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Tests of FPS configuration
from the L1 trigger point of vue

Last modified: Mon Sep 13 11:16:10 CDT 1999

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Effect of the size of the overlap region

The overlap between two modules is 1.28cm wide (initial settings
in UPG_GEANT), ie: 2.56 cm for the two edges of the module.

1. Occupancies have been measured with and without the overlap
region

Occupancies in the upstream layers (dijet + 2mbias):
No threshold (plot 1)
L1 threshold (0.3 MeV) (plot 1b)

Occupancies in the downstream layers (dijet + 2mbias):
No threshold (plot 1)

2. e- have been targetted randomly between 101.25 deg.< phi < 123.75 deg, corresponding to the left half of the module 5 , the right half of the module 6, and the overlap between modules 5 & 6.

Effects on the electron trigger efficiencies (e- + 0mbias):

Electron Pt	With overlap	No overlap	Lost events
Pt = 8-20 GeV	529 / 800	525 / 800	4 / 529 (0.8%)
Pt = 20-45 GeV	926 / 1,000	923 / 1,000	3 / 926 (0.3%)

Notes: 9.5% (resp. 17%) of the events have an identified candidate in the overlap region for lower energy (resp. high energy)

3.Effects on di-jet trigger: dijet may fake single or di-electrons candidates. We estimate here the amplitude of the effect by removing the overlap.

Number of selected electrons in dijet in [02-10]GeV:

fake single electron with/without overlap
fake of dielectrons with/without overlap

fake di - electrons

Dijet Pt	With overlap	No overlap	Lost events
[02-10]GeV	263	253	10/263 (3.8+-1.2%)
[10-20]GeV	403	380	23/403 (5.7+-1.2%)
[20-40]GeV	283	272	11/283 (3.9+-1.1%)
[40-500]GeV	151	146	5/151 (3.3+-1.4%)

Thickness of the Lead sheet

Electrons and pions samples have been produced with a lead sheet of 1 Xo.

Adapted Algorithm used for 1 Xo Lead sheet:

T(upstream) = 0.3 MeV

T(downstream) varied from 3 to 10 MeV

Dependence on downstream threshold
e- Efficiency as f(downstream threshold) at 10 and 80 GeV (plot 1)

Efficiency on electrons and comparison 1Xo vs 2Xo Lead

Energy (Pt) (GeV)	10 GeV (Pt=2.5)	80 GeV (Pt=20)
Pb: 1 Xo T = 3 MeV T = 5 MeV T = 10 MeV	72.2+-2.3% 39.5+-2.5% 09.0+-2.7%	94.4+-1.4% 83.6+-2.3% 57.1+-6.6%
Pb: 2 Xo T = 3 MeV T = 5 MeV T = 10 MeV	85.4+-1.7% 54.3+-1.3%	98.3+-0.6% 96.9+-0.9%

Efficiency on PIPLUS and comparison 1Xo vs 2Xo Lead

Energy (Pt) (GeV)	10 GeV (Pt=2.5)	80 GeV (Pt=20)
Pb: 1 Xo T = 3 MeV T = 5 MeV T = 10 MeV	15.9+-2.0% 08.1+-1.5% 02.8+-0.9%	21.2+-2.3% 13.1+-1.9% 07.4+-1.4%
Pb: 2 Xo T = 3 MeV T = 5 MeV T = 10 MeV	09.8+-1.3% 02.3+-0.6%	19.4+-1.8% 11.9+-1.3%

Efficiency on PI0 and comparison 1Xo vs 2Xo Lead

Energy (Pt) (GeV)	10 GeV (Pt=2.5)	80 GeV (Pt=20)
Pb: 1 Xo T = 3 MeV T = 5 MeV T = 10 MeV	26.4+-2.6% 13.2+-1.9% 1.1+-0.7%	61.8+-2.7% 53.6+-2.7% 30.6+-2.5%
Pb: 2 Xo T = 3 MeV T = 5 MeV T = 10 MeV	36.4+-2.1% 15.2+-1.3%	41.9+-3.0% 34.5+-2.9%

Ratio electron/pions at 10 and 80 GeV for 1Xo vs 2Xo Lead

Energy (Pt) (GeV)	10 GeV (Pt=2.5)	80 GeV (Pt=20)
Pb: 1 Xo T = 3 MeV T = 5 MeV T = 10 MeV	3.7 3.9 4.1	2.7 3.1 3.8
Pb: 2 Xo T = 3 MeV T = 5 MeV T = 10 MeV	4.6 3.6	8.2 5.0

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