1. e+ Vertical Beam Size during CESR-c Collisions
E. Tanke, R. Holtzapple
Data taken 8/3/2006

2. e+ Average Vertical Beam Size:
Parasitic measurements made during CESR-c colliding beams.
The vertical distribution is averaged over 100 turns (10,000 turn total).
Fit each PMT profile to a Gaussian distribution to determine the sv(15.6 pixels/mm calibration).
Three separate data sets taken at different PMT voltages.
Typical 100 turn average e+ distribution.
PMT=550V
Goodness of fit=0.97
PMT=600V
Goodness of fit=0.95
PMT=650V
Goodness of fit=0.96

3. Average sv for three different PMT voltages.
e+ vertical beam size decreases along each train!
e+ sv decreases with PMT voltage!
Vertical beam size is ~20% larger than previous measurement on 8/1/06.

4. Mean position of vertical distribution for each train.
e+ vertical position increases along each train.

5. Mean position of vertical distribution increases along the bunch train.
e+ sv decreases with PMT voltage!

6. Single bunch current
Correlation between sv and mean position of the vertical distribution.

7. e+ Single Turn Vertical Beam Size:
Single turn vertical distribution for 500 turns.
Typical single turn distribution.
Noisy signal!
PMT=550V
Goodness of fit=0.51
PMT=650V
Goodness of fit=0.65

8. Large oscillation in vertical beam size.
Goodness of fit typically between GOF>0.95 for average sv.

9. Summary
The e+ sv decreases along each trains. The relative mean position of the distribution increases along each train. This is consistent with previous measurements (8/1/06).
sv decreases with PMT voltage.
The single turn vertical distribution is noisy. The goodness of fit is below an expectable level for a reliable measurement.