Hardware Experience
John J. Ryan, Ph.D.
Machining:
I apprenticed in the Machine Shop at Princeton
University, after my junior year.
I learned how to use a Milling machine, a Lathe, an Aecetyline torch,
an Arc Welder, a spot welder, and various other pieces of equipment.
I also had to make extensive use of a broom and a vacuum, to clean up
after myself.
I designed and constructed a reflection/transmission
assembly for a laser, for a lab course project.
Cryogenic Experiment:
For my Senior Thesis at Princeton University, I performed a
Coulomb's Law experiment at liquid helium temperatures. For this
experiment, my machining experience was a great asset.
I designed and constructed a system for coating the
inside surface of pyrex tubing with copper.
I mixed an Epoxy substrate with silica crystal to
match the coefficient of expansion of the pyrex tubes and then machined
the interconnections out of these castings.
I developed a device which was used in an
evacuated bell jar, to sputter copper from a wire onto the inside
of the tube, forming the conductive surface.
I machined a set of clamps with Teflon bushings which allowed the tube
to spin; it was driven by a small eletric motor, and an O-ring was used
as a drive belt.
Mechanical Design:
In graduate school,
I was M.I.T.'s liaison with the Fermilab Muon Scattering
Experiment, E665, 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,
ordering 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.
Detector R&D:
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.
Electronics:
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.
Experiment Design:
As a Research Scientist at M.I.T., I worked on the PHOBOS experiment
for RHIC.
I worked with Wit Busza from M.I.T. and Steve
Manly from
Yale to layout the initial design of the PHOBOS detector. We listed
our physics goals on one hand and our financial constraints on the
other. Working down to the minimum detector specifications and the
maximum number of elements and electronic channels, we found the problem
to be fairly tightly constrained, and we came away with a design which
held up fairly well to subsequent Monte Carlo GEANT simulations.
Silicon Detectors:
I spent the majority of my time on PHOBOS working with the silicon
detectors; I was the Manager of the Silicon
Detectors for the experiment. 85% of the experiment's detectors are
being constructed from silicon. I was responsible for the design of the
devices, and I did a lot of prototype work in choosing the design.
This work included testing the technically challenging aspects of
the devices by building prototypes and by developing testing procedures.
The PHOBOS project needed pad (pixel) detectors with low
mass but high rate capability. I worked closely with Dr. Hobie
Kraner at Brookhaven National Laboratory's Instrumentation Division in
this research and development work.
We experimented with several types of insulating material
applied over a silicon pad device, over the top of which we etched metal
traces to carry the signals from the pads to the edges of the device.
With such thin layers of dielectric, we had to investigate the
capacitive coupling of the traces to the other pads over which they ran.
We performed detailed measurements of capacitance and cross talk.
I designed a prototype device to measure the parameters
necessary to operate an AC-coupled silicon device, biased by a FOXFET
structure.
I did the layout work in AutoCAD.
Hobie Kraner produced this device at BNL, and I tested it at
MIT.
The National Central University in Taiwan produced a silicon pad
detector for use in the CERN experiment WA98. As MIT was involved in
this experiment, we tested this device at MIT. This device was
AC-coupled, biased with polysilicon resistors. We performed initial
tests on an Aelisi probe station and more extensive tests with the
devices bonded to hybrid electronics.
LabVIEW and VME:
In the measurements of the silicon devices,
I employed the LabVIEW system to automate the procedures as much as
possible. I had to develop some Virtual Instrument drivers for
some of our pieces of equipment: the SRS silicon bias power supply, the
Keithley picoammeter/source, and the Boonton capacitance meter. Then,
Guenther Roland and I developed some Virtual Instrument test
procedures. We also employed the LabVIEW Code Interface Node system of
linking in C-programs to speed up the I/O across the GPIB bus.
I also constructed a VME based setup for multiplexing many
channels through the test procedure. I controlled this setup through
LabVIEW, as well.
Last modified: Mon Sep 20, 1999