Analysis

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EG1 run database
run summary
polarization info

Particle Identification

Electron

Cuts

Calorimeter based cuts

The distributions below represent two types of cuts applied to improve the electron particle identification (PID) using a 4 GeV electron beam incident on an NH3 target. The electron calorimeter is segmented into an inner[math]EC_{inner}[/math] and an outer[math]EC_{outer}[/math] region. The total energy absorbed by the calorimeter system is recorded in the variable [math]EC_{tot}[/math]. The momentum ([math]P[/math]) is calculated using the reconstructed track and the known torus magnetic field. The distributions of [math]EC_{tot}[/math] and [math]EC_{inner}[/math] are shown below where both have been divided by the electron momentum and no cuts have been applied.


[math]EC_{tot}\gt 0.2*p[/math]

Without any cuts we have 181018 entries. After using the following cut [math]EC_{tot}\gt 0.2*p[/math] we are getting 127719 entries, which is about 70.55% of 181018.

Etotal P using tot cut.gif
Einner P using tot cut.gif


[math]EC_{inner}\gt 0.08*p[/math]

After the cut on the energy deposited into inner part of electron calorimeter, number of entries decreases by 22%.

Etotal P using inner cut.gif
Einner P using inner cut.gif



Both cuts [math] EC_{tot}\gt 0.2*p [/math] and [math] EC_{inner}\gt 0.08*p [/math]

In case of using the cuts of the total deposited energy and the energy deposited into inner calorimeter number of entries decreases ~36%

Etotal P using both cuts.gif
Einner P using both cuts.gif


summary table

Beam Energy Torus Current Begin Run End Run file used cuts num trig expected # evts
[math]EC_{tot}\gt 0.2*p[/math] [math]EC_{inner}\gt 0.08*p[/math] [math]EC_{tot}\gt 0.2*p [/math] and [math] EC_{inner}\gt 0.08*p[/math]
1606 1500 25488 25559 dst25504_02.B00 64% 49.5% 78%
1606 1946 25560 25605
1606 1500 25669 25732 dst25669_02.B00 64% 49% 78%
1606 1500 25742 26221 dst25754_02.B00 21% 11% 24%
1606 -1500 26222 26359 dst26224_02.B00 4.6% 3% 6.6%
1724 -1500 27644 27798 dst27649_02.B00 4.8% 2.2% 5.9%
1724 1500 28512 28526
1724 -1500 28527 28532
2288 1500 27205 27351 dst27225_02.B00 20.2% 13% 25.6%
2562 -1500 27799 27924 dst27809_02.B00 5.7% 4.6% 8.6%
2562 -1500 27942 27995 dst27942_02.B00 6.1% 4.4% 8.9%
2562 1500 28001 28069 dst28002_02.B00 27.8% 13% 29.6%
2792 -1500 27936 27941 dst27937_02.B00 6.7% 5% 9.9%
3210 -2250 28549 28570
4239 2250 28074 28277 dst28075_02.B00 35.3% 23.9% 40.5%
4239 -2250 28280 28479 dst28281_02.B00 9.1% 9.4% 13.6%
4239 2250 28482 28494
4239 -2250 28500 28505
4239 2250 28506 28510 dst28509_02.B00 29.5% 22% 36%
5627 2250 27356 27364 dst27358_02.B00 33.2% 27.8% 41.3%
5627 -2250 27366 27380 dst27368_02.B00 12.6% 14.8% 19.5%
5627 2250 27386 27499 dst27388_02.B00 33.4% 27.8% 41.4%
5627 965 27502 27617
5735 -2250 26874 27068 dst26904_02.B00 13% 15% 20%
5735 2250 27069 27198 dst27070_02.B00 33.3% 28.8% 42.2%
5764 -2250 26468 26722 dst26489_02.B00 12.2% 14.4% 19.1%
5764 0 26723 26775
5764 -2250 26776 26851 dst26779_02.B00 13.5% 15.5% 20.5%

Cut on the number of photoelectrons

In this case is used a cut on the number of photoelectrons, which is [math]nphe\gt 2.5[/math]. The plots below show the effect of the number of photoelectrons cuts on the Cerenkov distribution. We see that after using cut the number of entries decreases ~40.7%

Nphe before cut.gif
Nphe after cut.gif


Pion

Quality Checks

Rates

Asymmetries