Difference between revisions of "CDC q vs n"

Revision as of 20:48, 9 May 2016

Run 11559

MPV of Landau fitted to DCDCHit->q for each straw, low gain straws (from hvb I22) in red

The above plot is the MPV of a Landau fitted to q for each straw vs straw number; straw numbers start with 1 in the innermost ring, beam left, and increase clockwise around the ring and then out to the next ring, etc. The low gain straws (red) are near the bottom of the CDC.

amplitude, straws in ring 1

amplitude, straws in ring 28

q, straws in ring 1

q, straws in ring 28

• The slight upward trend in q vs n (straw number) can also be seen in the plots of amplitude and q for rings 1 and 28.
• The oscillations may be an artefact of the fitted Landau MPV moving with the data count in the histogram. ? What would cause this?
• The troughs in the hit count correspond to troughs in the fitted MPV for q.  ???
• The pedestal and amplitude vs n plots do not show huge oscillations, except in number of hits.
• There is a clear oscillation in the hit count vs straw number, which peaks at the sides of the CDC. This is because the mostly vertical cosmic ray tracks pass through many straws at the sides, but only a few above and below. The oscillations should not be present with beam data (but the data probably includes some cosmics).

To-do:

• Repeat with more data
• Use track info - ignore untracked hits
• Pick cosmics out of beam data?
• Beam data oscillations are more sawtooth than sine, why? Runs 11071-11383(?) have the cdc hole.
• Look at drift times

pedestal vs n (straw number)	amplitude vs n	hit count for each straw vs straw number
pedestal vs n, ring 28	amplitude vs n, ring 28	hit count for each straw in ring 28

Run 10496

Run 10496 30nA beam on diamond Feb 24

drift time fit, max drift time 656ns

Run 10777

Run 10777 100nA beam on diamond Mar 6

Run 11667

Run 11667 112nA beam on diamond April 25 after increasing low-gain preamp LV

drift time fit, max drift time 672ns

Low gain straws were n=3064 to 3070, 3270 to 3277, 3479 to 3277

Environment