summarized. An MTR type fuel element was adopted, with U/sup 233/ replacing the U/sup 235/ and a fuel processing rate of 5.5 kg equivalent of U/sup 233/ per day. The chemical process chosen was solvent extraction, using TBP in Amsco. The Hope plant features continuous dissolving; relaxed, yet safe, criticality criteria; sampling only for process control; a realistic approach to waste storage; and a new operating-maintenance philosophy. It was felt that with the process outlined enriched fuel elements could be reprocessed for about one dollar per gram. (L.M.T.

Factorial and cumulant moments in e+ e- ---> hadrons at the Z0 resonance

We present the first experimental study of the ratio of cumulant to factorial moments of the charged-particle multiplicity distribution in high-energy particle interactions, using hadronic Z$^0$ decays collected by the SLD experiment at SLAC. We find that this ratio, as a function of the moment-rank $q$, decreases sharply to a negative minimum at $q=5$, which is followed by quasi-oscillations. These features are insensitive to experimental systematic effects and are in qualitative agreement with expectations from next-to-next-to-leading-order perturbative QCD.Comment: 13 pages, latex file, uuencoded eps figure