Last updated: 19 October 2004 by Michael Kelsey
The BaBar Prototype II Drift Chamber (Proto II) was built by
SLAC's Experimental Group C in 1996, to implement and validate the cell
design and gas mixture for the real BaBar Drift Chamber. It is installed in
the main laboratory of SLAC's Experimental Group C, in Central Lab Annex
B273. Proto II uses production BaBar electronics and data acquisition
components, and a three-counter scintillator telescope (with range stack)
Hazards and Safety Procedures
History and Operation
("Prototype I" was an electronic mock-up to validate the electronics
design, by providing a base on which to mount the front-end assemblies,
supply artificial pulses to the readout systems and monitor their output.)
Proto II was last operated in late 1998 and early 1999, during the final
commissioning of the full BaBar Drift Chamber. Once PEP-II began delivering
colliding beams (May 1999), operation and support of Proto II was suspended,
as manpower and resources were redirected to detector operations and physics
Since July 2001, a small group is working to restore Proto II to operation using
the current BaBar detector control and data acquisition systems. This will
provide a functional test stand for a variety of purposes, which up to now
have required the full detector, including
In Jan 2002, Broken wires were discovered in Proto II. This document describes how the broken wires were discovered.
- Validating changes to the drift chamber DAQ software;
- Testing repairs to front end electronics modules;
- Testing different gas mixtures for aging and stability.
In June 2002 we mapped the Sense and Guard wires on Proto II to discover how many and which were broken.
We have completed the first pass of sense and guard wire testing. Examine the results of:
In Short - There are no broken Sense wires and only one Sense wire shows any contact with ground. There are no broken Guard wires though two show contact with ground.
Thanks to Swagato Banerjee and Jignesh Parikh for making these measurements.
New drawings are available that show the position of the broken wire and the Sense and Guard wires contacting
A large number of the engineering drawings and schematics for Proto II are available in
PostScript format in the
Block diagrams showing
the layout and interconnections of the whole Prototype II system were
produced by Lisa Manning during her July-August 2001 project to revive Proto
Photographs of the detector
setup and electronics racks were produced by Karl Bouldin in August 2001.
The geometry of the chamber wires is defined in an ASCII file containing wire locations, stereo angles, twist angles.
Lisa Manning prepared a report
and presentation on her restoration
work during July and August 2001 for the SLAC Summer Science Program. This
report will be expanded into TNDC Note 01-100.
Old performance reviews and presenations
Results from 1997
For comments, questions or changes to this page contact Michael Kelsey
Information Expires: 31 December 2001