CNGS Target Area Beam Posit ion Monit ors OUTLI NE 1. Recap of - - PowerPoint PPT Presentation

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CNGS Target Area Beam Posit ion Monit ors OUTLI NE 1. Recap of - - PowerPoint PPT Presentation

Nov 16, 2022 228 likes •363 views

CNGS Target Area Beam Posit ion Monit ors OUTLI NE 1. Recap of Requirements & Layout 2. Monitor Candidates - Secondary Emission Monit or - Pick-up in Air 3. Recent Results - Response of Pick-ups in air t o an int ense prot on beam

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SLIDE 1

NBI2003 - Rh. Jones (CERN - AB/BDI) 1

CNGS Target Area Beam Posit ion Monit ors

OUTLI NE

  • 1. Recap of Requirements & Layout
  • 2. Monitor Candidates
  • Secondary Emission Monit or
  • Pick-up in Air

3. Recent Results

  • Response of Pick-ups in air t o an int ense

prot on beam

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SLIDE 2

NBI2003 - Rh. Jones (CERN - AB/BDI) 2

Layout of T40 Beam Diagnost ics

Target posit ion monit or f ixed t o t arget t able & aligned wrt t arget 2nd BPM at 10m Last t wo BPMs used t o provide posit ion and angle Downst ream secondary emission monit or (TBI D) used t o measure mult iplicit y, asymmet ry and secondary beam halo

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SLIDE 3

NBI2003 - Rh. Jones (CERN - AB/BDI) 3

T40 Beam Diagnost ic Requirement s

Measurement of Position and Angle of Proton Beam

  • Last 2 st andard BPMs of t he prot on beam line

⇒ used t o adj ust t raj ect ory angle ⇒ 3 t imes less accuracy required f or angle t han f or posit ion at t arget

  • Final st andard BPM of t he prot on beam line & t arget BPM

⇒ used t o provide posit ion at t he t arget ⇒ set t ing up perf ormed using f inal beam line BPM ⇒ aiming at t arget rods verif ied & t racked using t arget BPM ⇒ accuracy of measurement ±0.2mm in ±2mm cent ral region. ⇒ accuracy of measurement ±0.5mm out side ±2mm cent ral region.

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SLIDE 4

NBI2003 - Rh. Jones (CERN - AB/BDI) 4

Choice of Target St at ion Monit or

Disadvant ages Advant ages BPKG

Posit ion Pick-up

TBI U

Upst ream secondary emission monit or I nt ensit y & Posit ion Measured posit ion depends only on mechanical alignment Simple const ruct ion Radiat ion resist ant No vacuum (⇒ t est s) Lit t le ef f ect by 2ndary part icles (⇒ t est s) Posit ion only (+ int ensit y?) Cent re depends on elect ric & mechanical of f set Requires vacuum ⇒ Ti or Be windows ⇒ vacuum pump Carbon f oils ⇒ ageing not known Complicat ed & heavy

Chosen as baseline solution

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SLIDE 5

NBI2003 - Rh. Jones (CERN - AB/BDI) 5

Pick-up Choice

Elect romagnet ic St ripline Coupler Pick-up Elect rost at ic But t on Pick-up I nduct ive Pick-up

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SLIDE 6

NBI2003 - Rh. Jones (CERN - AB/BDI) 6

Test s in t he CERN-PS Boost er

Test Conditions

  • Coupler & But t on Pick-ups

inst alled in air in f ront of t he Boost er Dump

  • Beam Type
  • I nt ensit y: ~2.5E13 in 4 bunches of ~6.25E12 per bunch
  • Bunch lengt h: ~230ns
  • Bunch spacing: 572 ns
  • Energy = 1.4 GeV
  • Measurement s
  • One plane connect ed
  • Passive Hybrid used t o give Sum and Dif f erence signals
  • Dat a acquired on digit al oscilloscope
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SLIDE 7

NBI2003 - Rh. Jones (CERN - AB/BDI) 7

St ripline Coupler Test Result s

Dif f erence Signal Raw Signal f rom each elect rode (af t er 30MHz Low Pass Filt er)

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SLIDE 8

NBI2003 - Rh. Jones (CERN - AB/BDI) 8

St ripline Coupler Test Result s

  • 250
  • 200
  • 150
  • 100
  • 50

50 100 150 200

  • 30
  • 20
  • 10

10 20 30 Position (mm) Difference Signal (mV)

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SLIDE 9

NBI2003 - Rh. Jones (CERN - AB/BDI) 9

But t on Pick-up Test Result s

Expect ed Sum signal

  • 0.1
  • 0.05

0.05 0.1 0.15 0.2

  • 1.00E-07

0.00E+00 1.00E-07 2.00E-07 3.00E-07 4.00E-07 Time (s) Voltage (V)

Sum Delta

Expected Response Dif f erent iat ed Pulse

~40mV

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SLIDE 10

NBI2003 - Rh. Jones (CERN - AB/BDI) 10

But t on Pick-up Test Result s

  • 0.1
  • 0.05

0.05 0.1 0.15 0.2 0.25 0.3 0.35

  • 1.00E-06

0.00E+00 1.00E-06 2.00E-06 3.00E-06 4.00E-06 Time (s) Voltage (V)

Air I onisat ion Ef f ect s

  • Signal not dif f erent iat ed
  • Signal level ~ 5-10 t imes higher
  • Consecut ive bunch signals

increase as ionised cloud “hangs about ” af t er each bunch passage

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SLIDE 11

NBI2003 - Rh. Jones (CERN - AB/BDI) 11

But t on Pick-up Test Result s

  • 0.25
  • 0.2
  • 0.15
  • 0.1
  • 0.05

0.05 0.1 0.15 0.2 0.25

  • 1.5
  • 1
  • 0.5

0.5 1 1.5 Vertical Position (mm) Delta/Sum (arb)

Button pick- up using air ionisation is a very nice position monitor!!

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SLIDE 12

NBI2003 - Rh. Jones (CERN - AB/BDI) 12

Conclusions

Button Electrode Monitor ⇒ Sensit ive t o air ionisat ion

  • Mechanism f or observed signal response st ill under invest igat ion

⇒ Posit ion measurement possible BUT:

  • Signal amplit ude will depend non-linearly on beam int ensit y
  • Signal shape will change depending on t he level of ionisat ion

Stripline Coupler Monitor ⇒ Seems less sensit ive t o air ionisat ion t han but t on ⇒ Posit ion measurement possible BUT:

  • Noisy Signal observed (seems broadband – so possibly OK)
  • Test s using 200MHz st ruct ure CNGS beam required f or f inal

verif icat ion

  • Add solenoid or HV f or clearing ionised air cloud (?)

I nductive Monitor ⇒ Test s yet t o be perf ormed