Analysis

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.

[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%.

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%

summary table

Beam Energy	Torus Current	Begin Run	End Run	file used	cuts
					[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%
5764	-2250	26468	26722	dst26489_02.B00	12.2%	14.4%	19.1%
5764	0	26723	26775	dst26779_02.B00	13.5%	15.5%	20.5%
5764	-2250	26776	26851
5735	-2250	26874	27068	dst26904_02.B00	13%	15%	20%
5735	2250	27069	27198	dst27070_02.B00	33.3%	28.8%	42.2%
2288	1500	27205	27351	dst27225_02.B00	20.2%	13%	25.6%
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
1724	-1500	27644	27798	dst27649_02.B00	4.8%	2.2%	5.9%
2562	-1500	27799	27924	dst27809_02.B00	5.7%	4.6%	8.6%
2792	-1500	27936	27941	dst27937_02.B00	6.7%	5%	9.9%
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%
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%
1724	1500	28512	28526
1724	-1500	28527	28532
3210	-2250	28549	28570

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.