R(t) RelationsR(t) Relations

from inclusive MDT tubes from inclusive MDT tubes drift time distributionsdrift time distributions

-- update ---- update --

M.M. BaroneBarone

Software and AnalSoftware and Analyyssiis Meetings MeetingATLAS/FrascatiATLAS/Frascati

LNF -- October 18, 2004LNF -- October 18, 2004

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Use of the inclusive drift time spectrum to determine the R(t) relation,by associating the R position of a track to the corresponding drift time R + t = R(t)R + t = R(t)

The Method

R

muon track

• R is the distance of minimum approach of the muon track to the sensing wire

Watch out!Incorrect R-t association for events wheredelta-rays are produced

• RTRUE(t) = “correct” relation between t and R ( no delta-rays )• Use of RTRUE(t) to determine the distribution

that hypothetically would correspond to the inclusive time distribution

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- The method performs very well: precision < 10 microns using two MonteCarlo samples with different gas mixture

Results from MonteCarlo (Garfield)

Similar excellent performances expected even with real data, provided that the appropriate distribution is used

RTRUE (t) – R(t)

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- Are delta-rays properly simulated by the Garfield program?

Comparison of the delta-ray content:GarfieldGarfield vs X5 dataX5 data (with external tracker)

% of delta-rays

Garfield does not simulate delta-ray production in the tube walls

Use of X5 data to Use of X5 data to determine the determine the

distributiondistribution

Delta rays

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- distribution : from X5

- inclusive time distribution t : from H8

- R(t) = (t)

…………. Our usual procedure, but…Our usual procedure, but…

Procedure

R (mm)

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• Garfield shows that the method is very sensitive to variations of the t0

• Before:Before: t0 and tmax as the starting and final point of the t distribution => very critical and affecting the achievable precision Time window: t0 t0 ≤≤ t ≤ tmax t ≤ tmax

• Now:Now: t0 and tmax values from the FermiDirac fit (bending points of the rising and falling edge resp.) Time window: (t0 – 20ns) ≤ t ≤ (tmax+40ns)(t0 – 20ns) ≤ t ≤ (tmax+40ns)

Integration method

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• R(t) as input for the tracking program (Athena)• our R(t)• R(t) obtained with Calib program

Tracking with Athena

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# of segments <=2

our R(t)

R(t) Calib

R (mm)

resid

ual (

mm

)

PRELIMINAR

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- The method performs very well if the distribution used is appropriate for the sample to be analyzed

- R(t) relation determined applying the distribution from X5 data to the inclusive time spectrum from H8 2004 data:

- tracking highlights remaining problems, especially in the region abs(R)~ 10mm => to be investigatedto be investigated

- Waiting to be able to quantify the number of delta rays in the H8 data we could use the R(t) relation from Calib to determine the distribution once for all

Conclusions

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Supporting plotsSupporting plots

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∆R = R(t+∆t) - R(t)

∆t = 1 ns

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X5 data - RTRUE (t)

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- distribution integral (X5)

- inclusive t distribution integral (H8)

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# of segments – BIL(2 multilayers)

10000 events

216

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R(t) Calib

R(mm) vs t (ns)t (ns)

R (mm)

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residual (mm)residual (mm) vs R(mm)

residual (mm) vs R (mm)

# of segments <=2

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our R(t)

R(mm) vs t (ns)t (ns)

R (mm)

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residual (mm) residual (mm) vs R(mm)

residual (mm) vs R (mm)

# of segments <=2