11,716 research outputs found
Jets and Prompt Photons in Photoproduction at ZEUS
In the ZEUS experiment at HERA, photoproduction processes have been studied
for photon-proton centre-of-mass energies in the range 100 < W_gamma p < 300
GeV and jet transverse energies extending to E_T^jet ~ 70 GeV. The data
contribute to our understanding of QCD dynamics, and also provide new
constraints on the photon's parton density.Comment: 7 pages, 12 figures, talk given at ICHEP'98, writeup also available
at http://ppewww.ph.gla.ac.uk/preprints/98/05
Rapidity Gaps in Hard Photoproduction
Recent results obtained from studies of diffractive processes in hard
photoproduction performed by the ZEUS collaboration using data delivered by
HERA in 1993 and 1994 are presented. In particular, we have found that \% of events with two jets at a pseudorapidity interval of 3.5 to 4 are
inconsistent with a non-diffractive production mechanism. These events may be
interpreted as arising due to the exchange of a colour singlet object of
negative squared invariant mass () around 40~GeV. We have also probed
the structure of the exchanged colour singlet object in low-- diffractive
scattering. By comparing the results from photoproduction and electroproduction
processes we find that between 30\% and 80\% of the momentum of the exchanged
colour singlet object which is carried by partons is due to hard gluons.Comment: 13 pages. 13 postscript figures + 1 postscript preprint logo + 1
LaTeX file. Files tarred, gzipped and uuencoded into 1 file. Also available
at http://ppewww.ph.gla.ac.uk/preprints/96/03
Permanent-magnet atom chips for the study of long, thin atom clouds
Atom-chip technology can be used to confine atoms tightly using permanently magnetised videotape along with external magnetic fields. The one-dimensional (1D) gas regime can be realised and studied by trapping the atoms in high-aspect-ratio traps in which the radial motion of the system is confined to zero-point oscillation
Automatic focus control for facsimile cameras
An electronic circuit for controlling the focus of facsimile cameras is described. The circuit consists of balanced a.c. amplifiers, two square law function generators, and a differential amplifier and power drive. The invention includes a method for maintaining the imaging sensor at the expected location of the focal plane as the facsimile camera scans a scene or terrain. A block diagram of the electronic circuitry is provided
Laser communication system for controlling several functions at a location remote to the laser
A multichannel laser remote control system is described. The system is used in areas where radio frequency, acoustic, and hardware control systems are unsatisfactory or prohibited and where line of sight is unobstructed. A modulated continuous wave helium-neon laser is used as the transmitter and a 360 degree light collector serves as the antenna at the receiver
Colour Coherence in Photon Induced Reactions
Colour coherence in hard photoproduction is considered using the Monte Carlo
event generators PYTHIA and HERWIG. Significant effects in the parton shower
are found using multijet observables for direct and resolved photon induced
reactions. The particle flow in the interjet region of direct processes shows a
strong influence of string fragmentation effects.Comment: 6 pages, LaTeX, 6 eps figures included, to appear in the proceedings
of the workshop "Future Physics at HERA
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