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BBSIM Beamline Update

As of July 98, the beamline simulation is in the process of being updated. This includes Q4/Q5 simulation done by Sandrine Emery for the HER commissioning; Q2 and endplugs done by Shiral Devmal; inside the support tube done by Chih-hsiang Cheng. The changes have not yet been committed.

As of December 1998, the beamline simulation is ready for use. All major updates have been made (all magnets, fields, and beampipes are available).

General information

  • Status report from S.Devmal on Q2 magnets, vacuum pipes, raft and endplug update.
  • Status pictures from S.Devmal of above items.
  • Status report from C. Cheng on beampipe inside the support tube.
  • Status report from T.L. Geld for the BkgCom meeting on 9/11/98, along with picture of the updated gnbpip package and the downstream and upstream overlap problems between Q2 and the support tube.
  • Here is a link to Terry's presentation on the new gnbpip geometry at the major simulation review of 9/23/98.
  • Here is a link to Terry's presentation on the gnbpip geometry status at the simulation meeting of 10/19/98.
  • Here is a link to Terry's status report on the gnbpip geometry at the simulation parallel meeting of 10/28/98 (presented by Bill Lockman).
  • Here is a link to Terry's discussion on the production of the 100 1nTorr background frames at the production meeting of 12/01/98.
  • Here is a link to Terry's README file on simulating backgrounds, both for background commissioning and for BaBar.

Overlap issues in "TDR" detector

In doing the update, I noticed some overlap problems in the original TDR detector.

  • There are some overlaps between BPMO and SSVD in the BBSIM used in MDCI and MDCII (these pictures used release 6.10.6). The small outcropping in the forward SSVD overlaps the BPMO and overlaps part of the B1 magnet. The third picture also shows the BPMO mother (in red) does not encompass all the magnet volumes.
  • There are also some overlaps between the forward endplug and MCPF .

Overlap issues in the new gnbpip

Both of these problems still exist in the new geometry, but the SSVD one is probably solvable.

  • Overlaps between BPMO and SSVD in the new gnbpip. With the geometry update, most of these should be solvable with changes to both BPMO and SSVD.
  • The overlaps between the forward endplug and MCPF still exist and will require discussion and rework of volumes.
  • 10/19/98: Progress on the IFR/endplug overlap: The major problem causing the overlap between the forward endplug and the MCPF was that both gnbpip and gnmuon were creating the 65mm steel plate which was part of the door. By removing that plate from gnbpip (and incidently fixing an angle miscalculation), the overlap between the endplug and the IFR becomes very small, as shown here . The MCPF mother volume still extends too far in z and overlaps the back end of the endplug. This needs to be fixed, but updated info is necessary.

This page is maintained by Terry Geld (

Last modified: Wed Dec 16 15:36:16 PST 1998