hypothesis : scenario, sps beam sharing, cngs cycle length, sps maximum intensity

Cryodet-2 14 June 07

M. Meddahi, E. Shaposhnikova 1

Analysis of the maximum potential proton flux to CNGS

M. Meddahi and E. ShaposhnikovaCERN AB-2007-013 (PAF)

1. Hypothesis : scenario, SPS beam sharing, CNGS cycle length, SPS maximum intensity

2. CNGS design values and limitations3. SPS limitations4. Estimated proton flux



1.1- Scenarios Proton flux evaluated for 2 scenarios

Investigate the limitations from the CNGS facility and SPS

2. New accelerators (SPL, PS2), “old” SPS

1. Present accelerators



• CNGS-FT mode: 85 % (80 %) of SPS beam time1 FT (16.8 s) + 3 CNGS (18 s) + MD (4.8 s) => S1 = 0.45

• LHC set-up mode: 10 % of the SPS beam timepilot (7.2 s) + 2 CNGS (12 s) => S2 = 0.625

• LHC filling mode: 5 % (10 %) of the SPS beam time=> S3 =0

SPS users: CNGS, LHC, FT and MD S = 0.85 x 0.45 + 0.1 x 0.625 = 0.445 (0.425) => S = 0.45

SPS users: CNGS and LHCS = 0.85 + 0.1 x 0.625 = 0.9125 (0.8625) => S = 0.85

FT: Fixed Target, MD: machine Development

1.2- Beam sharing (S)



• Present accelerators:cycle duration for the SPS-CNGS: 6 s

• With PS2:– Injection at energy above gamma transition: reduce losses– Injection of the PS2 beam at once: gain 1.2 s => 6 -1.2 = 4.8 s

If also FT users : requirements on PS2 of a slow extraction ~ 1.2 sDifferent possible super cycles:50 GeV + 50 GeV : (1.2 + 1.2) s + (1.2 + 1.2 + 1.2) s = 6 s26 GeV + 50 GeV : (0.6 + 0.6) s + (1.2 + 1.2 + 1.2) s = 4.8 s50 GeV + 26 GeV : (1.2 + 1.2) s + (0.6 + 1.2 + 0.6) s = 4.8 s

1.3- CNGS cycle length



1.4- Maximum intensity in the SPS

Proton flux calculation will be done for the following intensities:

SPS proton

intensity [1013]

Comments

4.8 1997 record

Nominal SPS-CNGS intensity

5.7 2004 record

7 Cycle length is increased by 1.2 s due to double batch injection from booster to PS

10 Maximum from PS2 intensity



CNGS committed to deliver 4.5x1019 pot/year for 5 years

2- CNGS design values and limitations



I nominal = 2.4 x 1013 protons per extraction

I = 3.5x1013 per extraction, I=7x1013 per cycle assumed in design phase for equipment for which instantaneous intensity is important (e.g. target)

I = 1.38x1020 pot/year assumed (unrealistic scenario) for design of equipment for which long term effects are relevant (e.g. beam dump, cooling systems)

With some exceptions -> next slide

2- CNGS design values and limitations (part 2)



Intensity limitation from the design values of the CNGS facilityEquipment Protons per

extractionProtons

per cyclePOT per year

Radiation Protection calculation and optimisation

Soil/concrete activation: 4.5 E19Residual dose for intervention: 1.38 E20Air/water activation: 7.6 E19

Target 3.5 E13from dynamic stresses and assuming increased time between 2 extractions

1.4 E14from target cooling

2 E20 from radiation damage

Horns 3.5 E13

from powering system: maximum of 2 extractions

7 E13from water cooling system

1.38 E20 from air cooling systemand mechanical fatigue lifetime (2 E7 pulses)

Shielding,Decay Tube,Hadron stop design

1.38 E20 from air/water cooling systems

Kicker system 3.5 E13from ferrite heating, with MKE equipped with shielding stripes (TBC)from powering system: maximum of 2 extractions

1 E14marginal, pending 2007 SPS beam measurements

Instrumentation 3.5 E13from dynamic range – Electronics system



To be noted:•After 5 years of nominal operation:

some equipments will have reached their design lifetime.

• Space for any more equipments: target chamber, service gallery or surface buildings -e.g. horn capacitor banks, cooling units, extraction kicker resonant charging power supplies.

• CNGS needs to run at nominal intensity for sometime to benchmark the validity of the design and the models, assess if margins exist, the reliability and performance of equipment, the beam line operation efficiency…

• Activation of the equipment and tunnels – RP calculations/ studies required. Measured values during operation can be first scaled up to the new requested intensity for first estimate.



• Maximum available voltage in the 200 MHz system: 8 MV

Example: required RF voltage for 4.8 s SPS-CNGS cycle ~ 10 MV

• Maximum available SPS RF power in one 200 MHz cavity: 700 kW

Intensity

[1013] protons

RF power per cavity

[MW]

4.8 0.75

7 1

10 1.4

3.1- Main SPS limitation: RF voltage and power

Example: RF power per cavity needed for SPS-CNGS cycle of 4.8 s



• Critical issue for CNGS beam– Induced radiation– loss of the overall limited number of protons for the experiments

• Sources: collective effects, beam sizes…

3.2- Main SPS limitation: beam losses

Relative beam loss as a function of the SPS intensity

Beam type FT 2004 CNGS intensities

Intensity at SPS extraction [1013]

2.6 4.4 5.3 7.0

Relative loss [%] 16 24 38 Must < 20



POT/year [1019] for 200 days of operation with 80% machine efficiency

SPS cycle length 6 s 4.8 s

Injection Energy 14 GeV 26 GeV

Beam sharingMax SPS intensity @ 400GeV [x1013]

0.45 0.85 0.45 0.85

Present injectors + machines’ improvement

4.8 5 9.4

5.7 5.9 11.1

Future injectors (>2016)+ SPS RF upgrade

7 9 17.1

Future injectors + new SPS RF system + CNGS new equipment design

10 12.9 24.5

4- Estimated proton flux



Acknowledgments: M. Barnes, M. Benedikt, T. Bohl, L. Bruno, L. Ducimetiere, K. Elsener, D. Forkel-Wirth, W. Herr, R. Garoby, E. Gschwendtner,T. Linnerar, E. Montesinos, A. Pardons, S. Roesler, H. Vincke.

References of the all related studies performed during the CNGS project phase can be found in CERN-AB-2007-013 (PAF).

hypothesis : scenario, sps beam sharing, cngs cycle length, sps maximum intensity

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