From Narrow to Wide Band Normalizer for Orbit and Trajectory Measurements

BI day 2000

08/12/00

PIPOS Project (TT2 & TT10)(Beam performances)

G. VismaraG. Vismara

 Present situation

 Proposals

 Beam parameters

 Technical solution

 Beam measurements

 Conclusions

BI day 2000

08/12/00

Present situation

- No Bpm’s in TT2- No Bpm’s in TT2

- 7 BPM’s in TT10- 7 BPM’s in TT10

- TLPOS electronics:- TLPOS electronics:

 Is not conceived to measureheavy ions and LHC beams

 Requires gain switching

 Obsolete components

 Difficult maintenance

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Proposals

Studies & specifications

G.Arduini & M.Giovannozzi

Steering optimization requires:

6 BPM’s in TT2

14 BPM’s in TT10

Electronics in BA269 (50%) & BA1 (50%)

Reduced cost for cables & G.P. equipment's

Active electronics present in the tunnel

Inconvenience: BPCL-1006 difficult to access(on opposite side of the custom door)

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BPM layout

$J:\IMAGES\TT10_New.jpg$

BPCK replaced by BPCL

from TI12 & 18 and TT70

Electrodes

Placed on hor. & vert. axes

Aperture ± 66.5 mm

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Beam Types

Fix target protons

2000 bunches spaced by 5 ns, 1.7 ns wide

Heavy ions for Fix target

16 bunches spaced by 131 ns, 15 ns wide

LHC

single / 84 bunch spaced by 25 ns, 2.1 ns wide

Heavy ions for LHC

4 bunches spaced by 125 ns, 2.4 ns wide

Special beams

1,8,16 bunches spaced by 262 ns, 15 ns wide

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Dynamic & frequency spectrum

f0 = 22.8 MHz

f0 = 200 MHz

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Filter

Logamp

I to V

Converter

Diff.

Ampli

Position = K * Vout

Logamp

I to V

Converter

Logarithmic normalization

A spectral line is selected, compressed by a logarithmicamplifier, filtered and applied to a differential amplifier.

The position response isPos.  [log(A/B)] = [log(A)-log(B)]  (Vout)

where Vout is the voltage difference between the log-amp outputs

Filter

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New generation circuits use several cascaded limiting amplifiers, withfix gain and wide bandwidth. Full wave rms detectors are appliedamong each stage and by summing theirs output signals, a goodapproximation to a logarithmic transfer function is obtained.

Input dynamic range : >90 dB

Input noise: < 1.5 nV/Hz

Non conformance lin.:< 0.3 dB

Limiter Bandwidth:D.C. to >2 GHz

Video Bandwidth: D.C. to 30 MHz

Logarithmic amplifier description

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$J:\IMAGES\BI_day_00\Heavy-Ions-Diff-Beam.gif$

$J:\IMAGES\BI_day_00\Heavy-Ions-Single-Beam.gif$

Beam signals (Heavy Ions)

H = 500 ns/div

V = 200 mV/div

Output Level = -51.7 dBV

for 2*1010 charge/16 bunches

H = 500 ns/div

V = 20 mV/div 1.8 mm/div

Resolution= 85 m (V plane)

for 1 s integration time

H = 500 ns/div

V = 20 mV/div 1.8 mm/div

Resolution= 85 m (V plane)

for 1 s integration time

1 s

22 MHz BP filter

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$J:\IMAGES\BI_day_00\Sgl-Bunch-LHC-Cal.jpg$

$J:\IMAGES\BI_day_00\Sgl-Bunch-LHC-Cal-diff.gif$

Calibration signal (Sgl LHC bunch)

H = 200 ns/div

V = 200 mV/div

Output level = -37.8 dBV

for 1*1010 p/bunch

H = 100 ns/div

V = 10 mV/div .9 mm/div

Resolution = 45 m over100 ns integration time

22 MHz BP filter

100 ns

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$J:\IMAGES\BI_day_00\Fix-Target_Diff.gif$

$J:\IMAGES\BI_day_00\Fix-Target.gif$

Calibration signal (Fix Target)

H = .5 s/div

V = 200 mV/div

Output Level = -37.2 dBV

for .2*1010 p/b and 500 b

H = .5 s/div

V = 10 mV/div .9 mm/div

Resolution = 25 m

for 1 s integration time

Single channel (-D)

Difference (position) (U-D)

200 MHz BP filter

1 s

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Position errors & resolutions (rms)

Non-conformity to log function:

Position dependence versus intensity:

Zero for a centered beam

Up to 250 m for a 11 mm off-center beam

200 MHz channel:

Fix Target: 25 m/ 1010 p/b and > 400 bunches

LHC : 40 m/1010 p/b and 84 bunches

22 MHz channel:

LHC single: 50 m/1010 p/b

Heavy Ions (Fix Target): 50 m/1010 Charges/b

Special : ??

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Digitization & Acquisition

Log-amp signals (BW < 4 MHz) are send to theauxiliary buildings, via coaxial cables

MoposA modified version of Mopos digitizer, withintegrator and 14 bit ADC

To improve S/N ratio two integration times areimplemented (100 ns and 1 s)

Mopos Acquisition is identical to Mopos system(VME power PC & PMC MACI)

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Timing

Only 1st Log-amp in the beam line offersauto-trigger capability

Individual timing is required for each BPM’s

Fast timing ( SPS injection pre-pulses ,rev.frequency)

Extremely long and jitter free delay units

Beam and Calibration timing are different

Slow timing (GMT) to initialize elementarycycle settings

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Calibration

Remotely triggered

Single or 40 MHz LHC bunch simulation

It offers 0 db (center) and -6 dB ratio

+6dB ratio obtained by switching coax. relays

Center position can be cross calibrate withbeam, by switching electrodes (coaxial relays)

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08/12/00

Conclusions

A special effort has been done to reduce thecost as much as possible

Investment per channel still extremely low

cables and digital electronics & servicesrepresent the largest part of the budget (~78%)

Schedule: TT2 line will be put into operationcurrent 2001 and TT10 after 2001/02 shut-down

“Good luck to my successor!”“Good luck to my successor!”