Section 1: Upsilon logbook investigation

Dynamic masking from logbooks

The online upsilon trigger kept a record of the dynamic masking per run, this is a list of the dynamic masking over run 07 and 08

List of dynamic masking run 7 and 8

This plot shows the dynamic bad towers masked and the towers that recovered is shown in red

Accepted vs. Seen

The amount of events fed to the Upsilon trigger is recorded in the logbook as "Seen" and the amount the trigger keeps as "Accepted". The ratio of "Seen vs. Accepted" should be constant. For the AuAu runs this ratio was about 2 and for the dAu runs it was about 20

AuAu seen/accepted

dAu seen/accepted

For AuAu this seem stable but for dAu notice the peak near 15. To investigate this I plotted the ratio vs. run number

It seems there is a region of runs, 8346k to 8351k, where the upsilon trigger acceptance changed. The barrel plots during this period show noise in an area of phi=1 and eta 0-1.

Example of good run: Notice the BEMC is uniform

In range 8346k to 8351k note noise at phi=1 eta 0-1 range:

Section 2: Trigger Cluster and Dynamic masking investigation

I have intergrated the trigger code into the analysis. The trigger has some variations that I was interested in looking at to see the effect on the spectra

I ran four trigger simulation cases for picking "tracks" to make pairs per. event with the run 8 dAu data

  1. The trigger simulation code with all the dynamic masking switched off

  2. The trigger simulation code with the dynamic masking switched on

  3. The trigger simulation code with all the towers masked dynamically found from the trigger logbook record

  4. The "cluster case" where the track traced to one of the trigger id clusters and no the seed tower

The first case has no dynamic masking in the simulator. Apart from these test, it will also be useful in the future to run this on the embedded data and compare to the dynamic masking

The second case simulates the trigger as it was during the online data taking. Here a test will be made to see if the difference in masking found by running over uDsts vs. the real online masking will have any effect

The forth case was to try to emulate the trigger as close as possible to "online dynamic masking". Here the online dynamic masked towers were recreated from the logbook and applied "per run". This is not exact as the event number recorded by the trigger will not match the event number recorded in the uDst, so we can only gather all the towers masked in a run and apply them togther instead of switching them on (or off) exaclty as they were during the run. This assumption is however a harsher cut than the dynamic masked towers used during a real data taking and is good to get a rough estimate of the effect

The final case is related to matching a TPC track to towers. We can track to the center of a "Seed" tower or the 3x3 array around the seed tower.

Offline masking vs. no masking

No dynamic masking

Offline dynamic masking


Masked towers were very rare when separate uDst, which are segments of a full run, were analysed individually. The Upsilon trigger will reset for each new file and the masks are rare. If the uDst files were grouped into runs and analysed together more towers would be masked but this will have no relation to the real online conditions and is best avoided. The integral between 8GeV to 11GeV is 186 counts

Online masking vs. no masking

No dynamic masking

Online dynamic masking


In this case we have applied the online dynamic masking from the upsilon trigger logbook "per run", i.e we applied all masks found in a logbook for that run and compare that to the case with the dynamic masking switched off in the Upsilon trigger. Tracks were then matched with the pairs found by the trigger. The effect is small. For the range 8GeV to 11GeV the integral is 186 counts with no mask and 184 with the online mask, about a 1% change. This method of applying all masks found for a run is a harsher selection than the real dynamic masking would be and we can conclude that the effect of dynamic masking is very small at less than 1%

Online masking with track to seed vs. track to seed plus array

The trigger returns the seed and and array of towers around the seed, during tracking we can match to either the seed tower or the seed plus array to compensate for errors on the edge of a BEMC tower. However, Murad had another method to overcome this, by extrapolating the track to the centre of a tower, near the SMD, which is the method I use in all my analysis

Track traced to centre of tower and matching L2 seed tower

Track traced to centre of tower and matching L2 array around seed


In this case adding the array gave a few more counts, for the integral between 8GeV to 11GeV for the seed tower gave 184 counts and the seed plus cluster gave 188 countsas the tracking will match more towers, about 2% more. In this case the spectra look similar but it will be interesting to see how this case acts with the AuAu data with denser tracks


Upsilon log book

Upsilon simulator on the uDst