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

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

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.

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

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

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

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

Large oscillation in vertical beam size. Goodness of fit typically between 0.4-0.8. GOF>0.95 for average sv.

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.