CNGS Prot on beam line: news since NBI 2002 OUTLI NE 1. Overview - - PowerPoint PPT Presentation

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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CNGS Prot on beam line: news since NBI 2002

OUTLI NE

• 1. Overview
• 2. Beam optics
• 3. Trajectory correction scheme
• 4. Beam stability
• 5. Aperture checks
• 6. Need of a collimator
• 7. Summary

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Overview

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Nominal beam paramet ers

Upgrade phase: 3.5 1013 p

Beam parameters Nominal CNGS beam Nominal energy [GeV] 400 Normalized emittance [µm] H=12 V=7 Emittance [µm] H=0. 028 V= 0. 016 Momentum spread ∆p/ p

• 0. 07 % +/ - 20%

# extractions per cycle 2 separated by 50 ms # of train per extraction 1 # of bunches per train 2100 I ntensity per extraction [1013 p]

• 2. 4

Bunch length [ns] (4σ) 2

• r. m. s. bunch length [cm]

15 Bunch spacing [ns] 5 Train length [µs]

• 10. 5

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Opt ics at Target (1)

Nominal paramet ers : • Bet a at f ocus in bot h planes : 10 m

• σx , σy at 400 GeV [mm]: 0.53 / 0.4
• σ’x, σ’y at 400 GeV [mrad]: 0.05 / 0.4

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Opt ics at Target (2)

βx[m] 2.5 10 20 30 σx[mm] 0.26 0.53 0.75 0.91 βy [m] 2.5 10 20 30 σy [mm] 0.2 0.4 0.56 0.7

• Round beams
• I ncr ease σ

Going to 30 m: feasible but reaching the power supply limit and aperture limit (swapped power supplies)

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Traj ect ory correct ion scheme (1)

AI M:

• I s t he proposed scheme suf f icient ?
• Can we save some correct ors or monit ors?
• What happens if somet hing goes wrong (w.r.t . f ault y

correct ors or monit ors)

Took int o account :

Beam line errors (quad displacement , beam posit ion monit or, dipole f ield and t ilt , ext ract ion f rom SPS)

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Traj ect ory correct ion scheme (2)

2-in-3 scheme: 2 consecut ive half cells per plane out of 3 are equipped wit h Beam Posit ion Monit ors (BPMs) and correct ors. Phase advance per cell: π/ 2 Produce π bumps which may not be visible as t he t raj ect ory is heavily under-sampled. Problem worsen when some BPMs are malf unct ioning Reading of t he posit ions in bot h planes (X, Y) f or all BPMs Add one BPM

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Traj ect ory correct ion scheme (3)

Correct or st rengt h and ef f iciency scrut inized 3000 t raj ect ory correct ions

• Max. St rengt h f or t he new dipole correct ors: 60 µrad

Two correct ors were removed f rom t he scheme Use some bending magnet s as addit ional correct ors.

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Traj ect ory correct ion scheme (4)

Traj ect ory max. (mm) RMS max X bef ore t raj ect ory. Correct ion 3.57 (3.58) 10.98 (15.02) X af t er t raj ect ory correct ion 0.65 (0.65) 2.02 (2.68) Y bef ore t raj ect ory. Correct ion 3.24 (3.20) 7.50 (8.02) Y af t er t raj ect ory correct ion 0.49 (0.62) 1.42 (2.52) Reminder: max. t raj ect ory excursion allowed: 4.3 mm The proposed correct ion scheme is suf f icient

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Apert ure checks (1)

AI M:

I nvest igat e t he apert ure of t he prot on beam line

Met hod:

• Generat e 100 000 part icles according t o Gaussian dist ribut ion t o

f ollow t he cont our of t he emit t ance ellipse

• Populat e t ails of dist ribut ion

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Apert ure checks (2)

Horizont al phase space

mm mrad mm mrad

St art of t he line At t arget 10σ 10σ 6σ 6σ

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Apert ure checks (3)

Vert ical phase space

mm mrad mm mrad

St art of t he line At t arget 10σ 10σ 6σ 6σ

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Apert ure checks (4)

Fract ion of part icles lost f or dif f erent apert ure misalignment s and moment um of f set s. 100000 part icles t racked For nominal paramet ers, no part icle losses are observed. Losses occur f or larger apert ure misalignment s or larger moment um

• f f set s

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Beam st abilit y at t he t arget (1)

AI M:

I nvest igat e t he beam spot st abilit y at t he t arget Target resist ance t o non-cent ered beam

Took int o account :

Beam line imperf ect ions (quad displacement , beam posit ion monit or, main dipole f ield and t ilt , ext ract ion, power supply precision)

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Type of error Error magnit ude Horizont al σx at t arget (mm) Magnet errors Horizont al ext ract ion angle Horizont al ext ract ion posit ion Ext ract ion angle and posit ion Magnet and ext ract ion errors As def ined 10 µrad r.m.s. 0.5 mm r.m.s. As above As above Horizont al σ’x at t arget (µrad) 0.12 mm 0.11mm 0.32 mm 0.34 mm 0.36 mm 11 µrad 5 µrad 21 µrad 21 µrad 22 µrad Nominal beam size [r.m.s.] Ef f ect ive beam size [r.m.s.] 0.53 mm 0.64 mm 53 µrad 57 µrad

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Beam st abilit y at t he t arget (3)

Horizont al plane spot size is dominat ed by ext ract ion errors Vert ical beam spot size is not increased, vert ical beam posit ion is det ermined by t raj ect ory errors.

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Overall beam st abilit y at t he t arget (4)

I nj ect ion and magnet errors 0.36 mm (horizont al σ at t arget ) Tot al BPM rms incert aint y 0.32 mm (?) Target overall precision 0.30 mm (?) Tot al: ~0.60 mm For β=10 m, nominal σbeam = 0.53 mm On t arget f irst 2 rods (5 mm diamet er) : 2.5 mm – (3σbeam + 0.6mm) = 0.31 mm On t arget f ollowing rods (4 mm diamet er) : 2.0 mm – (3σbeam + 0.6mm) = -0.19mm

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Need of a collimat or (1)

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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5.5 7 5

7mm 6 σ

3.2

7mm 9mm

3.5 4.5 3.2

10.3m +/- +/- 6 σ

3.5 4.5 5.5 5 7

14 mm diameter Collimator Horn neck 9mm

7-11 November 2003 NBI 2003 Present at ion by Malika Meddahi.

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Summary

Beam dynamics st udies conf irmed earlier preliminary st udies. Result s on t raj ect ory correct ions, apert ures st udies, beam st abilit ies, need of a collimat or t o prot ect t he horn neck. Prot on beam line “on schedule” General services: Oct ober 2004 t o J uly 2005 Equipment : August 2005 t o J anuary 2006 Cold check-out : Feb-March 2006 Test wit h beam: April 2006