comparison of different chamber configurations for the high luminosity upgrade of M2R2

G. Martellotti - LNF - 13/03/2015

Roma1 + Alessia

1) Bi-poissonian distribution of hit number NThe average number of hits per event is <N> = μ ωμ = average number of interactions per BC (1.7 in 2012 data)ω = average number of hits per interaction in the region under studyThe distribution of N is the convolution of 2 Poissonian distributions and in the first one P(0) is eliminated to take in to account that BCs with 0 interactions are not acquired2) CLUSTER SIZE is taken into account (presently only CSX is considered)

FURTHER STEPS that should be done - Realistic hit spatial correlation (‘’Alessia’’)- Correct efficiency calculation

SIMULATION

mu =1.7At the same rate (per second) in the acquired events I have more hits in the TS (0 interactions not acquired)

mu =7.6At the same rate I have less hits in the TS - The ghost fraction depends only on the hit number.

M2R2 (as it is now) at 40 MHz

Rate of particle hits (KHz/cm2)

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Effect of bi-poissonian (and zero interactions probability)

Particle hits

Reco hits

CLUSTER simulation

M2R1 PadLog=0.63x3.1 STRIPWIR=0.63x25 STRIPCAT=3.8x3.1M2R2 PadLog=1.25x6.25 STRIPWIR=1.25x25 STRIPCAT=15.0x6.25 4 x CATphys=7.5x3.1M2R3 PadLog=2.5x12.5 STRIPX=2.5x50 STRIPY=15.0x12.5M2R4 PadLog=5.0x25.0

For the moment in the simulation I assumed Clusters only along X

No CS simulated.Assumed uncorrelated hitsN part = N hit

CS for particles in the TS simulated Not considered contributions from contiguous TS

contributions from particles hitting contiguous TS

32% CLSX=148% CLSX=220% CLSX=3- NO CLSY

Rate of particle hits (KHz/cm2)

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CS assumed

Increasing CS reduces the rate of particles in the TS and ghost fraction

Increasing CS increases the contribution of hits and ghosts due to contiguous TS

M2R2 (as it is now) at 40 MHz

M2R2

Can we assume that, at these low rates, ghost fraction is negligible ?

Rates of reconstructed hits in 2012 (by Giacomo)

Rates at high luminosity are extrapolated from 2012 data

32% CLSX=148% CLSX=220% CLSX=3- NO CLSY

Estimate of GHOST % in 2012

Particle hits / Reco hits = 0.97 for minimum= 0.90 for average= 0.85 for maximum

M2R2

Also at low luminosity (2012) the simulated ghost fraction is not negligible

The ghost fraction on data appears to be significantly larger due to the large spatial correlations (See ‘’Alessia’’)

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Assuming Cluster Size:

Rate of reco hits (KHz/cm2)

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Particle hits

Reco hits

Hit number distribution Comparison data - simulation

DATA 1 PVplot is zero suppressed - Zeros are ~ 93%

M2R1Simulation1 PV

Simulation4 PVZeros <<93%

ALESSIA

Average hit number as a function of nPV measured in 4 crowded chambers of M2R1

The hits found for nPV=7.6 correspond to ~ 2 Pad /TS

PV number

ALESS

IA

PARTICLE RATE at luminosity = 2x1033

Minimum Average Maximum M2R2 15 47 82

The ghost fraction in 2012 is larger The rates of particle-hits

extrapolated at high luminosity should be even smaller

The ghost fraction even larger

Absolute values are still quite uncertain.But this is not so critical in the comparison of different configurations

Rates ghost subtracted (simulation)

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comparison of different M2R2 configurations

M2R2 as it is NOW TS =375 cm2 - 48 log.ch. = 12 wir(X) * 4 cath(Y)Area wire pad = 31.3 cm2 Area cathode logical channel = 93.6 cm2

composed of 4 phys. Channels 2 Ored on FE, 2 on IB

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Trigger Sector

Logical cath. channel =4 Phys. Ch.

wire channel GHOST FRACTION

at 80 kHz/cm2

~28%

48+32 = 80 readout channels per chamber from FE (64 from IB)

A

Rate of particle hits (KHz/cm2)

M2R2 HALF TS =375/2 cm2 - 24 log.ch. = 6 wir(X) * 4 cat(Y)Area wire pad = 31.3 cm2 Area cathode logical pad (1/2) = 46.8 cm2

Cathode logical channels composed of 2 vertical phys. chann. SAME LOGICAL PAD AS NOW

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Logical cath. channel = 2 phys. ch.

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GHOSTS FRACTION at 80 kHz/cm2

reduced to 16%

48+32 = 80 readout channels per chamber

Same CARIOCA Inefficiency Reduced DIALOG ineff. w.r.t. configuration A

B

Rate of particle hits (KHz/cm2)

M2R2 TS =375/2 cm2 - 24 log. Ch - X, Y = 3 wir, 8 cat Area wire pad (x2) = 62.6 cm2 Area cathode pad (1/4) = 23.4 cm2

LOGICAL PAD area same as now, shape changed.

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Logical cath. channel

Logical wire channel =2 phys ch.

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GHOST FRACTION reducedAssuming the same CS 15.5%Reducing CS (guess) 14.2%

Same CARIOCA Inefficiency DIALOG inefficiency further reduced

24+64 = 88 readout channels per chamber

C

Rate of particle hits (KHz/cm2)

Solution C versus solution B • ( 88 vs 80 readout channels)• Similar inefficiency • CS and Ghost fraction (slightly) reduced • Better shape possible improvement of FOIs for medium-high momentum muons FOI can be reduced by a factor 2 reducing MisID without loosing in MuID efficiency

B CM

atteo

M2R2 TS =375/2 cm2 half area - 48 log. Ch. X, Y = 6 wir, 8 cat Area wire pad = 31.3 cm2 Area cathode pad (1/4) = 23.4 cm2

LOGICAL PAD area 1/2 (and the occupancy per logical pad also 1/2)

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wire channel

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GHOST FRACTIONslightly higher19% at 80 kHz/cm2

48+64 = 112 readout channels per chamber

Same CARIOCA Inefficiency DIALOG inefficiency further reduced

D

Rate of particle hits (KHz/cm2)

Reading only all physical cathode pads

NO GHOSTS - Too high occupancy per pad 8.25% - Too large X side to build up a convenient FOI for high momentum muons

64 readout channels per chamber

P M2R2 Cathode Pad Detector 192 pads per chamber 1) Pad (=present logical pad) = 1.25 x 6.25 = 7.8 cm2 (48 x 4 pads/chamber) 2) Pad (=solution D - 2X, 1/2Y) = 2.5 x 3.12 = 7.8 cm2 (24 x 8 pads/chamber) • No ghosts at all • Much higher efficiency • The second solution is better (FOIs for MuID)

1) 2)

CONCLUSION: a cathode pad detector is certainly convenient

A new topic

AND/OR

Two different definitions: MC : % of penetrating tracksData : reconstructed hits (crossings) AND/OR

We cannot assume that all the tracks not giving the AND are ‘’single gap’’ tracksThey can be ‘’large angle’’ tracks

Big effect on pad efficiency evaluation

Revise efficiency calculations

In the DIALOG the AND is first performed between the physical channels of the two layers and only after the OR of adjacent channels the AND/OR measures the correlation between physical channels, neither logical channels nor logical pads

DIALOG logical channel generation map

• We have the OR of two layers (pad of both layers must be inefficient to have an inefficiency) the inefficiency is essentially due to the fraction of correlated hits due to penetrating tracks• If ROR is the rate in the Giacomo table, the rate on single layer is R1L = ROR (1+fc)/2 where fc is the fraction of correlated hits• Layer inefficiency is Ineff1L ~ δeff *R1L where δeff is the effective dead time• The OR inefficiency is fc* Ineff1L OR inefficiency ~ fc* Ineff1L

• Now to build up the logical pad we perform the AND of X, Y stripes• AND inefficiency = ineffX + ineffY + ineffX *ineffY

The ‘’hit correlation’’ measured from the AND/OR ratio for logical pads cannot be assumed as correalation for logical channels X and Y (neither for logical channel composed of the OR of 2 or more adjacent physical channels)Large angle tracks don’t giving AND because they are hitting a different physical channel X, can have correlated hits in the logical channel Y

The inefficiency has been significantly underevaluated in • regions where logical pads are the crossing of physical X,Y channels

(M23R12)• or/and in regions where logical pads are the OR of adjacent physical

pads

• AND/OR ratio must be evaluated on data separately for X and Y channels.- The difference between the two measurements will give us an idea of

the impact of ‘’large angle tracks’’ • When beam is on, we have to measure AND/OR switching off one gap

SPARES

Penetrating tracks cross 4 gaps. After crossing the first gap, they can hit next gap in the same pad (small angle-pad centered tracks) or not (large angle-peripheral tracks). - Here pad is the logical pad or the logical channel (X,Y) in M23R12

Lets call:S = fraction of single-gap tracks in each gap P = fraction of penetrating tracks crossing 4 gaps F = fraction of P crossing one pad in a gap and a different pad in the contiguous gap• The hit rate on the first gap is RG = K(P + S). FP tracks of this gap will give a new hit in the next gap The OR rate of 2 contiguous gaps is R2G = K(P(1-F)+2FP+2S) = K(P+FP+2S) When going from gap 2 to gap 3, by definition of F, again a fraction F of P tracks (not necessarily the same tracks previously jumping pad) gives a new hit in the third gap The OR rate of 3 contiguous gaps is R3G = K(P(1-F)+3FP+3S) = K(P+2FP+3S) The rate of the OR of 4 gaps is R4G = K(P(1-F)+4FP+4S) = K(P+3FP+4S)

• If the logical pad is composed by 1 physical pad (Nph =1) the rate measured with the And is RAnd = K(1-F)P. Let’s call Corr = RAnd/ROR

The rate on the single FE to calculate the effect of CARIOCA dead time is R1FE = R2G = K(P + FP + 2S) = ROR (1+ Corr)/2The inefficiency of a straight μ Inefμ=InefPAD(Corr+InefPAD(1-Corr)) ~ InefPADCorr

• If the logical pad is composed by Nph physical pads R1FE > ROR (1+ Corr)/2(the AND measures only the penetrating tracks hitting in the next gap the same physical pad, not the same logical pad) To evaluate correctly the dead time inefficiency, we should know the % of inclined tracks. For M23R12, it is also crucial to know separately Corr for X and Y while presently correlations were measured for the logical pad.The small correlation measured is probably due to the small wire strip size, while correlations for cathodes could be much higher (and their inefficiency much higher) % of single gap tracks S is much smaller - inefficiency is underevaluated

2 Pys/LOR

2 Pys/LAND

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OR AND1 00 01 00 00 01 00 01 01 01 01 01 01 10 00 01 1

OR/AND of the 2 layersOR =10, AND=2 f = AND/OR = 2/10

OR/AND of the 2 layersOR =8, AND=2f = AND/OR = 2/8

CHAMBER 1phys.ch.=1log.ch.2phys.ch.=1log.ch.

Hit rate = ROR

ROR =10R1FE = 6 = ROR (1+f)/2

Hit rate = ROR

ROR =8R1FE = 6 ≠ ROR (1+f)/2 = 5

This is because the AND is always performed on the single Phys. chann. Inclined tracks can

contribute to 1 hit in the OR and not to the AND

to evaluate correctly the dead time ineffic. I should know the % of inclined tracks

Separate readout of all phys channels in a layer

2 phys channels are Ored in each layer