CFT Occupancy dependence on Beam Luminosity

David Lam

Oct 2003

CFT Occupancy vs. Luminosity

Choose 3 classes of events for the study: Zero-biased triggered Minimum-biased triggered Jet triggered – JT_45TT specifically

Events with delivered luminosity range from 6E30 to ~40E30 (cm-2 s-1)

Two set of events: Set 1: 10 events between Feb and Mar 2003 Set 2: 11 events in August (just before the shutdown)

Method

Use a modified version of cft_offline_mon Use D0TriggerFilter to pick out the desired

events Since most of the reconstructed events are still

generated using p13, we used raw data instead to get rid of the 20 ADC cut

Plot average occupancy vs. the middle point of the delivered luminosity range.

Occupancy distribution

Results

Fitting results show occupancies increased with luminosity as expected Top line: Jet triggered Middle line: Min-biased triggered Bottom line: Zero-biased triggered

MC min-biased and zero-biased events are also included.

When extrapolated, at 200E30, jet triggered occupancy is approximately: 0.233 (CFTX 1)

Events between Feb. and Mar.

Events in Aug (before shutdown)

Result

Zero-biased events triggered on beam crossing: Contain mostly electronic background “noise” Occupancy variation due to p/anti-p halo

Min-based events triggered on collision: Signal in luminosity monitors above threshold on both ends Number of collision increases with luminosity – Poisson

distribution Supposedly, occupancies increase faster with luminosity

compared to zero-biased event. But, slopes for the fits of min-biased events are lower

than zero-biased and jet triggered – so dig deeper….

Trigger luminosity

Look into the recorded luminosity for each event

Recorded luminosity are stored by luminosity block (lbn), which usually corresponds to time interval of 1 minute.

Plot occupancy vs. record luminosity for each trigger

Zero-biased Events (Set 1)

Zero-biased Events (Set 2)

Result (cont.)

Both set of zero-biased events have positive dependencies on luminosity

However, for set 1 min-biased events, some funny looking structure in the plot

Set 2 min-biased events have occupancies DECREASE with increasing luminosity

Min-biased Events (Set 1)

Min-biased Events (Set 2)

Jet triggered Events (Set 1)

Jet triggered Events (Set 2)

Jet-triggered events recorded luminosity distribution

Set 1

Set 2

Jet triggered result

Set 1 jet triggered occupancies increase with increasing luminosity in range 0 – 900 ub-1

But set 2 occupancies DECREASE with increasing luminosity in range 0 – 150 ub-1

Why the range of recorded luminosity differed? Given that the delivered luminosity range are the same in both sets.

Comments? Suggestions?