High-energy photon beam production with laser-Compton backscattering

We have produced a beam of high-energy gamma-rays by Compton backscattering of $\text{1064}\text{nm}$ laser photons from 1 GeV electrons circulating in a storage ring. Measuring the energy spectra of the backscattering photons with an HPGe detector, we have found that the maximum energy of $\text{17.6}\text{MeV}$ and the measured energy spectra show agreement with the simulation calculations, while the detected photon yields were measured at about 4×10³, 2×10³ and $\text{3×10}{}^2\text{photons}\text{s}{}^{\mathrm{-1}}\text{mA}{}^{\mathrm{-1}}\text{W}{}^{\mathrm{-1}}$ for the 20, 10 and $\text{2}\text{mm}\text{φ}$ collimators, respectively. The photon energy widths from the collimators correspond to 6.6–$\text{17.6}\text{MeV}$, 12.4–$\text{17.6}\text{MeV}$ and 17.3–$\text{17.6}\text{MeV}$, respectively. By using these photons, we measured the total nuclear photoabsorption cross-sections in the E1 giant resonance energy region for ${}^{197}\text{Au}$ using the attenuation method and we have demonstrated that the photon attenuation method will be a useful tool for studying photonuclear reactions.     

Improved surface treatment of the superconducting TESLA cavities

The proposed linear electron–positron collider TESLA is based on $\text{1.3}\text{GHz}$ superconducting niobium cavities for particle acceleration. For a centre-of-mass energy of $\text{500}\text{GeV}$, an accelerating field of $\text{23.4}\text{MV/m}$ is required which is reliably achieved with a niobium surface preparation by chemical etching. An upgrade of the collider to $\text{800}\text{GeV}$ requires an improved cavity preparation technique. In this paper, results are presented on single-cell cavities which demonstrate that fields of up to $\text{40}\text{MV/m}$ are accessible by electrolytic polishing of the inner surface of the cavity.     

Calibration of a neutron time-of-flight multidetector system for an intensity interferometry experiment

We present the details of an experiment on light particle interferometry. In particular, we focus on a time-of-flight technique which uses a cyclotron RF signal as a start and a liquid scintillator time signal as a stop, to measure neutron energy in the range of E_n≈1.8–$\text{150}\text{MeV}$. This dynamic range (up to $\text{300}\text{ns}$) is much larger than the beam bunch separation $\text{(54}\text{ns}\text{)}$ of the AGOR cyclotron (KVI). However, the problem of a short burst period is overcome by using the time information obtained from a fast projectile fragment phoswich detector. The complete analysis procedure to extract the final neutron kinetic energy spectra, is discussed.     

π/p separation at 1.2GeV/c by an emulsion cloud chamber

We have performed an experimental study of π/p separation at a momentum of $\text{1.2}\text{GeV}\text{/}\text{c}$ using an Emulsion Cloud Chamber (ECC) detector with secondary beam produced by the proton synchrotron at KEK. The separation is greater than 3 standard deviations using dE/dx measurements of $\text{2.6}\text{mm}$ long tracks with an automatic emulsion read-out system.     

Data acquisition and monitoring for the KLOE detector

The Data Acquisition system for the KLOE experiment, presently running at the Laboratori Nazionali di Frascati DAΦNE collider, has been designed to sustain an acquisition throughput of $\text{50}\text{Mbyte}\text{/}\text{s}$ for an event rate of $\text{10}\text{kHz}$. Its two major components are the front end data readout, based on custom buses, and a complex network of computers and storage devices hosting a set of distributed processes. The end result is a seamless data transport from the readout system to the storage library, accompanied by concurrent on line calibrations and data quality control.     

TANGO Array.: 1. The instrument

TANGO Array is an air shower experiment which has been constructed in Buenos Aires, Argentina. It was commissioned during the year 2000 becoming fully operational in September, 2000. The array consists of four water Cherenkov detectors enclosing a geometrical area of $\text{∼30,000}\text{m}{}^2$ and its design has been optimized for the observation of Extended Air Showers produced by cosmic rays near the “knee” energy region $\text{∼4×10}{}^{15}\text{eV}$. Three of the detectors have been constructed using 12,000-l stainless-steel tanks, and the fourth has been mounted in a smaller, 400-l plastic container. The detectors are connected by cables to the data acquisition room, where a very simple system, which takes advantage of the features of a four-channel digital oscilloscope, was set for data collection. This data collection setup allows a fully automatic experiment control which does not require operator intervention. It includes monitoring, data logging, and daily calibration of all detectors. This paper describes the detectors and their associated electronics, and details are given on the data acquisition system, the triggering and calibration procedures, and the operation of the array. Examples of air shower traces, recorded by the array, are presented.