1. “Separation of Muons and Doubly Charged Particles using MDT”
K. Belotskiy, O. Bulekov, M. Khlopov, A. Romaniouk, K. Shibaev, Yu. Smirnov
MEPhI 1 1

2. Application of MDT chambers for the doubly charged particles search
The information about charge in the first 8 ns of the signal in MDT drift tube is available in ADC variable.
~20 hits on the track will give a quite good estimation of the dE/dX, which can be used for discrimination of doubly charge particles
The analysis has been done using MuonIDNtupleMakers and MuonIDCommonAnalysis Packages in Rel
Exp DATA :
data10_7TeV physics_Muons.recon.DESD_ZMUMU. (~8K events)
MC Muons:
mc10_7TeV PythiaZmumu_no_filter.recon.ESD.e574_s933_s946_r1831_tid213372_00
(~9K events)
MC QQ-balls:
MC Pythia_Qballs_DrellYan_m500_PDG ESD.pool.root
QQ-balls with M=500GeV and Q=2 have been used as an example of doubly charged particles.
We use Drell-Yan process for generating QQ-balls pairs in Pythia. 200 events with QQ-balls pairs were produced in Rel
The MDT cluster Density for doubly charged Particles has been increased up to 34 clust/mm at the step of digitization 2

3. MDT chambers layout
Station
Number
Chamber
Name 1
bil 2
bis 3
bml 4
bms 5
bol 6
bos 7
bee 8
bir 9
bmf 10
bof
Station
Number
Chamber
Name 11
bog 13
bim 15
eil 16
eel 17
ees 19
eml 20
ems 22
eol 23
eos 24
eis
The big problem for analysis of ADC is the existence of great number of MDT chambers of different types .
The variable “StationName ” is used on
the slides below . The names of chambers
which correspond to station numbers
are shown in the tables. 3

4. <ADC> variations
-1<<1; -1>  &&  >1
~10% variations in <ADC> dependence on Phi
Maximal and minimal values on the left plots correspond to regions of overlapping of the MS chambers.
Probably this is a result of reading of the signal at the one end of the wire..
~7% variations in <ADC>
dependence on Eta
data10_7TeV physics_Muons.
Further we shall consider only region
-1<<1, where variations are small 4

5. Correction of Dependence of <ADC> on Phi
Before correction
After correction
ADCFIT(Phi)
Before correction
CorrectedADC =ADC+(137-ADCFIT(Phi))
After correction
Correction of <ADC> dependence on
Phi decreases RMS of the distribution.
This should improve separation of
muons and doubly charged particles. 5

6. Number of ADC counts vs Rdrift
mc10_7TeV PythiaZmumu
data10_7TeV physics_Muons.
MCFit(R)
DataFit(R)
<ADC> differs strongly for MC Muons and Muons from Exp. DATA! We need additional correction for MC.
Using of dADC=ADC- DataFit(R) variable let to take into account ADC dependence on R.
Mean of the dADC on the track is used for the particle separation.
Correction(R) = DataFit(R) / MCFit(R)
CorrectedADC = ADC * Correction(R) 6

7. dADC vs RMS
MC Pythia_Qballs_DrellYan_m500
data10_7TeV physics_Muons.
Excluding of the hits with max dADC on the track decreases RMS and
improves discrimination of muons and doubly charged particles
dADC increases with RMS growth 7

8. < Number of ADC counts>
No corrections
After applying of all corrections
data10_7TeV physics_Muons.
MC Pythia_Qballs_DrellYan_m500
Applying corrections on Phi and R and truncation of hits with max dADC on the track improves separation between muons and doubly charged particles. 8

9. Mean < dADC > vs P [GeV]
data10_7TeV physics_Muons.
The difference in characteristics of chambers from different Stations of the Muon Sysytem is the other source of <ADC> variations (~7%)
The <ADC> is a bit higher in EC chambers/stations than in Barrel.
The dependence of Mean <dADC> on momentum demonstrates behavior similar to dEdx curve at the same momentum region for muons.
We are planning to study possibility of <dADC> application for dEdx measurements
We are planning to take these variations into account late. 9

10. Conclusions :
Applying of the corrections for ADC dependence on Phi improves separation of the muons and doubly charged particles
It is shown that dADC is effective discriminator for separation of single and doubly charged particles.
Excluding of the hits with max dADC on the track improves discrimination of the muons and doubly charged particles
Adding the Moun System to the identification process will provide powerful instrument for a search of the doubly charged heavy particles.
It is shown that ADC for MC is ~1.5 times less than ADC for experimental data.
Plans:
Investigate possibility of <dADC> application for dEdx measurements.
Construct the combined discriminator for doubly charged particle separation. 10 10 10