THIS IS A TWIKI PAGE DEDICATED TO ANALYSIS OF THE BIS CHAMBER INSTALLED AT THE H8 TESTBEAM

BIS in H8 and ATHENA

H8

BIS is a C type chamber and was installed in H8 during the last data taking period (October and November runs). It was placed in front of the Liquid Argon Calorimeter fixed to the calorimeter's table. For information on the experimental setup and a nice photo from the H8 area have a look here.

ATHENA

Thanks to Isabel Trigger, 3 packages specific for BIS were provided for reconstructing BIS data. The packages are:

• MuonGeoModel-00-02-13
• MuonTBData-00-00-60
• MuonTBRecExample-00-00-22

We implemented these packages in Muonboy reconstruction package.

ANALYSIS

Runs

The following set of runs are so far used for the analysis

	Run Number	Beam Type	Beam E(GeV)	Table Eta
1	2102470	Positrons	180	0.2
2	2102516	Positrons	180	0.7
3	2102538	Positrons	180	0.6
4	2102675	Muons	350	0.6
5	2102511	Positrons	180	0.5

Calibration constants

DriftTime: The formula used to calculate the drifttime in ATHENA is the following: dtime = ( mdttdc - mtrigger + offset - t0 + coffset)*scale ,where

• mdttdc = tdc counts from mezzanine card
• mtrigger = trigger time from trigger mezzanine
• offset = 1600 (offset imposed by Calib)
• t0 = t0 time of the tdc spectrum
• coffset = 20 (offset imposed by Calib)
• scale = 0.78 (to convert from counts to nsec)

It was recently found out that these particular offsets in the drifttime formula described above, do not apply well to the BIS case and that is why the drifttimes of the reconstructed hits appeared to be shifted. To compansate this, we artificially shifted the t0 time in order for the drifttimes to start from 0.

RT Relations: No dedicated RT relations exist for the runs analysed. We have used an RT produced by the Garfield simulation program.

T0s: T0s were produced from the most illuminated tube of each layer of BIS.

Mapping file

The initial mapping file used for the BIS was found to be incorrect. You can find the new mapping file here and a Persint view of an event with the old and the new cabling map.

Ongoing Results

Have a look at some results by clicking here.

Open Questions

The questions that still need an answer are:

TDC time spectrum

Why is there a discrepancy in Tmax between the muon run 4 and the positron runs 1,2,3,5? Example plots of raw TDC spectrum from runs 1 and 4 can be found here. There is a discrepancy in the Tmax time between the two runs of about ~130nsec.

Beam width

What is the beam width for the muon run? Is a small beam width hypothesis sufficient to explain the above discrepancy? The beam width can be calculated from the beam chambers which were installed before the Inner Detector in H8. For the positron runs 1,2,3 an exaple of the width is shown here. It is of the order of ~30mm (1 tube).

-- KonstantinosBachas - 26 Nov 2005