Effect of a combination of a TLT vertex  cut (simulating an MVD vertex cut)  and the present GSLT veto

Last update: 6 march 1998

L.W. Wiggers

What is the effect of high-Et cuts on the effect of the present GSLT and how could a MVD-SLT cut help? I used a gslt-passthrough sample of 1997 (run 25189) to study this:

	all	Etran>2	Etran>5	Etran>10	Etran>25
no further selection	17786	12268	7782	4620	1120
a) passing present gslt veto	9829(55%)	5782(47%)	3914(50%)	2656(57%)	657(59%)
b) having a valid vertex with -30cm<tlt-z<30 cm	2166(12%)	1839(15%)	1236(16%)	791(17%)	117(10%)
c) as b or not having a vertex	13511(76%)	8767(71%)	5318(68%)	2876(62%)	617(55%)
d) both a and b	2157(12%)	1831(15%)	1231(16%)	788(17%)	116(10%)
e) both a and c (preferred cut)	5631(32%)	2352(19%)	1501(19%)	943(20%)	161(14%)

Conclusions:

• the gslt veto is only slightly dependent on e-transverse energies, but becomes less effective at high energies .The reason is, that events with high cal energies have predominantly energy deposits in the fcal but not in the rcal and therefore there is no rcal timing to cut on.
• a tight vertex cut  becomes more effective at high energies and helps to reduce the rate with about a factor two to three!