CNGS Proton Beam Line
Instrumentation
OUTLINE
1. BPM System Update- Requirements- Acquisition system

2. BCT System Update- Requirements- Acquisition system

For other systems see NBI2002 talk by R. Jung

NBI2003 - Rh. Jones (CERN - AB/BDI)

1

CNGS Beam Position Monitoring
CNGS Beam Position Measurement Requirements
Intensity Range:
1×1012 to 3.5×1013
Original

18 Button Electrode
BPMs in TT41
60mm Aperture

340

BEAM

4 Stripline Couplers in TT40
will see both LHC & CNGS beams
110

110
short circuits

BPCKD (double)

Modified
NBI2003 - Rh. Jones (CERN - AB/BDI)

2

CNGS Beam Position Monitoring
CNGS Beam Position Measurement Acquisition SystemBPFilter

Logamp

I to VConverter

LPFilter

ABDiff.
Ampli
BP
FilterLogamp

I to VConverter

LP
FilterPosition = K * Vout

• Each signal is compressed by a logarithmic amplifier, filtered and applied

to a differential amplifier.
• The position response is: Pos ≡ [log(A/B)] = [log(A)-log(B)] ≡ (Vout) where
Vout is the voltage difference between the log-amp outputs
NBI2003 - Rh. Jones (CERN - AB/BDI)

3

CNGS Beam Position Monitoring
CNGS Beam Position Measurement Acquisition System
200MHz BP filters
Up
Directional
Coupler

PickupAtt

3 Way
SplitterLog
Amp

200MHzLog
Amp

200MHzLog
Amp

200MHz

Log
Amp

Right
DirectionalCoupler(BPK/BPG)
Down

Directional
CouplerAtt

3 Way
Splitter

Logarithmic Amplifiers
2 in parallel per electrodeVUp - Down
to improve linearity
Integrator
U+D+L+R

Left
Directional
CouplerAtt

3 Way
Splitter

200MHzLog
Amp

200MHzLog
Amp

Left - Right
Att

3 Way
Splitter

200MHzLog
Amp

200MHzLog
Amp

Auto Trigger

S
Integrator

Analog Multiplexer

200MHzADC

Manchester
encoder

1 cable transmits:• H position• V position• Intensity

HIntegrator

Sequencer

Calibrator
Logic

NBI2003 - Rh. Jones (CERN - AB/BDI)

4

CNGS Beam Position Monitoring
CNGS Beam Position Measurement Acquisition SystemWhy this choice?

⇒ low cost – as it requires only 1 coax cable per pick-up.
⇒ large dynamic range without requiring gain switching.
⇒ simple engineering⇒ autotrigger capability

Potential Problems:⇒ linearity with positiono log amp has inherent non-linearity in the % of aperture range
o hopefully improved using a compensation log amp in parallel⇒ radiation issues with digital electronics in the tunnelo Experience gained from testing LHC components
o Attempt to use radiation tolerant components
NBI2003 - Rh. Jones (CERN - AB/BDI)

5

CNGS Beam Current Monitoring
CNGS Beam Current Monitoring Requirements
Two Monitors – one at the beginning & one at the end of the line
Absolute Accuracy of 1% for the Intensity Range: 1×1012 to 3.5×1013
First BCT sees both LHC &CNGS beams•

Has to fulfill additional requirement ofLHC bunch by bunch capability(i.e. 25ns resolution)

New development for LHC Fast BCT (BFCT)••

500MHz Bandwidth→ Not required for CNGS
Low droop (~0.1%/µs)→ 1% effect for CNGS

NBI2003 - Rh. Jones (CERN - AB/BDI)

6

CNGS Beam Current Monitoring
CNGS Beam Current Measurement Acquisition System
Analogue Acquisition based on a fast
integrator chipIntegrator Output→ Designed by the Laboratoire dePhysiqueCorpusculaire,ClermontFerrand for use in the LHCb Preshower
Detector. (Large Hadron Collider beauty
experiment for precise measurements of CP
violation and rare decays)

25ns→ Uses interleaved, 20MHz integratorsand sample & hold circuitry to give BFCT Signal after 200m of Cable
40MHz data(only total sum required for CNGS)
NBI2003 - Rh. Jones (CERN - AB/BDI)

7

CNGS Beam Current Monitoring
CNGS Beam Current Measurement Calibration

Intensity (x10^10)

Fast BCT fitted with calibration winding.
Switched current source injects 128mA for 5µs
o equivalent to 2×1010 charges in 25ns
o same signal level as a CNGS train of 8.4×1012 protons
460
440
420
400
380
360
340
320300Comparison between DCCT andBFCT in the SPS
Shaded region represent ±2%01000

2000

3000
4000
Time in Cycle (ms)

NBI2003 - Rh. Jones (CERN - AB/BDI)

DCCT_SPSBFCT_SPS

5000

60008