[en] Charm production results from the 1985 data run of E653 are presented and compared with previously published measurements. The total inclusive charm cross section and differential cross section in X_f and P²_t are discussed. Fits to dσ/dX_fdP_t²∼(1-X_f)ⁿ. e^-bP_t² yields a value of n = 11 ± 2.0 and b=1.1±0.2(GeV/c)^-2. Productions results from a sample of 47 charm pair events are presented, including the X_f, P_t², mass and azimuthal opening angle distributions. Correlations within the charm pair sample are discussed (Data)

[en] We have evaluated the feasibility of using the optical diffraction radiation (ODR) generated as a 1- to 6-GeV CW electron beam passes nearby the edge of a single metal conducting plane as a nonintercepting (NI) relative beam size monitor for CEBAF. Previous experiments were successfully done using near-field imaging on the lower-current, 7-GeV beam at APS, and an analytical model was developed for near-field imaging. Calculations from this model indicate sufficient beam size sensitivity in the ODR profiles for beam sizes in the 30- to 50- micron regime as found in the transport lines of CEBAF before the experimental targets. With anticipated beam currents of 100 muA, the ODR signal from the charge integrated over the video field time should be -500 times larger than in the APS case. These signal strengths will allow a series of experiments to be done on beam energy dependencies, impact parameters, polarization effects, and wavelength effects that should further elucidate the working regime of this technique and test the model. Plans for the diagnostics station that will provide reference optical transition radiation (OTR) images will also be described.

[en] Large dynamic range (Peak/Noise > 10⁵) beam profile measurements are routinely performed in the Hall-B beamline at Jefferson Lab. These measurements are made with a 1 to 10 nA electron beam current with energies between 1 to 6 GeV. The electron beam scatters off of a thin W or Fe wire and the scattered particle/shower is detected via scintillation or Cerenkov light several meters downstream of the wire. This report describes results on increasing the dynamic range by using multiple wires of varying diameters. Profile measurements with this large dynamic range are of use for accelerators with large amount of stored energy (e.g. energy recovering linacs) where small beam loss represents a significant amount of beam power. Results on measuring the transverse profile with large dynamic range during the CEBAF energy recovery experiment is also presented. (author)

[en] A lead-liquid argon electromagnetic calorimeter has been constructed for Fermilab experiment E-653. The design, operation, energy and spatial resolution, and analysis are described. A description of a unique read-out geometry which gives the detector powerful pattern recognition capability is also given

[en] The future experimental program at Jefferson Lab requires an absolute current calibration of a 1 μA CW electron beam to better than 1% accuracy. This paper presents the mechanical and electrical design of a Tungsten calorimeter that is being constructed to provide an accurate measurement of the deposited energy. The energy is determined by measuring the change in temperature after beam exposure. Knowledge of the beam energy then yields number of electrons stopped by the calorimeter during the exposure. Simulations show that the energy lost due to electromagnetic and hadronic particle losses are the dominant uncertainty. Details of the precision thermometry and calibration, mechanical design, thermal simulations and simulations will be presented. Escaping particles represent the dominant loss and uncertainty. Thermal and mechanical design limits radiation and conduction losses to the 0.2% level. The design minimizes actual beam time required to take a measurement and allows a measurement to be repeated within 20 mn

[en] The proceedings of Working Group 4 of the 2005 Energy Recovery Linac (ERL) workshop are summarized. Working Group 4 dealt with the challenging topic of beam diagnostics for ERL machines. Energy Recovery Linacs represent a challenge for beam diagnostics from several perspectives; invasive versus non-invasive diagnostics, longitudinal and transverse beam diagnostics, overall machine timing/synchronization and machine protection. Beam diagnostics for an ERL can benefit strongly from the experience at third generation light sources, recirculating linacs and presently operating ERLs. During the workshop there were presentations from all these communities, representing a large range of experience in beam diagnostics. A brief summary Working Group 4 discussion is presented in this paper

[en] The hypernuclear physics program at Jefferson Lab [JLAB] requires a tight upper limit on the RMS beam energy spread of σ_E/E<3x10^-5. The energy spread is determined by measuring the beam width at a dispersive location (D∼4m) in the transport line to the experimental halls. Ignoring the intrinsic beam size, this low energy spread corresponds to an upper bound on the beam width of σ_beam<120μm. Such small beam sizes cannot be measured using direct imaging of the synchrotron light due to diffraction limitations. Using interferometry of the synchrotron light the resolution of the optical system can be made very high. The non-invasive nature of this measurement is also very advantageous as it allows continuous energy spread monitoring. Two synchrotron light interferometers have been built and installed at Jefferson Lab, one each in the Hall-A and Hall-C transport lines. The two devices operate over a beam current range from 10 to 120μA and have a spatial resolution better than 10μm. The structure of the interferometer, the experience gained during its installation, beam measurements and energy spread stability are presented

[en] The fraction f of D⁰ semimuonic decays which occur through the Kμν mode has been measured in a hybrid emulsion spectrometer. Analysis of 124 semimuonic D⁰-decay candidates gives f=0.32±0.05 (stat) ±0.05 (syst). From this measurement and existing data on the D⁰ semileptonic branching ratio and lifetime, we obtain the branching ratio R(D⁰→K^-μ⁺ν)=(2.4±0.4±0.5)% and partial decay rate Γ(D⁰→K^-μ⁺ν)=(5.6±0.9±1.2)x10¹⁰ s^-1

[en] A hybrid apparatus consisting of a movable emulsion target and a magnetic spectrometer was used in a fixed target Fermilab Tevatron experiment to study the production of heavy quarks by high-energy hadron beams. High-resolution silicon microstrip detectors were used for precise tracking in the dense particle environment. Details of the experimental apparatus, including the data acquisition system, are described. (orig.)

[en] We report results on D⁰ and D⁺ production in proton-emulsion interactions at √s = 38.7 GeV. A fit to the form (1-vertical strokex_Fvertical stroke)ⁿ exp(-bp_T²) yields n = 6.9 sub(-1.8)sup(+1.9) and b=0.84 sub(-0.08)sup(+0.10) (GeV/c)^-2. The total inclusive cross section, assuming linear A dependence, is measured to be 38 ± 3 (sta.) ± 13 (sys.) μb for the D⁰ and 38 ± 9 ± 14 μb for the D⁺. A comparison of these results with previous measurements indicates that nuclear effects do not strongly influence charm production. The predictions of QCD are in good agreement with our data. (orig.)