CLC Roberto Rossin Bologna CLC seminar, 03/14/2006 Measuring CDF’s Run II Luminosity Introduction Tevatron Luminosity measurement techniques The CLC

Roberto RossinRoberto RossinBologna CLC seminar, Bologna CLC seminar,

03/14/200603/14/2006

CLC

Measuring CDF’s Run II Measuring CDF’s Run II LuminosityLuminosity

Introduction Tevatron Luminosity measurement techniques

The CLC Detector Gas, cones and light collectors PMTs Mechanical design

Simulation Event generator Detector

Test beamPerformance

CDF luminosity measurementSummary

Roberto Rossin for the CLC group

University of Florida


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Intro


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Collider Beam Collider Beam LuminosityLuminosity

Collider Beam Collider Beam LuminosityLuminosity

Lttppn )(events) top( EfficiencyAcceptanceBR

diameter) beam 100(~ cm 103~

spacing)bunch sec (132 MHz 2~

(36) ringin bunches ofnumber

) 104~(nch protons/bu-anti

) 103~(nch protons/buN

242

0

10

11p

nf

B

N p

Total Lum:

=Np Np Bf 0

42L

Instantaneous Luminosity:

~ 2x1032 cm-2s-1

(Run IIa goal)

dt L L goal) IIa (Run -1

fb 2 ~


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36x36 Bunch Structure36x36 Bunch Structure


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Run II Tevatron LuminosityRun II Tevatron Luminosity


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CLC Run II Integrated Run II Integrated LuminosityLuminosity


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Run II: now and in 2009Run II: now and in 2009

980 GeV, 36 x 36

Parameter Now 2009 _

Initial Luminosity 120-160 270 E30 cm-2 s-1

Integrated Luminosity 16 28 pb-1/week

Tot. Int. Luminosity 1.6 4.8-5.4 fb-1

Protons/bunch 235 300 E9

Antiprotons/bunch 35-50 75 E9

Proton emit. (95%,norm) 16 16 mm-mr

Pbar emit. (95%,norm) 11 8 mm-mr

Beta @ IP 0.28 0.28 meter

Hourglass factor 0.58 0.58

Peak Pbar Production Rate

16.6 >20 E10/hour


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Luminosity Detector in Run IILuminosity Detector in Run II

Operate at: L ~2*1032cm-2sec-1 7ppbar/b.c.

Run I Run II

L

Measure instantaneous and integrated luminosity for CDF

and Tevatron in real-time (~ 1 Hz),

standalone, and offline for physics

delivered and live luminositybunch by bunch luminositykeep good precision at high

luminosity: < few % Measure z profile of collisions Provide a minimum bias

trigger for CDF. Diffractive trigger NEW: veto for b-physics

triggersLinear, robust, and with many handles for very high Luminosity

CLC

Finding room in CDF IIFinding room in CDF II

Plug Upgrade

Central Muon Upgrade

Central

Muon

Extension

Silicon Vertex

Detector

Forward Muon Upgrade

Low Beta Quad Low Beta Quad

Low Beta Quad Low Beta Quad

Run I

Run II

Intermediate

Muon System

plug

beam-beamcounters

10o

3o


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Pointing Gas Cherenkov Pointing Gas Cherenkov CountersCounters

Pointing Gas Cherenkov Pointing Gas Cherenkov CountersCounters

Sensitive to the right particles! Much light for particles from interactions Little light from secondaries and soft

particles

• Cherenkov thresholds

• Shorter paths Not too sensitive to particles from back

(halo) Excellent amplitude resolution

Count # hits and # particles No saturation nice linearity

Excellent time resolution Distinguish # of interactions by time

Robustness Radiation hard / low mass

Disadvantages: Needs gas system

New idea, more interesting....


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CLCTechniques for Luminosity Techniques for Luminosity

measurementsmeasurementsTechniques for Luminosity Techniques for Luminosity

measurementsmeasurements

Use a relatively well known, copious, process: Inclusive inelastic p-pbar cross-section

large acceptance at small angles

Lf in

• µ = avg. # of interactions/b.c.

• f = frequency of bunch crossings

• = tot inelastic cross-section

• L = inst. luminosityin

Use a good estimator Measure the fraction of crossings with p-

pbar interactions (Run 1 “rate” technique)• Use: prob. of no int.

Direct counting # of p-pbar interactions Counting particles Counting time clusters

Cross-calibrate with rarer, clean, better understood process:

Need full understanding of tracking, particle-id, missing-Et,, trigger, NLO, bcknds etc. Useful for integrated lum abs. normalization

,lepW

det ectorBC inf L

Use dedicated detector:

eP0


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60.40 (1.40)

81.90 (2.30)

CDF extrap.@ 2.0 TeV

55.92(1.19) 2%

60.33 (1.40) 2%

71.71 (2.02)

80.03 (2.24)

E811Exp.

CDF meas.

@ 1.8 TeV

Process (mb)

8%in

tot

The total pp cross sectionThe total pp cross section

Elastic Scattering Single Diffraction

M

Double Diffraction

M1 M2

Hard Core

Proton AntiProton

PT(hard)

Outgoing Parton

Outgoing Parton

Underlying Event Underlying Event

Initial-State Radiation

Final-State Radiation

“Hard” Hard Core (hard scattering)

Proton AntiProton

“Soft” Hard Core (no hard scattering)

+ ++

+


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CLC Luminosity methodsLuminosity methods

Measure energy deposited on CLC Particle counting Count # of channels above threshold Hit counting (Implemented)Count empty events Zero counting (main method so far) Count # of clusters in time Time clusters counting

Need to calibrate detector.. Need to calibrate detector.. estimateestimate

which accounts for limited which accounts for limited coverage and efficiencycoverage and efficiency

From simulationsNeed all relevant material in CDFNeed “correct” generator…

From real dataW’s, Z's, J/'s yields

Particle counting with thresholds

Hit counting

Zero counting

Particle counting


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“particles” hitsZero bias data SimulationPerfect linearity

expected L in Run II

Particle counting – Hit counting Particle counting – Hit counting methodsmethods

1P

P

in

BC

N

NfL

= avg. # particle for a single p-pbar interaction.

= measured avg. # particle/bunch crossing

1PN

PN

1H

H

in

BC

N

NfL

= avg. # hits for a single p-pbar interaction.

= measured avg. # hits/bunch crossing

1HN

HN

Measured at low luminosity from 0-bias data

Hit Counting

Particle Counting


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CLCParticle counting – Hit counting Particle counting – Hit counting

methodsmethods

Hit Counting

Particle Counting

Advantages:No saturation @ high LLinear with physical backgrounds

Disadvantagesgain/gain= L/L

Advantages:Less sensitive to gain/gain

DisadvantagesNot linear with physical backgroundsSaturation @ high L

Define a collision { >0 hits in E} .and. { > 0 hits in W} with amplitude > Ao

• Online has fixed thresholds• Offline we can normalize to single particle peak (spp)


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Threshold

Luminosity with zero counting methodLuminosity with zero counting method

Zero Counting (empty crossing)

Amplitude (p.e.)

single interaction

five interactions avg.

1 part.

1 part.

2 part.

100 p.e.secondaries

primaries

Measure the average of the poisson distribution by measuring the 0 bin0 bin.

An empty crossing is a BC without E–W coincidence in CLC.

eP )(0

Advantages:Less sensitive to gain/gain Formula is correct at every L

DisadvantagesNot linear with physical backgroundsStatistically limited at very high L


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Luminosity counting time Luminosity counting time clustersclusters

Time clusters

interaction time

~100ps

=1.4ns0

1

2

3

4

1 2 3 4 5

counter arrival times

Measure the number of p-pbar interactions using

precise timing


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Detector

design

CLC

CDF II cross-sectionCDF II cross-section

0

.5

1.0

1.5

2.0

0 .5 1.0 1.5 2.0 2.5 3.0

300

SOLENOID

= 1.0

= 2.0n

= 3.0n

n

m

m

END WALL HADRON CAL.

CENTRAL OUTER TRACKER

COT Endplate

ISL

SVX II

Electronics

(m)Z

Plug EMPlug Had.

CLC

CENTRAL CALORIMETER

10o

3o


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CLC CLC Mechanical CLC Mechanical DesignDesign

48 counters/side3 layers with 16 counters eachrapidity coverage 3.7< <4.7Isob pressure: up to2atm


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CLC CLC location in CDFCLC location in CDF


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CLC CLC DesignCLC Design


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Cherenkov radiation cos = 1/( n) Npe = No L <sin

No = 370 cm-1 eV-1 col(E)det(E) dE

col - light collection efficiency

det - PMT quantum efficiency

Pions > 2 GeV & Electrons > ~9 MeV

Isobutane @ 1atm n=1.00143 =3.1o

sin col>~0.80x0.80 = 0.64 det(E) dE ~ 0.84 (quartz

window) No ~ 200

Np.e.~110 (L=200cm)

Cherenkov Counters – Cherenkov Counters – prototypeprototype

Cherenkov Counters – Cherenkov Counters – prototypeprototype

particleL

PMT

mylar cone light collector

window

cm 5~

gas

1 / nLight emitted if UV dominated


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CLC Gas & conesGas & cones

Gas: Isobutane at low (< 2atm) pressure Higher pressure:

higher refraction index higher amount of light higher Cherenkov angle more reflections

Cones Aluminized mylar:

2 x 0.1 millimiters thick 60 nm aluminum layer MgF2 coated reflectivity for Cherenkov light > 90%

Inner Layer Middle Layer Outer Layer

d 0.831 in 0.854 in 1.211 in

D 1.175 in 1.653 in 2.318 in

L 43.498 in 71.813 in 70.610 in

0.45 degree 0.64 degree 0.90 degree


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Aluminized Mylar cones - designAluminized Mylar cones - design

2cos)(

/2

2/

minmax

minmin

c

c

RRL

dR

Light collector (Al)

cone cap2 layers; 0.1 mm each; 60 nm Al coating

(rad hard)

50 nm Al + 50 nm MgF2


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Light collectorsLight collectors

Light collectors Used to collect light onto the face of the

PMT Aluminum with conical shape

optimized for maximum light collection efficiency

inner: single cone middle & outer: bi-cone (10° and 14°). For

large collectors bi-cone has higher efficiency and uniformity. Give a less divergent light beam

Polished to optical quality; coated with 50 nm Al and 50 nm MgF2.

Gap between collector and PMT window allow to hide PMT deep inside magnetic shield. L/D > 1 in order to protect PMT against the

magnetic field (L=distance between shield edge and PMT, D=shield diameter)


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CLC Light collection efficiency Light collection efficiency simulation simulation

Cone+coll efficiency VS collector-PMT gap

Collector efficiency VS photon angle

gap = 0, 5, 10, 15 mm

Collector eff:bi-cone single cone

Total eff:bi-cone single cone

Cone eff VS photon position


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Geometrical constraints ~ 25 mm diameter (all layers…)

Larger doesn’t fit Smaller requires large angle

collector (losses)

Performance Quartz window

UV transparent Rad hard Thin

Less light Better timing resolution

Timing resolution Sub 100 ps resolution

PMT choicePMT choice

R5800Q Hamamatsu10-stage / 106 gain

0.8 mm concave-convexquartz window25 mm x 60 mm1.7 ns rise-time

~12 ns pulse width

PMT

R5800Q parameters

mm 25

cathode mm

21

N. of stages

10

Q.E.% 27

Voltage, kV 1.8

nominal gain, 106

2.0

dark current, nA

2

dark noise, kHz

6

rise time, ns

1.7


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CLC systemsCLC systems

CDF

CLC East CLC West

CCCooolllllliiisssiiiooonnn HHHaaallllll CCCooouuunnntttiiinnnggg///CCCooonnntttrrrooolll RRRoooooommmsss

CLCFront EndElectronics

Crate

CLC OnlineLumi DAQ

CLC LEDCalibration

System

HV CAENSY527/A932N PC

CDF TriggerSupervisor

CDF DAQ

Ethernet toTevatron

70 m coax cable

70 m coax cable

70 m coax cable

Min. BiasCoincidence

Unit CDF Level-1trigger

Gas System

CLCLuminosity Readout & Luminosity Readout &

Information FlowInformation Flow

CLLD

CLLD

OFFLINE ONLINE


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CLC Calibration Calibration systemsystem

white Tyvec

quartz fibers

• Green-blue bright LED from Ledtronics• Quartz fiber + Tyvec reflector• Pulse generator @ 8 V x ~40 nsec duration • 100-500 mV signal for gain calibrations• About 600 psec r.m.s. signal •Use peak for initial timing calibration


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Full detector

simulation


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CLC Simulation: event generator Simulation: event generator

ppbar processes: elastic scattering (pp pp) diffractive scattering (pp pX,pX,X1,X2) "hard core" scattering (pp X)

for luminosity only inelastic

Event generators: MBR Pythia

both have been tuned to the CDF data typical multiplicity in one ppbar primary

interaction is 5 particles per unit of . luminous region has gaussian shape in z

and t.


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CLC Simulation: CDF detector and CLCSimulation: CDF detector and CLC

CDF detector simulation based on Geant 4 simulation accounts for all secondary

particles with energy > 5MeV total number of particles detected is

considerable larger than the primary ones ~50% from IP 25% from beam pipe 25% from plug calorimeter

Gas counter simulation light yield accounts for:

the geometrical path the reflectivity (90%) threshold of the Cherenkov radiation.

-electron are below thr.


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Simulation: Momentum Simulation: Momentum ThresholdThreshold

Simulation: Momentum Simulation: Momentum ThresholdThreshold

Simulation accounts for the momentum threshold

for isobutane at 1atm threshold is for = 19 2.6 GeV pions 9.5 MeV electrons

distribution almost flat at ~ 20: 10% pressure change = 4% th change = 0.8% N particles

factor

momentum (GeV)

primaries

secondaries

all

th=20

pions ~ 2 GeV

Cherenkov p threshold

electr. ~ 8 MeV


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All particles

Particles from PV

All secondaries

Secondaries from plug

Simulation: amplitude Simulation: amplitude distributiondistribution

Simulation: amplitude Simulation: amplitude distributiondistribution

Simulated amplitude for particles from minimum bias pp interactions.

primary particles 100 p.e. peak low amplitude tail due to parallax

secondaries have low amplitude 50 p.e. threshold cuts:

84% secondaries 23% of primaries

Simulated amplitude for 5 pp interactions. primary particles

single and double particle peaks particle counting can be

performed secondaries still have low amplitude


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PMT window & electronsPMT window & electrons

Fraction of particles that hit window light yield set to 26p.e./mm window thickness = 5mm Overall effects:

peak width increased by 20% peak shift: 111 p.e. 115 p.e.

Electrons contribution mayor contribution

to secondaries electrons produced

on beampipe give large signal

all particles

hit window

electrons


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Detector

performance


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First collisionsFirst collisions

First collisions at 1.96 TeV at CDF seen by Cherenkov Luminosity Counters in October 2nd 2000

1 proton bunch vs 4 anti-proton bunches 19 ns separation between

anti-proton bunches


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Beam structure: timingBeam structure: timingT

ime

(ns)

Time (ns) Time (ns)

Collisions main bunch

Collisions satellite bunch+ losses

396 ns

Losses


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P-pbar interactions Z positionP-pbar interactions Z position

From CLC timing information determine Z position of collisions

• Was VERY useful during Tevatron commissioning:

•CLC was the only detector which could measure position of interactions during that time

•Helped a lot to AD to tune the machine


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CLC amplitude distributionCLC amplitude distribution Single Particle Peak (spp)

Higher CLC occupancy due to more material close to beam SPP clearly seen after isolation cat useful for calibration Great agreement with simulation

amplitude, spp units

amplitude, spp units

Simulation (dots)East module (blue)West module (red)


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T0 CalibrationT0 Calibration

•Calibration using p and pbar beams

Time offset

w.r.t. a reference channel

(before applying

T0 correction)

WESTWEST

EAST EAST

Time offset

w.r.t. a reference channel

(after applying

T0 correction)


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LuminosityMeasurements


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CLC Luminosity with zero counting methodLuminosity with zero counting method

1)( )1(0

0 WE eeeP

0 = probability of NO hits on both modules

E/W = probability of hits only on East/West module

Provided by Monte CarloProvided by Monte Carlo

Zero counting (empty crossing)Zero counting (empty crossing)

Measure the average of the poisson distribution by measuring the 0 bin0 bin.

An empty crossing is a BC without E–W coincidence in CLC.

In an ideal world (…acc=4 and =100%) eP )(0

…But life is tough

0 7%

E/W 12%


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Empty crossing methodEmpty crossing method

Empty crossings

Hit Counting

D0


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Real Time LuminosityReal Time Luminosity

Delivered Inst. Lum

CDF live Inst. Lum

Proton losses

Abort gap losses


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CLC Bunch by Bunch LBunch by Bunch L

Instantaneous Total

Instantaneous Total

Tevatrondelivered

CDFlive


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CLC WWllXsecs & Z Xsecs & Z ll Xsec ll Xsec

Measured with 194 pb-1


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CLC WWee yield versus luminosity yield versus luminosity

Data collected from Jun 23 to Jul 3 2004


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CLC J/J/ yield versus luminosity yield versus luminosity

Data collected from Jun 23 to Jul 3 2004


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CLC CDF vs AD LuminosityCDF vs AD Luminosity

0

20

40

60

80

100

120

0 20 40 60 80 100 120

CDF vs AD Luminosity

CDF Luminosity

AD Luminosity

LCDF

/LAD

= (1.03 ± .03) -(.0004 ± .0004)LAD

• AD calculation from Super-table (p, pbar, ’s)• Slope compares AD estimate of * with that observed at CDF

Data collected from May 17 to Jul 16 2004


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CLC CDF Luminosity vs COT currentsCDF Luminosity vs COT currents

Data collected from Jul 18 to Jul 31 2004

Removed the first hour on each store to have stable COT currents.

3%


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ConclusionsConclusions

Established all Lum measurements and accounting

Uncertainty below 5% level Used W’s for cross-check

Looks good

Implemented offline stability tests Implementing high lum algorithms

Particle counting Time clusters


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CLC PublicationsCLC Publications

“Luminosity Monitor Based on Cherenkov Counters for P Anti-P Colliders” Nucl. Instr. & Meth. A441 (366-373), 2000.

“The CDF Run II Luminosity Monitor”

Nucl. Instr. & Meth. A461 (540-544), 2001.

“The performance of the CDF Luminosity Monitor”

Submitted to Nucl. Instr. & Meth. May, 2002.


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Backup Plots:


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Test beam results


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CLC Cerenkov lightCerenkov lightCerenkov lightCerenkov light

The number of photoelectrons in a counter:

N p.e. L 2z 2

remec2 coll(E)det(E) sin2 c(E)dE

2z 2

remec2 370 cm -1 eV-1

n is usually const. over the useful range of photocathode sensitivity, therefore:

N p.e. 370L sin2c coll(E) det(E) dE

Using det(E) dE 0.27sin2 c 2(n 1)

N p.e. 200 n 1 L cm coll

n 1(no 1)P

Po

Pressure dependence:


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150 GeV

TB setupTB setup

Beam: 150 GeV pions Timing & triggering: 2 scintillating counters

upstream and downstream Drift chambers for particle position detection Alignment precision ~1mm


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TB setupTB setup

Cherenkov luminosity monitor prototipe Cone:

2 m long 50 m thick 2.0 – 4.3 cm openings 5.0 cm long light collector

Gas: 6 different choices pump: 0.1 – 2 atm

PMTs: 5 choices

19-53 cm LED:

light yield calibration


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TB setupTB setup

Electronics and data acquisition Purpose: measure amplitudes and

time differences between the counters

Feed signal to dividers. 10% for charge measurement.

Amplified 10x, delayed 250ns. sent to ADC

linearity better than 5% gated (100ns) by trigger

from scintillators 90% for time measurement.

feed linear discriminators Up scintillator starts TDC,

(50ns delayed for monitoring) Down scintillator and

Cherenkov stop TDC NIM coincidence unit to form

a trigger

Sc. Up

Sc. Down

Cher.


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CLC TB: amplitude TB: amplitude measurementmeasurement

To count photoelectron in the Cherenkov signal we need to know Np.e. /ADC.

Blue LED inside the gas volume near the entrance of the cone.

Amplitude calibration - 1 pulser at very low amplitude

ensure single photoelectron signal from PMT split:

low threshold discr. to form a trigger with the pulser

to ADC (gated with 100 ns from trigger)

Amplitude calibration – 2 Width of the amplitude spectrum

which has a gaussian form determined by statistics of photoelectron.

2p.e 1p.e.N 1


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Single p.e. Multi p.e.


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Amplitude calibration results

parameter HM R2076

HM R5800Q

HM R7057

Ph XP2978

Ph XP2020Q

, cm 19 25 29 29 53

Voltage, kV 1.8 1.6 1.6 1.4 1.7

single p.e , p.e. ~0.5 0.42 0.41 0.45 0.50

single p.e. calibration, p.e./count

~4.5 3.7 4.5 1.4 1.8

multi p.e. calibration, p.e./count

4.0 3.2 4.0 1.2 1.8


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TB: detector alignmentTB: detector alignment

Alignment provided by DC located upstream: PMT window has variable thickness, light yield in there changes with x,y. Light yield in the cone also depends on x,y. Triggering on Cherenkov signal ( PMT = 53mm)

Before alignment After alignment

PMT window light


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TB: detector alignmentTB: detector alignment

Before alignment After alignment

PMT window light

Cone light


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CLC TB: light yield from gas TB: light yield from gas and PMT windowand PMT window

Want to separate contribution of gas from the one from quartz window. Fill tube with N2 at 0.11atm and

measure light yield Fill tube with the test gas at

1.47atm, repeat measurement Keep PMT HV up for stability

Results for XP2020Q ( = 53mm) window yield increases with radius

(thickness not constant), in the center Np.e.=52 Np.e./mm=26

after correcting for pressure, isobutane has Np.e.=1225 @ 1atm, this corresponds to N0=214 p.e./cm

C4H10 – 1.47atm

N2 – 0.11atm

PMT gas only yield


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CLC TB:light yield from gas. TB:light yield from gas.

Pressure dependence isobutane

Different radiators

gas iso-C4H10 C2F6 C3F8 C4F8 SF6 N2

measured yield 100% 61% 79% 86% 58% 23%

expected yield 100% 55% 74% 87% 64% 21%

Oxigen contamination: nitrogen


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CLC TB:light from small PMTs TB:light from small PMTs

Collector efficiency tested on PMT with =53mm = 86%

Light yield in C4H10 for R5800Q

Light yield in window VS radius: measurements in 0.11atm N2.

C4H10 – 1.47atm

N2 – 0.11atm

PMT gas only yield

=53mm

=19mm

=25mm

=29mm

=29mm


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Detector assembly


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Outer layer cone + collectorOuter layer cone + collector


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CLC inner structure assembly (at UF)CLC inner structure assembly (at UF)


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CLC Quartz fiber bundles: LED Quartz fiber bundles: LED calibration systemcalibration system


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CLC The CLC modulesThe CLC modules


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Completed PMT assemblyCompleted PMT assembly


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Completed modulesCompleted modules


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LuminositySystematics


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Systematics for zero countingSystematics for zero counting

L

L

L

LL

''

)',',','(),,,( 0000 WEWE PP

Given a “baseline” set of (0, E, W)

and a new set of ('0, 'E, 'W ) both evaluated from MC

Solving

for ' we get the sys on L


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CLC Systematics: uncertainty sourcesSystematics: uncertainty sources

Inelastic p-pbar XsecInelastic p-pbar Xsec

CLC acceptance:CLC acceptance:

Geometry & generator

Beam position

CLC simulation

SPP calibrations

Acceptance stabilityAcceptance stability

Online Online offline transfer offline transfer

Beam lossesBeam losses

Statistical uncertaintyStatistical uncertainty


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CLC Systematics:Systematics: Geometry and generator Geometry and generator

Generator is Pythia (Tune A).Generator is Pythia (Tune A).Hard core + single diffractive + double diffractiveHard core + single diffractive + double diffractive

CDF simulator is Geant4CDF simulator is Geant4Modified effective thickness of beam pipeModified effective thickness of beam pipe

CLC simulation, changed the pressure of CLC simulation, changed the pressure of IsobutaneIsobutane


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CLC Geometry and generatorGeometry and generator


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CLC

Systematics on luminosity due to detector simulation and generator have been evaluated to be in total ~ 3% ~ 3% (=3(=32%)2%).

Geometry and generatorGeometry and generator


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CLC

Systematics on luminosity due to CLC simulation have been evaluated to be ~1%~1%.

CLC simulationCLC simulation

particleL

PMT

mylar cone light collector

window

cm 5~

gas

Photons propagated one by one. Photons propagated one by one.

Response depends on:Response depends on:Gas pressureGas pressureMylar reflectivityMylar reflectivityPMT efficiencyPMT efficiency


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CLC Systematics from Beam PositionSystematics from Beam Position

We split the RunII into 7 intervals with stable beam configuration in term of:

X0 ,Y0 and

X/Z, Y/Z (slopes).

We are not sensitive to Z0.


03/14/200603/14/2006

CLCSystematics from Beam PositionSystematics from Beam Position

Systematics on luminosity due to beam position is < 1%< 1%.

In every interval the beam configuration affects luminosity by less than 1%.

Taking the average over the whole RunII the effect is negligible.


03/14/200603/14/2006

CLCCLC in situ calibrationCLC in situ calibration

Store 3530 (May 25)

Init. Lum=68.4*1030

Pedestal fit

Single Particle Peak default fit

Two particle peak


03/14/200603/14/2006

CLC Systematics from SPPSystematics from SPP

ISO cut Lum dep. Fit meth.

PED syst. TOT

Systematics ON SPP 2.1% 1.2% 1.3% 1.5% 3%

See Sasha P. talk

single interaction

five interactions avg.

1 part.

1 part.

2 part.

100 p.e.secondaries

primaries

Threshold


03/14/200603/14/2006

CLC Systematics from SPPSystematics from SPPWorst case scenarioWorst case scenario

Systematics on luminosity due to SPP uncertainty is < < 1%1%.

At very low gain regime, the impact on luminosity is more significant.

Store 2606

See Sasha P. talk


03/14/200603/14/2006

CLC Contribution due to lossesContribution due to losses

We consider one store with large variation of proton losses, due to a rescraping during the store itself.

We fit the online luminosity measurement in the two regions and calculate the JUMP before and after rescraping.

Delta luminosity is an overestimation of the beam losses contribution (luminosity NEVER increases during rescraping).


03/14/200603/14/2006

CLC May 16 2004, store 3500May 16 2004, store 3500

Between 04:45 and 05:30 proton losses had been permanently above 70kHz.

Beam rescraping at 05:33

After rescraping, losses where below 20kHz.


03/14/200603/14/2006

CLC

Titolo:psfile.ps: Lum VS LossesAutore:ROOT Version 3.10/02Anteprima:L'immagine EPS non è stata salvatacon l'anteprima inclusa in essa.Commento:L'immagine EPS potrà essere stampata con una stampantePostScript e non conaltri tipi di stampante.

Contribution from beam lossesContribution from beam losses

Contributions to luminosity due to beam losses is < 1%< 1%.


03/14/200603/14/2006

CLC

Titolo:

Autore:

Anteprima:L'immagine EPS non è stata salvatacon l'anteprima inclusa in essa.Commento:L'immagine EPS potrà essere stampata con una stampantePostScript e non conaltri tipi di stampante.

Statistical uncertaintyStatistical uncertainty

For NTOT=1 ii < 4 =

Statistical uncertainty per bunch crossing is

044.08243

4:

i

i

Statistical uncertainty per single measurement (36 bunches) is

Statistical uncertainty on luminosity is negligible.negligible.

007.036

044.0

ML

L


03/14/200603/14/2006

CLC Uncertainties summaryUncertainties summary

L/L is 4.2L/L is 4.24%=4%=5.8%5.8%

Lum Range

CLC acceptance:

Geometry <3% 2x1032

Generator <2% 2x1032

Beam <1% 2x1032

CLC simulation <1%

Spp calibration <1% 2x1032

Acceptance stability 1% --Online offline transfer -- anyBackgrounds <1% --Non linearity@high L --

Statistical uncertainty -- 2x1032

Inelastic p-pbar Xsec 4% --

TOTAL <4.2%

Systematic Error


03/14/200603/14/2006

CLC

Cerenkov lightCerenkov lightCerenkov lightCerenkov light

The number of photoelectrons in a counter:

N p.e. L 2z 2

remec2 coll(E)det(E) sin2 c(E)dE

2z 2

remec2 370 cm -1 eV-1

n is usually const. over the useful range of photocathode sensitivity, therefore:

N p.e. 370L sin2c coll(E) det(E) dE

Using det(E) dE 0.27sin2 c 2(n 1)

N p.e. 200 n 1 L cm coll

n 1(no 1)P

Po

Pressure dependence:


03/14/200603/14/2006

CLC


03/14/200603/14/2006

CLC

CLC timingCLC timingCLC timingCLC timing

Precise Timing measurements: Use 1ns TDC (standard CDF) Use time stretcher circuitry

~ x 10 stretching factor

sub 100 ps resolution

CLCDiscriminator

in Transition Board Stretchers TDC


03/14/200603/14/2006

CLC

Luminosity FormulaLuminosity Formula

The major luminosity limitations are•The number of antiprotons ( )

•The proton beam brightness (Np/p)

•F<1

BNp


03/14/200603/14/2006

CLC

CLC parallaxCLC parallax

int. regionbeam


03/14/200603/14/2006

CLC

Magnetic ShieldingMagnetic Shielding

CLC

Magnetic ShieldingMagnetic Shielding

“pre-shield” optimization

Bz

(G)

Z (cm)

IndividualMu-metal shields


03/14/200603/14/2006

CLC

Cerenkov - 48 chann.Cerenkov - 48 chann.Cerenkov - 48 chann.Cerenkov - 48 chann.

Some sources of systematics: Particle multiplicity/interaction Fraction of secondaries Source of secondaries PMT window thickness Gas index of refraction


03/14/200603/14/2006

CLC

Reference ProcessesReference Processes

Process of inelastic PPbar scattering Large x-section: (CDF)

Total x-section is measured also by E710 and E811 (2.8 discrepancy with CDF)

Process: W l Complementary L measurement with different systematic

error Cross-section ~2.5nb (well known

theoretically:20%NLO,3%NNLO) Expected rate (@L=2 1032) 0.5Hz (good for integrated L) Trigger&selection efficiency ~25% (rate of ~0.1Hz after cuts)

LfR clcinelBCpp L – luminosity– # of interactions /BCinel – inelastic x-sectionclc – CLC acceptance fbc – Bunch Crossing rate

LR lWlWlW

mbinel 4.14.60

R = rate


03/14/200603/14/2006

CLC CLC effective inelastic x-CLC effective inelastic x-sectionsection

Method

CLCX-sec (mb)

2 layers

CLCX-sec (mb)

3 layers

Old simulationMBR + 3 Xo

Straight acceptance

36.9 40.5

Old simulationMBR+3 Xo

CLC/(CLC+plug)35.2 38.6

Data (CLC+plug accept from old

sim.)CLC/(CLC+plug)

35.8 38.3

New SimulationStraight

acceptance38.2 42.4

Notes: Span in x-sec is 10% So maybe error is ~ +-5 % ? Needs more time to settle and

to decide what’s “more correct” MBR inelastic is 44.4 mb ~

measured by CDF Pythia gives ~9% smaller CLC acceptance for hard-core

(@500 ADC) is ~90%. Is ~95% for lower threshold.

Need to match simulation with data as well as possible & find the right mix

• Used 500 ADC thresholds in CLC

• Used 3 GeV threshold in plug• East and West coincidence in

both• CLC+ plug acceptance in MC =

94%


03/14/200603/14/2006

CLC CLC Min. Bias Trigger

•Min. bias trigger requires at least 1 hit from East AND West CLC modules

•Loose time gate used to reduce losses contributions

•CLC min. bias trigger efficiency is studied with using orthogonal triggers to tag min. bias events

•L1_CEM0_PT4, L1_CMU0_PT8

•L1_CEM4_PT4, L1_CEM8_PT8

•L1_CMU1.5_PT1.5, L1_CMU6_PT8

• =

• =hctrig meas

tagmeastag Ntrig*tag/Ntag

/(1 - flosstag

- fnon-emptytag

)

Efficiency for tagging on hardcore events (corrected for losses and non-collision events, and assuming negligible diffractive

contributions in tagged events)


03/14/200603/14/2006

CLC CLC Min. Bias Trigger

•Min. bias trigger efficiency determined from samples of events passing Level-1 muon triggers

•Min. bias trigger efficiency as function of the sum of track Pt in the central region (-1< <1)

•Simulated trigger efficiency (req tag in CCAL > 10 GeV) is ~98%

~97.5%

~97%

0-Bias Trigger

L1_CEM0_PT4

0.9

1.0

0.5

Run #

Pt (GeV)

Documents

CLC Roberto Rossin Bologna CLC seminar, 03/14/2006 Measuring CDF’s Run II Luminosity Introduction Tevatron Luminosity measurement techniques The CLC