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A new paper on muon detector performance ------- Discuss the paper content (bepo + roberta). Martellotti 24-09-2010. Paper content (1) LHCb muon detector calibration and performance (after HV optimization) with collisions tracks (field on – high p muons)

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A new paper on muon detector performance ------- Discuss the paper content (bepo + roberta)

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A new paper on muon detector performance discuss the paper content bepo roberta

A new paper on muon detector performance

-------

Discuss the paper content

(bepo + roberta)

Martellotti 24-09-2010


A new paper on muon detector performance discuss the paper content bepo roberta

  • Paper content (1)

  • LHCb muon detector calibration and performance (after HV optimization) with collisions tracks (field on – high p muons)

  •  Do not treat in detail MuonID and TRIGGER

  • Detector setting up

  • optimization of the chambers working point

  • time alignment

  • Detector performance

  • space alignment

  • cluster size

  • efficiency of the detector


A new paper on muon detector performance discuss the paper content bepo roberta

Content (2)

Same as in previous slide with an “Historical approach” (this approach could be used in the introduction to explain the work)

# A first setting up of the detector was performed in 2009 with hardware and software tools and the use of cosmic rays (ref). The settings chosen allowed to reach an adequate performance of the detectors to run the system with the first collisions with a reasonably good efficiency.

# here we briefly report on the status of the detector at the time of very first collisions

# we describe the subsequent improvements in the detector settings (noise, thr, HV,…) discussing the effects (…time shift…)

# we describe the actions taken and procedures to improve the detector performance (new time alignment…)

# we assess the “final” performance of the system with high momentum muons from collisions


A new paper on muon detector performance discuss the paper content bepo roberta

  • Let’s go through possible CHAPTERS

  • to help discussion on

  • - paper content

  • results already established

  • work to be done


A new paper on muon detector performance discuss the paper content bepo roberta

The LHCb muon system

A full description of detector is needed once again ?

Probably yes. In the cosmic paper we started with a very short description and we were obliged to extend…


A new paper on muon detector performance discuss the paper content bepo roberta

  • Track reconstruction & Data sample

  • # Are the track reconstruction algorithms different for

  • different analysis ? Is it relevant ?

  • # Data sample needed for analysis to be completed may be different for different analysis:

  • space alignment : new analysis needed. There is an “old stripping” of min. bias with “loose” muons that should be OK.

  • time alignment : data already analyzed. Old HV data for equalization inside regions + new HV - TAE mode (scanning).

  • Do we need new analysis / new data sample for the paper?

  • cluster size : new analysis needed with single BC new HV data. Statistics needed?

  • - efficiency : we need a new high statistics sample (new HV):

  • Do we use downscaled minimum bias or make a selection of “non triggering” muons in triggered events ?

  •  Decision / Preparation of high statistics sample


A new paper on muon detector performance discuss the paper content bepo roberta

  • Setting up of the detector

  • Status of the detector settings and performance at the beginning of LHC operation

  • - Briefly report on the hardware and software work done in 2009 to set up the detector for the first collisions (ref cosmic paper)

  • - recall the initial status of settings (and initial performance)

  • Do we report on the efficiency measured with the first 2009 collisions ???

  • (if not, I would unify this paragraph with the next one)


A new paper on muon detector performance discuss the paper content bepo roberta

  • Setting up of the detector

  • 2) Optimization of the chambers working point

  • principles - method - setting chosen :

  • noise level, threshold, optimized HV.

  • Explain the effects of changing settings (HV) on detector performance (time resolution and time alignment, cluster size, efficiency)

  • Are there other significant detector improvements to mention

  • (dead channels recovered, actions taken for GEM, …) ?


A new paper on muon detector performance discuss the paper content bepo roberta

Setting up of the detector

3) New time alignment

  • # 1) equalization among channels of the same region

  • Collision data with old HV have been used (much higher statistics available w.r.t. cosmics in the inner regions)

  • # 2) optimization of the time offset per region with new HV (time-scanning data in TAE mode)

  • shall we give chamber time resolution ? (problem with the

  • distribution tails. I would avoid discussing again TDC) 

  • explain the “timing efficiency” in 25ns measured with TAE

  • events as a direct consequence of the time resolution.

  • report about checks done, M1, dead channels …other items?

  • Is further analysis needed for the paper ? On which data ?

  • (check with muons matched to high momentum tracks ?)


A new paper on muon detector performance discuss the paper content bepo roberta

Detector performance

1) Space alignment

- alignment done with trigger unbiased muons (from min bias events) matched to high momentum tracks

- We should conclude if hardware alignment is satisfactory (yes it is) and if further (minor) improvement is possible and useful.

It would be good to have an (even rough) estimate of the effect of misalignment on Trigger efficiency.

# Global alignment with OT must be done.

The “old” muon data sample from min bias is OK but probably we must re-run the events (tracking software modified) (*)

# Alignment with MUON stand alone if possible should also be done (it is a complementary check…)

(*) The present OT alignment should be good enough for us (Select field on – high momentum tracks) ?


A new paper on muon detector performance discuss the paper content bepo roberta

Detector performance

2) Cluster size

Give CS along X (or X,Y separately).

Report the CS for 5 stations 4 regions (average value and CS vs angle)

Use events of single BC with final HV settings

Select hits associated to high momentum tracks (for other selections see Walter – ambiguities, chamber edges….)

Data sample ? Statistics needed ?

Explain the expected contribution from geometry…

Explain the relevance of CS :

show dependence on HV, stress the importance to have reasonable CS values as a check of a safe chamber working point, explain the (limited) effects of CS on Trigger


A new paper on muon detector performance discuss the paper content bepo roberta

Detector performance

3) Efficiency

Can we have efficiency vs momentum (statistics) ?

If not give the efficiency measured with “high energy” muons

Compare with “timing efficiency” and discuss other contributions.

Try to disentangle detector efficiency and acceptance effects.

Geometrical acceptance - Hermeticity - Fiducial volume…

Compare with MC

Data sample ?


A new paper on muon detector performance discuss the paper content bepo roberta

Some material for discussion with

some personal comment


A new paper on muon detector performance discuss the paper content bepo roberta

Setting up of the detector

Optimization of HV

Time alignment


Multiplicities at hv optimal vs 2650v settings

Multiplicities at HV_optimal.vs.2650V settings

Effect of HV on cluster

Show CS versus HV measured in lab?

Region

M1 M2 M3 M4 M5

Ratio of the average number of Pads (red) and Clusters (blue)

HV_optimal/2650V for noTAE events (time centering for HV_optimal)

  • ~ larger DV corresponds to lower ratio (M2R1,M3R1),

    also Clusters change, even if less than Pads

Alessia, Rob 23 apr


A new paper on muon detector performance discuss the paper content bepo roberta

timing

Giacomo 16 apr


A new paper on muon detector performance discuss the paper content bepo roberta

Detector performance

1) Space alignment


A new paper on muon detector performance discuss the paper content bepo roberta

Trigger efficiency - Y misalignments

In the Y intercept of fitted track with plane Z=0 we see

A spike of tracks with all Y pads perfectly aligned and

many tracks with not aligned pads  trigger inefficiency

Trigger fails for

Multiple scattering

Punch through

Decays with large kink

&

Detector misalignments

1 m

Stefania muon meeting 23-04-2010


A new paper on muon detector performance discuss the paper content bepo roberta

  • How to spot possible trigger losses due to Y misalignment with stand alone alignment

  • Muon ID with ISMUON (or other equivalent algorithm)

  • 2) Select tracks with only 1 hit in M3 (or a cluster of hits having the same Y)

  • 3) Assume the projective slope IP-hitM3 (do not fit θYZ)

  • 4) Consider the hits “belonging” to the track and plot

  • ΔMi = YMi – YMiM3 (projective-extrapol from M3 to Mi)

  • 5) Look separately at different regions and side A-C

  • (eventually consider only tracks crossing M3 in the inner pads of the chambers in regions R1, R2)

  • # For tracks crossing the same region in Mi and M3

  • Δ = 0  good alignment

  • Δ = ± 1 pad  physical misalignment (Mult Scatt…)

  • or detector misalignment

  • If Δ ≠ 0 for M1,M2  no L0mu trigger


A new paper on muon detector performance discuss the paper content bepo roberta

YM2-YM3

DY = ± ½ pad

When tracks

change region

DY = ± 1 pad

Mult Scatt or

misalignment

R2

R3

R4

R1

Stefania


A new paper on muon detector performance discuss the paper content bepo roberta

Y station alignment w.r.t. M3

when track change region

M1

R1

R2

R3

R4

M3

Y

M3

M1

M3

M1

X

± 1/4pad± 1/2pad

rare frequent

YM1-YM3 =

R2

R3

R4

Z

M3

WITH MAGNET ON TRACKS

OFTEN CHANGE REGION

A track in M1R3

can easily go in M3R4

rarely in M3R2

M1

X


A new paper on muon detector performance discuss the paper content bepo roberta

+½ pad

YM1-YM3

R2

R3

  • DY = ± 1 pad

  • Mult Scatt

    or

  • misalignment

-½ pad

R2

R3

With uniform track

distributions

+1pad

Misalignment

(n+1-n-1) / n0

-1pad

Stefania


2 cluster size

2) Cluster size


A new paper on muon detector performance discuss the paper content bepo roberta

Walter: COSMICS - CS versus θxz

Log.pad

X (cm)

pys.pad

/ log.pad

0.7

0.6

1

1

1

2.9

1

3.1

w

w

Wire

Cath

r/o

2

1

1

1

1.3

1.4

6.2

1

5.8

1

R2

w

w

2.5

1

2.7

1

12

2

4

2

2

12

R3

23

4

25

5

1

5.4

1

4

8

2

R4

w

w

w

w

w

M4

M2

M3

M5

M1


A new paper on muon detector performance discuss the paper content bepo roberta

  • MY COMMENTS:

  • All regions have reasonable values but M2R4 and M3R4

  • Remember that CS are measured in PAD unity

  •  smaller values are expected for larger pads

  • For wire pads we don’t expect large Cluster Size:

  • there is no “induction” and we never measured so high values with cosmics in Lab

  • Compare M2R4 M3R4 with M1M4M5-R4 that have small

    values as expected

  • M2R4 M3R4 should be much smaller than M2R3 M3R3

    (having half pad size and induction)

For collisions 2010 with optimized HV Giacomo reported results compatible with Walter cosmics old HV for all the stations but M2R4, M3R4 where he finds smaller values


A new paper on muon detector performance discuss the paper content bepo roberta

COLLISIONS – no angular cut – optimized HV

different definition of CS counting both X and Y adjacent hits

(angular dependence neglected - is not alwais negligible)

Giacomo 21-05-10


A new paper on muon detector performance discuss the paper content bepo roberta

Giacomo


A new paper on muon detector performance discuss the paper content bepo roberta

collisions-25ns CS versus θ (θxz woud have been better *)

Giacomo

* θ can be dominated by θyz that is not significant for CS


3 efficiency acceptance

3) Efficiency / acceptance


M stations efficiency 2009 data mc

search window M1

to measure the efficiency of M2, M3 and M4

require the M5 hit in

Dx = 5 (padx + 6. x errx)

Dx = 4 padx

, Dy = 2 pady

Dy = 3 (pady + 4. x erry)

to measure the efficiency of M5

require the M4 hit in

search window M4

search window M3

search window M5

search window M2

Dx = 4 padx

, Dy = 2 pady

Dx = padx + 6. x errx

Dx = padx + 7. x errx

Dx = padx + 6. x errx

Dx = padx + 6. x errx

Dy = pady + 4. x erry

Dy = pady + 4. x erry

Dy = pady + 4. x erry

Dy = pady + 5. x erry

efficiency (p > 8 GeV/c)

M1 M2 M3 M4 M5

~80% of the selected Long Tracks are m’s

m stations efficiency 2009 Data/MC

  • Distinguish between detector inefficiency and geometrical effects (acceptance at detector borders and non hermeticity)

  • Comparison with MC

  • where the detector efficiency is plugged in and well known

  • Acceptance effects for M1, M5

    (fiducial volume...)

Muon Meeting – 23/4/2010 P. de Simone 5


A new paper on muon detector performance discuss the paper content bepo roberta

Alessia 19/05/2010

Monte Carlo


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