A. Passeri

The KLOE electromagnetic calorimeter

Abstract The KLOE calorimeter is a fine lead-scintillating fiber sampling calorimeter. We describe in the following the calibration procedures and the calorimeter performances obtained after 3 years of data taking. We get an energy resolution for electromagnetic showers of 5.4%/ E (GeV) and a time resolution of 56 ps/ E (GeV) . We also present a measurement of efficiency for low-energy photons.

Data handling, reconstruction, and simulation for the KLOE experiment

Abstract The broad physics program of the KLOE experiment is based on the high event rate at the Frascati φxa0factory, and calls for an up-to-date system for data acquisition and processing. In this review of the KLOE offline environment, the architecture of the data-processing system and the programs developed for data reconstruction and Monte Carlo simulation are described, as well as the various procedures used for data handling and transfer between the different components of the system.

Construction and performance of the lead-scintillating fiber calorimeter prototypes for the KLOE detector

The KLOE detector is designed primarily for the study of direct CP violation in K0 decays. The electromagnetic calorimeter, EmC, is a most demanding element of the detector. Two prototypes of the EmC (one for the barrel and one for the end-cap region) have been built at Frascati and tested at PSI (Switzerland) using beams of electrons, muons and pions of 40 to 290 MeV/c momentum, and at the Frascati LADON facility using photons of 20 to 80 MeV. We observe excellent linearity from 20 to 290 MeV. The energy resolution is σ(E)/E ∼ 4.4% / ”E(GeV) and the time resolution is ∼ 34 ps/”E(GeV). We found little dependence on incidence angle and entry position. We also determined that some πμ identification is possible.

Measurements of light yield, attenuation length and time response of long samples of “blue” scintillating fibers

Abstract In connection with the design of the electromagnetic calorimeter of the KLOE detector, we have studied the performance of several samples of commercially available plastic scintillating fibers with a particle beam at the CERN PS. Results on light yield, attenuation length and time resolution measurements concerning 2–4.5 m long samples of those fibers are presented.

The ADCs and TDCs for the KLOE electromagnetic calorimeter

Abstract The KLOE electromagnetic calorimeter processes signals arriving over an interval of ≈200xa0ns before the trigger time. The KLOE ADC is based on two continuously analog baseline subtraction systems. A high stability monostable circuit is used at the input of the TDC operating in common start mode.

Performance of fine mesh photomultiplier tubes in magnetic fields up to 0.3 T

We have studied the performance of fine mesh photomultiplier tubes (R2490-05, R2021, H5756, R3423-01) in magnetic fields up to 0.3 T. The tube gain and the average number of photoelectrons have been measured as a function of the magnetic field, of the angle between the field direction and the phototube axis, and of the rotation of the phototube around its axis. The reduction of the photocathode effective area in a magnetic field has also been measured.

Quality checks and first calibration of the KLOE electromagnetic calorimeter

Abstract The construction of the KLOE lead-scintillating fibres electromagnetic calorimeter has been completed. The final results of the extensive quality checks of all the calorimeter modules are presented here. The measurements have been done in the Frascati Laboratories at a cosmic ray test facility using minimum ionizing particles. The results show that all the calorimeter modules are well fulfilling the design specifications concerning time and energy resolutions. Furthermore, by using the same cosmic ray facility, all the calorimeter elements have been also pre-calibrated.

Study of aging effects in the HPC readout chambers

Abstract The readout chambers of the HPC calorimeter are affected by large aging. This stimulated intense experimental activity aimed at developing a reliable monitor of the evolution of the detector response and at understanding the origin of the aging. Both of these aspects are discussed. Particular attention is devoted to a series of tests performed with HPC units equipped with graphite inserts in the readout chambers.

Construction and tests of a fine granularity lead-scintillating fibers calorimeter

We report the construction and the tests of a small prototype of the lead-scintillating fiber calorimeter of the KLOE experiment, instrumented with multianode photomultipliers to obtain a 16 times finer readout granularity. The prototype is 15 cm wide, 15 radiation lengths deep and is made of 200 layers of fibers 50 cm long. On one side it is read out with an array of 3×5 multianode photomultipliers Hamamatsu type R8900-M16, each segmented with 4×4 anodes, the read out granularity being 240 pixels of 11 × 11 mm2 corresponding to about 64 scintillating fibers each. These are interfaced to the 6 × 6 mm2 pixeled photocathode with truncated pyramid light guides made of Bicron BC-800 plastic to partially transmit the UV light. Each photomultiplier provides also an OR of the 16 last dynodes that is used for trigger. The response of the individual anodes, their relative gain and cross-talk has been measured with the light (440 nm) of a laser illuminating only few fibers on the side opposite to the readout. We finally present the first results of the calorimeter response to cosmic rays in auto-trigger mode.