lumireview280103.ppt p. denes p. 1 luminosity monitor review concept instrument tan (tas), count n...

LumiReview280103.pptP. Denes p. 1

Luminosity Monitor Review

Luminosity Monitor Review

• ConceptInstrument TAN (TAS), count n

• RequirementsImplications of the requirements on the design ofthe luminosity monitor

• New MechanicsUpdated design for inert gas ionization chamberSuggestions/Compatibility with solid state detector

• Electronics• Previous test beam results and current test beam needs

Bill Turner, who would normally be presenting much ofthis, can not be here today, so we are filling in (at timesperhaps imperfectly)


Luminosity Monitor Concept

Luminosity Monitor Concept

D1 triplet TAS TAS triplet D1

TANTAN

IP140 m140 m

nL R

• Luminosity NMIP from n shower• Crossing Angle L+R

Instrument TAN

Massimo


TAN

TAN

IP

Instrument a Copper Bar


TAN

TAN

Instrumentation Slot


Detector Constraints - I.

Detector Constraints - I.

Charged particles swept away(Gas) Detector placed after several INT (few )m ~1 n per 3 pp interactions (in the acceptance)

Offset due to ±150 µrad crossing angle

• Horizontal, vertical or 45° crossing• ~ 80 x 80 mm2 for detector• Segment (for position)

Table 3 : Geometry of the interacting beams

Xing plane Range of

half Xing angle

Baseline 2002 Option

degree degree rad

IP1 90 45 90 90 [0175]

IP2 90 [0150]

IP5 0 45 0 90 [0175]

IP8 0 [0285]

LHC Project Document No.

LHC-B-ES-0004 rev 2.0


Detector Constraints - II.

Detector Constraints - II.

• Signal collection time < 25 ns• Modest S/N performance:

Shower fluctuations (NMIP)/NMIP ~ 30%

<npp> 1

P = 1% needs N~3000 pp interactions

2

2

31

)(

PN

⎟⎠⎞⎜

⎝⎛

≥N

Nσ

Desired precisionNumber of eventsn / pp interaction


Detector Constraints - III.

Detector Constraints - III.

0

1

2

3

4

5

6

7

8

9

10

1 10 100

Signal-to-Noise Ratio

N(with noise)/N(no noise)

Given large hadronic shower fluctuations,SNR ~ 4 or 5 is sufficient

Effect of SNRon N to achieve P


Requirements

Requirements

LBNL25 Jan. 2002

40 MHz Ionization ChamberW.C. Turner

11

Requirements (Lumi mini Workshop, 16-17 Apr. 99)

• Absolute L measurement with L/ ~ 5% > 10L for L 30 cm-2sec-1

• Cross calibration with LHC experiment measurements of L( )every few months

• Sensitivity of L measurement to variations of IP position( *, *<1 ) ( *x y mm and crossing angle x’,y* ’<10μrad) less than 1%

• Dynamic range with “reasonable” acquisition times for 1% precision to cover 10 28cm-2 sec-1 to 10 34cm-2 sec-1

• Capable of use to keep machine tuned within ~ 2% of optimum L

• Bandwidth 40 MHz to resolve the luminosity of individual bunches

• Backgrounds less than 10% of the L signal and correctable

LBNL25 Jan. 2002

40 MHz Ionization ChamberW.C. Turner

11

Requirements (Lumi mini Workshop, 16-17 Apr. 99)

• Absolute L measurement with L/ ~ 5% > 10L for L 30 cm-2sec-1

• Cross calibration with LHC experiment measurements of L( )every few months

• Sensitivity of L measurement to variations of IP position( *, *<1 ) ( *x y mm and crossing angle x’,y* ’<10μrad) less than 1%

• Dynamic range with “reasonable” acquisition times for 1% precision to cover 10 28cm-2 sec-1 to 10 34cm-2 sec-1

• Capable of use to keep machine tuned within ~ 2% of optimum L

• Bandwidth 40 MHz to resolve the luminosity of individual bunches

• Backgrounds less than 10% of the L signal and correctable

Update

Update


Requirements

Requirements

Total LAbsolute L from experimentsL/L ~ 1%Reproducibility ~ 1%Integration time ~ 1s

Bunch-by-bunch

(most stringent: )

L/L ~ 1%Integration time ~ minutes

⎟⎠⎞

⎜⎝⎛−

∝2*

2

2

0

σD

eLL

And bringing beams into collision


Total Luminosity

Total Luminosity

m=0.33 INEL=80 mb SNR=5


Bunch-by-bunch Luminosity

Bunch-by-bunch Luminosity

m=0.33 INEL=80 mb SNR=5 2808 bunches


Luminosity OptimizationLuminosity

Optimization

Transverse view at IP

Beam 1

*

Dbeam-beam separation

Beam 2

d

( )⎟⎠

⎞⎜⎝

⎛ − td

ωσ

εcos

21~

2*0LL

for ,d <<*

D = d + know d, measure to get to 0.1 * L/L 0.5%


Current Design Options

Current Design Options

Ionization Chamber

Gas Solid

Active mediumRadiation Hardness

Mechanical stability

SpeedNoise (SNR)

Ar + N

medium replaceable

fixed components low mobility doable

CdTe

hardness to be shown

depends on contacting higher mobility trivial

Very high TID - up to ~250 000 MRad/10 yrs

Access as infrequently as possible


Argon Ionization Chamber

Argon Ionization Chamber

I0

= xGAP/vD

charge/hadron = Q0 x xGAP x P [Atm] x NGAP

00

2

1)( IdttIQ ∫ ==

I0 = 2 Q0vDPNGAP

= 9.7 e–/MIP/mm x 231 MIP/h x xGAP x P x NGAP

= 0.72 nA x vD [µm/ns] x P [Atm] x NGAP

V+

xGAP

NGAP=2


Electronics

Electronics

Very high radiation levels 50 Cable between detector and preamp

CD

Z0 (50 )

(Virtual) 50

If sufficient signal, 50 resistor can be real, otherwise50 resistor has to be “virtual”


Modified Ionization Chamber Design

Modified Ionization Chamber Design

Area constrained:4 quadrants A ~ 4x4 cm2

Capacitance per gapCGAP = A/xGAP

• Gap dimensions• Gap topology• Number of gaps• Gas properties

Update of previous mechanical designGoal: simplified construction higher reliability

• Consider all configurations which fit into Cu bar volume• Consider different gases / mixtures (simulation)


Optimizing the layout

Optimizing the layout

Coax cableNGAP

xGAP

“50”

IonizationCurrent

I0

T

TimeConstant

50 x CDETECTOR


Previous Approach I.Previous

Approach I.

Series-Parallel connection

xGAP

V 3V 5V

2V 4V


Previous Approach II.

Previous Approach II.

NGAP = NSER x NPAR

Effective gas volume = xGAP x NPAR

CDETECTOR = CGAP x NPAR / NSER

Parasitics - Hard to achieve CDETECTOR, complex mechanics

NGAP = 60xGAP = 0.5mmNPAR = 10, L = 5mmNSER = 6


Improved Speed Possible

Improved Speed Possible

0

10

20

30

40

50

60

80 85 90 95 100

Ar [%] in Ar+N2

v [micron/ns] at 3kV/cm 1 Atm

Previous Operating Point

simulated with MAGBOLTZ


Drift Velocity

Drift Velocity

0 500 1000 15000

1

2

3

4

Vel

ocity

(cm

/mic

rose

c)

E(V/cm-atm)

Ar+1%N2

Ar+1.5%N2

Ar+2%N2

Ar+3%N2

Simulation

Measured

Data vs. Simulation

Ar (98%) N2 (2%)Ar (97%) N2 (3%)Ar (96%) N2 (4%)


Example: Constant 6 mm Gas Volume

Current Waveform into Preamplifier

Example: Constant 6 mm Gas Volume

Current Waveform into Preamplifier

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

000E+0 25E-9 50E-9 75E-9 100E-9

Time [s]

2 gaps3 gaps4 gaps5 gaps6 gaps

Cu

rren

t [µ

A]

at

1 A

tm A

r/N

2 (

96::

4)


6x1 mm Gaps

6x1 mm Gaps

• N has to be even

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

000E+0 25E-9 50E-9 75E-9 100E-9

Time [s]

Current at 1 Atm [

A] Effectivegas length

Intrinsiccapacitance

Driftvelocity

L x v/C

5 mm6 mm

(10/6) / 0.56/1

3.2 cm/µs4.5 cm/µs

1::1

Previous versionThis version


Detector ConceptDetector Concept

• One ground “comb” milled from a solid Cu block• Four signal “combs”• Ceramic insulation/alignment pieces (machineable MACOR)

Detector mechanical design: T. Loew, D. ChengVessel mechanical design: M. HoffFabrication design: N. Salmon, A. Mei


Assembly I.

Assembly I.

Signal comb

Alignment features(explained below)


Assembly II.

Assembly II.

Ground planes

2 mm Cu / 1 mm gap (i.e. 4 mm between plates)40 mm depth < 10::1 aspect ratio - OK for machining

Solid groundseparates all4 quadrants


Assembly III.

Assembly III.

Alignment features


Assembly IV.

Assembly IV.

One ceramic face ismetallized for bias filterand connections to rad-hard coax cable

SignalHV


Available Space

Available Space

96 mm

67 mm


Quadrant DimensionsQuadrant

Dimensions

Not to scale

94

CeramicStainlessSteel

38

40

Copper

0.5

2.5

3.54.0


Absorber Bar

Absorber Bar


Detector Housing (TAN Insert)


Detector area

Services todetector

Direct connect or patch panel

Compatible withany detector


Detector HousingDetector Housing

Signal+HVConnectors

Gas

Met

al p

ress

ure

seal

DetectorVolume

DetectorVolume

Gas


Constraints - I.

Constraints - I.

Thin wall dimensiondesigned so thatvessel withstands15 Atm.


Constraints - II.

Constraints - II.

Double-insulated, high-pressureSMA feedthroughs

Rad-hard (SiO2) cable0.141 inch (3.6 mm) øsemi-rigid


Complete Insert

Complete Insert

• Insulated from TAN by 0.5 mm ceramic• Rad-hard semi-rigid coax insulated by ceramic beads from housing• Compatible with standard lifting mechanism


Detector Mounted in Vessel

Detector Mounted in Vessel


Integration

Integration


Engineering Solution in Preparation

Engineering Solution in Preparation


CdTe

CdTe


Alternate CdTe Layout

Alternate CdTe Layout

• Reconstruction with 10-disk geometry is complicated• Could be simplified by constructing quadrant detector using 2-2.5 x 2-2.5 cm2 CdTe (several sources)

3 x 3 array of2-2.5 x 2-2.5 cm2 CdTe250 µ between chips


CdTe Assembly Using Spring Contacts

CdTe Assembly Using Spring Contacts




Same idea, but morecables (and no gas lines)


Assembly

Assembly


0

10

20

30

40

50

000E+0 25E-9 50E-9

Time [s]

Current into Preamp [

A]

Current Pulse from 2 x 2 cm2 CdTe

Current Pulse from 2 x 2 cm2 CdTe

into 50, 93 pF7 ke-/MIP, 280 MIP


CdTe vs. Ar+N2

CdTe vs. Ar+N2

CdTe - radiation-induced leakage current CdTe - Leakage current ~ T2 eT

CdTe - complicated reconstruction - can be solved with different mechanics

CdTe - Faster than Ar+N2, deconvolution required

Ar+N2 - Active medium “easy to replace”

Ar+N2 - Signal smaller than CdTe (less important - have to average over many pulses due to shower fluctuations)

Franco


Simulation

Simulation

50% of signalper quadrant

6x1 mm gaps6 ATM Ar (96%) N2 (4%)4 cm/µs drift velocityI0 = 1 µA

I0


Pulse SpeedPulse Speed

A return to baseline within 25 ns is not necessary if• Noise is uncorrelated

Averaging over many samples is required in orderto smooth out shower fluctuations

• The pulse shape is linear over the dynamic rangeNot only linearity at the peak, but also invarianceof the shape with amplitude are required

In this case, deconvolution is straight-forward


Pulse for 1 pp Interaction

Pulse for 1 pp Interaction

100.0%

0.0%

0.0%

0.0%

-0.1%

-0.1%

-0.2%

-0.4%

-0.6%

-0.7%

0.0%0.0%-0.002

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0.018

0.020

000E+0 50E-9 100E-9 150E-9 200E-9 250E-9 300E-9

Time [s]

Amplitude [V]


Deconvolution - I.

Deconvolution - I.

∑∞

−∞=−=

kkiki QaV

⎥⎥⎦

⎤

⎢⎢⎣

⎡−= ∑

=−

k

jjkjkk QaV

aQ

10

1

-0.05

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

000E+0 50E-9 100E-9 150E-9 200E-9 250E-9 300E-9

Time [s]

Amplitude [V]


Deconvolution - II.

Deconvolution - II.

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

000E+0 50E-9 100E-9 150E-9 200E-9 250E-9 300E-9

Time [s]

Amplitude [V]

t V Q2E-9 0.000 0.0

27E-9 0.349 19.952E-9 0.349 19.977E-9 0.347 19.9

102E-9 0.017 1.2127E-9 0.340 19.8152E-9 -0.001 0.2177E-9 -0.006 0.0202E-9 -0.004 0.0227E-9 -0.002 0.0252E-9 -0.001 0.0277E-9 -0.001 0.0

A 1% error (linearity, mis-termination, ...) results in a 20% error on a 1 interaction pulse preceded by a 20 interaction pulse


Pulse Shape Uniformity

Pulse Shape Uniformity

A variation of pulse shape would mean that a1/a0

is not constantPerfectly Linear

20.02

1.00 0.021.450.00

5.00

10.00

15.00

20.00

25.00

-20E-9 000E+0 20E-9 40E-9 60E-9 80E-9 100E-9

Time [s]

Amplitude

t [ns] V(i) Q(i) N(i)8 1.0000 1.0000 1.00

33 20.022520.000020.0058 1.4498 0.9991 1.0083 0.0237-0.0190-0.02


Example - 5% Shape Non-Uniformity

Example - 5% Shape Non-Uniformity

0.0225

1

0.02140.0

0.2

0.4

0.6

0.8

1.0

1.2

000E+0 10E-9 20E-9 30E-9 40E-9 50E-9

Time [ns]

Amplitude

a1/a0 differs by5% in the 2 curves


5% Shape Non-Uniformity

5% Shape Non-Uniformity

20.02

1.00 0.021.430.00

5.00

10.00

15.00

20.00

25.00

-20E-9 000E+0 20E-9 40E-9 60E-9 80E-9 100E-9

Time [s]

Amplitude

t [ns] V(i) Q(i) N(i)8 1.0000 1.0000 1.00

33 20.021419.998920.0058 1.4273 0.9766 0.9883 0.0225-0.0197-0.02

Small effect since a0 is constant.(Similar to saying pulse shape is non-linear, but gain atpeak is calibrated)


90%

91%

92%

93%

94%

95%

96%

97%

98%

99%

100%

24E-9 25E-9 26E-9 27E-9 28E-9 29E-9 30E-9

Timing Error

Timing Error

Time window for 1% variation = 2 ns


DAQ

DAQ

FE ADC FPGA

Delay

LHC 40 MHz


Timing Error

Timing Error

-6%

-4%

-2%

0%

2%

4%

6%

-2 -1 0 1 2

Timing Error [ns]

Amplitude Error [%]

M=1M=5M=10M=15M=20

For a single voltage sample per bunch, some timing erroris tolerable. Timing error will, however, influence the de-convolution. Worst case: a pulse preceded by a train ofpulses M times bigger. Then, the error on the small pulse is

Massimo

Alex


Conclusions

Conclusions

Gas detector:• Much work has been done - 2 test beam campaigns(‘00, ‘01)• New mechanical design long-term reliability• Ready for engineering prototype of final design • 2 technologies (gas, CdTe) - both have promising features,

both still need some R&D

• Plan: May ‘03: 25 ns SPS test beam (gas+CdTe)• hadron irradiation of both designs

lumireview280103.ppt p. denes p. 1 luminosity monitor review concept instrument tan (tas), count n...

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