Muon Scattering Experiment: E665

John J. Ryan, Ph.D.

E665 Research

I am still a collaborator on Fermilab Experiment-665, the muon-nucleon deep inelastic scattering experiment. E665 had the advantage of very high incident muon energy, 490GeV, which allowed large values of energy exchange and hence very small values of the Bjorken scaling variable, Xbj. In addition, acceptance down to small muon scattering angles (1milliradian) allowed for an examination of the Shadowing effect over large ranges of the kinematic variables:
100 GeV < v < 500 GeV
0.1 GeV^2/c^2 < Q^2 < 150 GeV^2/c^2
0.001 < Xbj < 0.5

Physics

I analyzed the scaled-energy (z) distributions of the produced hadrons from E665. I presented detailed comparisons of these distributions from a xenon target to those from the deuterium target. It was interesting that no nuclear effects could be seen, even in the region of event kinematics known as the Shadowing region. We published this work in reference [8]. I worked closely with Hugh Montgomery, Don Geesaman, and Wolfgang Wittek in writing this article.

I had continued to analyze data from this experiment, working at M.I.T. with Prof. Louis Osborne. We had two undergraduates working on theses on data from the last data collection period.

Hardware

In graduate school, I was M.I.T.'s liaison with the experiment, and I was expected to make many of the decisions regarding M.I.T.'s responsibilities.

I designed and drafted the support frame for the muon proportional tubes for this experiment. This included elements for precise positioning of the proportional tubes in their frames. I procured the materials and ordered extrusions from a manufacturer of aluminum products. I managed the entire project, from bidding to machining and installation.

I also worked closely with a Fermilab engineer to design the support structure for these proportional tubes. I managed a crew of technicians and two other graduate students to assemble the frames and to install all the proportional tube detectors.

I designed and developed a method for ``deadening'' the high-intensity beam region of the proportional tubes. I machined and strung a test module, and I took measurements with cosmic rays to gauge the effect of the deadening.

I calculated a design for cooling the electronics of these proportional tubes by forcing air through the box-beams of the support frame. I took measurements to determine the power needed to force the air against the pressure head built-up in the box-beams.

I took responsibility for implementing and debugging the read-out electronics for the proportional tubes. I redesigned the interface between the electronics and the tubes to allow tolerance in attaching each channel. I debugged the digital control module which drove the multiplexed shift-out of the signals from the tubes. I traced down and fixed the faults in a number of the CAMAC RAM modules, which were to receive these signals. I also designed a clearing-house module which matched the various signal levels: TTL, ECL, and NIM. I managed a crew of collaborators in assembling and cabling the electronics to the proportional tube detectors.

Software

I designed and coded a software system for generically handling machine independent Input/Output of the experiment's Data Structures. I implemented this in CERN's ZEBRA system. I worked with Clive Halliwell on this software effort. The system had to accept parallel input streams to merge the scanned streamer chamber data with the reconstructed electronic data, as well as filter output to several concurrent output streams. We transparently wrote and read data on such disparate machines as Digital VAXes and IBM-style mainframes, as well as Unix workstations.

I entered the software effort of pattern recognition of the data from our wire chambers. After defining precisely the efficiency of pattern recognition versus that of the chambers themselves, I helped tuned the parameters before the full reconstruction effort commenced.

Continuing E665 Research

I have tried to keep abreast of the analyses of several members of the E665 Collaboration, whose work I find compelling. I am also hoping to look at a few distributions of Final State Hadrons from the nice sample of events from the Hydrogen and Deuterium targets of the 1991 Running Period.

E665 has investigated the relationship between diffractive scattering and the ``Shadowing'' effect. Shadowing is the reduction in the per-nucleon cross section as Xbj is decreased. We have scatterings off several nuclei at Xbj's down to 10^-5. We have published several papers on Shadowing and one on diffractive production of rho's. E665 investigated "Large Rapidity Gap" events. There is in the data a very strong correlation of Shadowing and diffraction. ``Most'' of the reduction in the total cross section at low-Xbj occurs in the diffractive component.

I am hoping to draw on this effort and information and work on the ZEUS Experiment, to gain a better understanding of the whole process.

Last modified: Mon Sep 20, 1999