J. Kuehler

EVIDENCE FOR PARTON KT EFFECTS IN HIGH-PT PARTICLE PRODUCTION

Inclusive pizero and direct-photon cross sections in the kinematic range 3.5 < pT < 12 GeV/c with central rapidities are presented for 530 and 800 GeV/c proton beams and a 515 GeV/c pi- beam incident on beryllium targets. Current Next-to-Leading-Order perturbative QCD calculations fail to adequately describe the data for conventional choices of scales. Kinematic distributions from these hard scattering events provide evidence that the interacting partons carry significant initial-state parton transverse momentum (kT). Incorporating these kT effects phenomenologically greatly improves the agreement between calculations and the measured cross sections.

Measurement of direct-photon production at the Fermilab Tevatron fixed target energies

Measurements of the production of high transverse momentum direct photons by a 515 GeV/c {pi}{sup -} beam and 530 and 800 GeV/c proton beams in interactions with beryllium and hydrogen targets are presented. The data span the kinematic ranges of 3.5<p{sub T}<12 GeV/c in transverse momentum and 1.5 units in rapidity. The inclusive direct-photon cross sections are compared with next-to-leading-order perturbative QCD calculations and expectations based on a phenomenological parton-k{sub T} model.

Calibration and performance of the E706 lead and liquid-argon electromagnetic calorimeter

Abstract We report on the calibration and performance of a large lead liquid-argon electromagnetic calorimeter used by experiment E706 at Fermilab. The reconstructed π 0 mass was used to calibrate the energy response of the calorimeter. The systematic uncertainty in the linearity and uniformity of the mean-energy response of the calorimeter after calibration was found to be less than ±0.5% for the sample of data analyzed. Detector characteristics, including sampling fluctuations and position resolution, are discussed.

Production of charm mesons at high transverse momentum in 515-GeV/c pi- nucleon collisions

We present results on the production of high transverse momentum charm mesons in collisions of 515 GeV/c negative pions with beryllium and copper targets. The experiment recorded a large sample of events containing high transverse momentum showers detected in an electromagnetic calorimeter. From these data, a sample of charm mesons has been reconstructed via their decay into the fully charged K pi pi mode. A measurement of the single inclusive transverse momentum distribution of charged D mesons from 1 to 8 GeV/c is presented. An extrapolation of the measured differential cross section yields an integrated charged D cross section of 11.4+-2.7(stat)+-3.3(syst) microbarns per nucleon for charged D mesons with Feynman x greater than zero. The data are compared with expectations based upon next-to-leading order perturbative QCD, as well as with results from PYTHIA. We also compare our integrated charged D cross section with measurements from other experiments.

Evidence for parton

Inclusive pizero and direct-photon cross sections in the kinematic range 3.5 < pT < 12 GeV/c with central rapidities are presented for 530 and 800 GeV/c proton beams and a 515 GeV/c pi- beam incident on beryllium targets. Current Next-to-Leading-Order perturbative QCD calculations fail to adequately describe the data for conventional choices of scales. Kinematic distributions from these hard scattering events provide evidence that the interacting partons carry significant initial-state parton transverse momentum (kT). Incorporating these kT effects phenomenologically greatly improves the agreement between calculations and the measured cross sections.

k_{T}

Abstract Measurements of the signal to noise, charge sharing, cluster distribution properties, charge correlation and spatial resolution as a function of angle of incidence have been conducted in a high energy pion beam at Fermilab for a variety of DC-coupled double-sided silicon microstripe detectors (Micron, Inc.) utilizing a special boron-spray technique for ohmic side isolation. Readout was accomplished with the Berkeley SVX-D IC/SRS/SDA sequencer system. Stripe pitch configurations included 50 μm and 25 μm with every stripe read out (“50 ∗ 1”, “25 ∗ 1”), and also with every other stripe read out (“50 ∗ 2”, “25 ∗ 2”). One of the detectors under study was 158 μm thick, rather than the usual 300 μm. Of interest are the establishment, for 300 μm thick detectors, of sub-2.5 μm resolution perpendicular to the beam on an ohmic side with 38 mm long stripes for both 25 ∗ 1 and 25 ∗ 2 configurations, and diode side (58 mm stripes) resolutions ranging from below 3 μm at near normal incidence to about 11 μm at 60°. At large angle the 25 ∗ 2 configuration generally gave comparable or better resolution than 25 ∗ 1. The thin detector gave a resolution ranging from about 5.5 μm at 21° to about 7 μm at 45° for 25 ∗ 1 and 6.4 to 9.0 μm for 25 ∗ 2, which, for each of the three common angles of data, was better than the resolution yielded by the 300 μm detector to which it was compared. Signals and charge sharing results are compared to detailed Monte Carlo calculations based on an energy loss distribution due to Bichsel.

effects in high

We present results on the production of direct photons, {pi}{sup 0}, and {eta} mesons on nuclear targets at large transverse momenta (p{sub T}). The data are from 530 and 800 GeV/c proton beams and 515 GeV/c {pi}{sup -} beams incident upon copper and beryllium targets that span the kinematic range of 1.0<p{sub T} < or approx. 10 GeV/c at central rapidities.

p_{T}

We present results on the production of high transverse momentum pizero and eta mesons in pi-p and pi-Be interactions at 515 GeV/c. The data span the kinematic ranges 1 < p_T < 11 GeV/c in transverse momentum and -0.75 < y < 0.75 in rapidity. The inclusive pizero cross sections are compared with next-to-leading order QCD calculations and to expectations based on a phenomenological parton-k_T model.

particle production

The tracking performance of a 0.64 cm square double-sided AC-coupled detector manufactured by Hamamatsu Photonics Inc. has been evaluated in a test beam of 227 GeV/c pions at Fermilab. The detector was fabricated with 50 μm pitch on the ohmic (n) side and 25 μm pitch on the diode (p) side. Readout pitch for both sides was 50 μm and was implemented with a Berkeley designed SVX-D IC/SRS/SDA sequencer system. Measurements were made of signal-to-noise, charge correlation characteristics and resolution vs. angle of incidence in the range from 0° to 60° with analog pulse height information. Measurements were made at room temperature, −12°C and −20°C.

Charge sharing and resolution studies of double-sided silicon microstripe detectors with boron spray implants

Single- and double-sided AC-coupled detectors and double-sided DC-coupled detectors read out with the Berkeley SVXD chip are being studied. The authors report on the signal and noise characteristics for typical single channels and the channel-to-channel variations in noise, gain, and pedestal values. Because collider detectors encounter tracks at all angles of incidence, the authors studied the response of the prototypes over a wide range of angles to see whether the cluster size and charge sharing properties of the various detectors are different. For angles at approximately 0 degrees , the resolution of the double-sided detector is 4.5 mu m on the ohmic side and 3.5 mu m for the single-sided AC coupled detector. The signal-to-noise ratio for the double-sided detector is 25:1, while for the single-sided detector it is 38:1.<<ETX>>