Log entry time 06:31:52 on February 05, 2009

Entry number 259035

This entry is a followup to: 258991

Summary

Several Bigbite sieved run have performed with 5.9GeV Beam at near production condition. The result is very encouraging: We can clearly see the sieve for full momentum range!

The initial purpose for this run is confirming angular reconstruction on full production momentum range. Before this test, the angular reconstruction could only been calibrated on 2 momentum points.

A new analytical bigbtie optics model is used to reconstruct the online sieve pattern. I developped this model to perform bigbite 3D momentum reconstruction for Pi0 experiment. Unlike any HRS or Gen Bigbite model, it only requires physical measurables (geometry and magnet strennth) to perform 1st order calculatioion.

This is only very preliminary analysis. Xin will carry out more detailed analysis later.

Preliminary Analysis

The carbon run (5877+5878) are replayed to show preliminary sieve partten.

The new analytical bigbtie optics model reconstructs vertext and momentum consistantly with Gen model. In addition, its out-plane angular reconstruction makes much more sense. Therefore, without special notes, analysis results shown below is calculated by the analytical model:

1. Without any cut, the bigbtie reads a high backgroud. The carbon vertex peak is only 10% of backgroud.
2. Fig1 is vertex with cut on electron (preshower & beta) and negative particle.
3. Fig2 is reconstructed momenum. The cut is the same as step 4. As shown, the momentum range from 500MeV to 2GeV
4. Fig3 shows sieve pattern with cut on electron, negative particle and the 3rd carbon foil from upstream. The plot is tangent of outplan angle VS in-plane angle, in "BB target CS".
   (central foil is the 4th one. it's knon in no field run that bigbite detector package is actually aligned to the 3rd foil)
5. Fig4 shows sieve pattern with same cut as step 4, but it's reconstructed by Gen optics model. The sieve pattern is also clear. However, the outplane angle is off : 1. the sieve is not centered; 2. the scale is zipped to ~60%.
   (In this case, the Gen model is still using the old Gen optics matrix. With an additional correction matrix, it also could reconstruct out plane angle correctly.)

Good Run List 

A series of runs with different configuration (current, target, raster) are performed:

Run #	Configuration	I /uA	Target	Time	Event	Dead Time	Raster
Run 5877	BB dedicated	2	Carbon Foils	5min	300K	21% DT	3x4 Raster
Run 5878	BB dedicated	1	Carbon Foils	10min	902K	31% DT	3x4 Raster
Run 5881	RICH shared	1	Carbon Foils	1hour	1M	36%DT	3x4 Raster
Run 5883	BB dedicated	1	Carbon Foils	5min	500K	28% DT	No  Raster
Run 5884	RICH shared	1	Carbon Foils	1hour	1M	37%DT	No  Raster
Run 5886	RICH shared	1	He3 Cell	1hour	1M	30%DT	3x4 Raster
Run 5887	BB dedicated	2	He3 Cell	7min	339K	17% DT	3x4 Raster
Run 5888	RICH shared	1	He3 Cell	1hour	1M	30%DT	3x4 Raster
Run 5889	RICH shared	1	He3 Cell	1hour	1M	30%DT	3x4 Raster

Time Line

Init: part of DAQ is broken during last access. DL.evtypebits is missing. Time shift in LHRS.

12:50 Control Access Lower bigbite sieve; DAQ problem fixed by Brad (Halog 258985)

01:36 1st dedicated BB Sieved run;

      Run 5877; 2uA; Carbon Foils; 5min; 300K; 21%DT; 3x4 Raster

      ps1=31000,ps2=2,ps3=4100,ps4=16777215,ps5=10000,ps6=4,ps7=65535,ps8=100< o:p>

01:42 2nd dedicated BB Sieved run;

      Run 5878; 1uA; Carbon Foils; 10min; 902K; 31%DT; 3x4 Raster

      ps1=31000,ps2=1,ps3=4100,ps4=16777215,ps5=10000,ps6=1,ps7=65535,ps8=100< o:p>

01:54 Short Test run for RICH: 5879; 5880

01:58 BB Sieved run with RICH; BB trigger is ~100Hz before dead time

      Run 5881; 1uA; Carbon Foils; 1hour; 1M; 36%DT; 3x4 Raster

      ps1=31000,ps2=10,ps3=5,ps4=16777215,ps5=10000,ps6=40,ps7=65535,ps8=100

01:54 Short Test junk run: 5882

03:03 3rd dedicated BB Sieved run;

      Run 5883; BB dedicated;1uA; Carbon Foils; 6min;  500K;   28%DT; No  Raster

      ps1=31000,ps2=1,ps3=50000,ps4=16777215,ps5=100000,ps6=1,ps7=65535 ,ps8=100

03:12 BB Sieved run with RICH; BB trigger is ~100Hz before dead time

      Run 5884; RICH shared; 1uA; Carbon Foils; 1hour; 1M;   37%DT; No  Raster

      ps1=31000,ps2=10,ps3=6,ps4=16777215,ps5=1,ps6=20,ps7=65535,ps8=100< /o:p>

04:17 Change to He3 target. Spot check run 5885

04:23 BB Sieved run with RICH; BB trigger is ~100Hz before dead time

      Run 5886; RICH shared; 1uA; He3 Cell;     1hour; 1M;   30%DT; 3x4 Raster

      ps1=31000,ps2=4,ps3=2,ps4=16777215,ps5=1,ps6=10,ps7=65535,ps8=100

05:17 4th dedicated BB Sieved run;

      Run 5887; BB dedicated;2uA; He3 Cell;     7min;  339K; 17%DT; 3x4 Raster

      ps1=31000,ps2=1,ps3=50000,ps4=16777215,ps5=100000,ps6=1,ps7=65535 ,ps8=100

05:28 BB Sieved run with RICH; BB trigger is ~100Hz before dead time

      Run 5888; RICH shared; 1uA; He3 Cell;     1hour; 1M;   56%DT; 3x4 Raster

      ps1=31000,ps2=2,ps3=2,ps4=16777215,ps5=1,ps6=10,ps7=65535,ps8=100

Figure 1 vertex with cut on electron (preshower & beta) and negative particle

Figure 2 reconstructed momenum

Figure 3 sieve pattern with cut on electron, negative particle and the 3rd carbon foil from upstream

Figure 4 sieve pattern with same cut as above, but it's reconstructed by Gen optics model