Tracking Group

  Primary Collimator Live Page

  Tony's Status Report

  Klaus's Status Report
  Michael's Status Report
  Yongguang's Status Report
  Jim's Status Report



  Tony's Plots 1
  Tony's Plots 2



  Qweak Simulation Forum

  Keep Out Zones a la Allena

  Previous Reports

           Collimator working group

A primary collimator technical report is in the works.

Figure 1 - A picture of the collimator region with dimensions.

The above picture is a scaled drawing of the collimator region, with dimensions. In parentheses I have included the center of each element in z along with the total length in z. The vertical lines are the "detectors" used in the simulation and the centers are given (each is .5cm thick). They are placed so they are edge to edge with the element they are next to, but do not overlap. The dimensions at the bottom are given for the distance between the edges of the various elements.

           Beamline Design

Preliminary beamline design to accomodate the desired angular range for the luminosity monitors is underway. The desire is that all "first bounce" stuff would interact as far upstream as possible, and whatever was needed for the lumi's would not interact in the beamline after this point. The desired angular range for the luminosity monitors is up to .8 degrees.

The limiting aperature here is the beampipe through QTOR. We plan to predict photon rates caused by showers in the beamline and shielding for Regions I and II and the cerenkov bar location for the following three scenarios:

           a single tungsten plug at the upstream cleanup collimator location (limits angular range of lumis)
           a tungsten plug at both cleanup collimator locations (larger lumi angular range, two "hot" spots)
           no tungsten plugs and stop everything with the beamline and shielding

To finalize the design, we need to know the maximum beampipe size through QTOR. We'd also like to know "standard" beampipe sizes so that the whole beamline won't have to be custom made.

           Drift Chamber Update

Dave Mack and Roger had some useful suggestions/comments after seeing the VT drift chamber presentation at the collaboration meeting. Our test data from the prototype did not seem to match the GARFIELD simulations. Although we always generated the proper angular range, the tracks started at the edges of the cell of interest. When we start tracks in adjacent cells, the simulation data more closely resemble the prototype test data.

Figure 2a - Experimental drift time histogram for prototype chamber.	Figure 2b - GARFIELD drift time histogram for similar chamber, with tracks starting in adjacent cells.