1. IS IT POSSIBLE TO INCREASE THE p INTENSITY FOR CNGS BY A FACTOR 2 OR 3
IS IT POSSIBLE TO INCREASE THE p INTENSITY FOR CNGS BY A FACTOR 2 OR 3 ? R. CAPPI / SL Seminar,
Introduction
Main limitations (some of)
acceptances & emittances
space-charge
double batch injection
bunch flattening
5 turn Continuous Transfer
new 5t CT
List of various schemes
Conclusion

2. speculations => studies & experiments
Introduction
The talk is a ‘simplified’ summary of the paper: CERN/PS (AE) or CERN/SL
speculations => studies & experiments
all results are PRELIMINARY and generally OPTIMISTIC
the talk will be mainly devoted to PSB-PS issues
I will not talk about collective effects ( except sp. ch.), longit. beam dynamics issues , transition crossing, etc.

3. Introduction: basic limitations
NB: The present scheme is “consistent”
i.e. LINAC, PSB, PS and SPS are all close to their limits,
i.e. there is not a single weak point
Linac2
Close to its max Ip
PSB
Space charge ~limited
Ek,max limited (1.4GeV) PS
Acceptance ~limited
5t Continous Transfer ….
SPS
Acceptance limited
Common: T & L collective effects, losses, transition, PRF , etc.
recent results

4. Acceptance & emittance issues
PS acceptance: Ax=60mm, Ay=20mm ex2 < 22mm, ey2 < 9mm
LHC ~
Ex2
Experiments
Ax limit
Ey2
Ay limit
Courtesy of R.Steerenberg

5. Present scenario & associated problems
50 MeV
PSB PS
SPS
Nt = 3.3
Limit
ex< 22
ey< 9
1.4 GeV, h<0.9
DQ x,y~ 0.13 , 0.23
ex= 25
ey= 12
Nt = 3
14 GeV/c; 5t CT ; h=0.8
NB: in all transparencies:
ex= 4sx2/bx in mm
intensities Nt are in 10^13 p
3) h is the transfer efficiency
4) yp is the p flux on target in 10^13p/s X
Limit
ex= 4.2/3 = 1.4
ey= 2.5
ex< 3
ey< 2
Nt = 4.8
G.Arduini
filling time = 1.2s
yp = 4.8/6 = G = 1

6. Space charge (at low energy in the PS)
Self field tune shift:
In the PS, to be safe :
If : T=1.4 GeV, ex = 22mm, ey = 9mm Nt < 4.8 E13 p/p
(Kb=8)
to reach it WE NEED A DOUBLE BATCH INJECTION
NB: the SPS filling time will increase by 1.2 s (or 0.6 s if PSB can pulse 2x faster* )
PS LIMIT
*) M.Benedict et al. , undergoing study

7. Double batch injection into PS: forecast
50 MeV
Limit
PSB PS
SPS
Nt = 2 x 2.4
ex< 22
ey< 9
1.4 GeV; h=1
ex= 21
ey= 9.2
DQ x,y~ 0.21 ; 0.35
Nt = 4.8 => Intensity limit
for a 1.4 GeV
14 GeV/c; old 5t CT; h=0.8
Limit X
ex= 3.4/3 = 1.13
ey= 1.4
ex< 3
ey< 2
Nt = 7.7
yp = 7.7/7.2 = G = 1.34
yp = 7.7/6.6 = 1.17 if G = 1.46

8. Recent results of high intensity double batch injection studies
Experiments
PS transformer
Beam
intensity
( E10 p/p)
1st batch
2nd batch
Time (ms)
Courtesy E. Metral

9. Comparing with LHC “ultimate beam”
DQ = 0.20, 0.26
PS transformer
Beam
intensity
( E10 p/p)
Time (ms)
Courtesy G.Metral,E. Metral

10. Can we improve space charge limits?
Increase injection energy
(e.g. with SPL)
Reduce Ip by ‘bunch flattening’ techniques:
(gain <1.5)
time

11. A new bunch flattening technique (*)
(*) C.Carli /CERN-PS AE
and EPAC2002

12. Bunch flattening in PSB: recent results
Final bunch
Initial bunch
Experiments
DQ reduction of ~28%
Courtesy C.Carli

13. 5 turn Continuous Transfer
It is the way the PS uses to fill the SPS (at 14 GeV/c)
CSPS = 11 x CPS PS PS
SPS
Present system:
+ it works
- it is lossy (~20%) x’ 2
Qx = 6.25 3 1 5 x
Extracted beam 4 .
TT2 transfo 1 2 3 4 5
ES blade
time, 2ms / div

14. Proposal for a new 5t CT (*)
The principle:
the beam is adiabatically captured into 4 islands of a 4th
order resonance properly adjusted with sextupoles and octupoles,
Initial state
Simulation results
Final state
Simulation results ES
2) then the beam is extracted similarly to the present scheme.
(*) M.Giovannozzi, R.Cappi ; Phys. Rev. Lett., V.88, i.10

15. n 5t CT: pro / con + it should be less lossy (~5%)
+ the five beamlets will match the phase space topology better =>
less betatron mismatch at injection in the SPS=> lower transv. emittance beam to SPS =>
lower losses => higher intensity
- it has to be tested experimentally

16. n5tCT: (x, x’ ) topology qx
Courtesy M.Giovannozzi
time
~ 30 ms

17. n5tCT: x-x’ measurement results
Courtesy M.E.Angoletta, A-S.Muller, M.Martini,…)

18. MAD simulations
Courtesy A-S.Muller

19. MAD simulations (suite)
Courtesy A-S.Muller

20. Expected results from: double batch+ n5tCT
50 MeV
PSB PS
SPS
Nt = 2 x 2.4
ex< 22
ey< 9
1.4 GeV, h=0.9
ex= 21
ey= 9.2
Nt = 4.8
14 GeV/c; new5t CT; h=0.9
ex= 3.4/5 = 0.68
ey= 1.4
ex< 3
ey< 2
RMKS:
10% improvement => h=0.9
=>lower transfer losses,
better matching, etc.
Nt = 8.6
filling time = 2.4s
yp = 8.6/7.2 = G = 1.49
yp = 8.6/6.6 = 1.30 if G = 1.63

21. What about the SPS ? Single bunch coll. effects: Beam loading:
8.6E13ppp => 2 E10 p/b [LHC~10 E10; e-cloud > 4 E10 (5ns?)]
Transverse impedance strongly reduced since 2002 => ~OK
Beam loading:
8.6E13ppp => 0.4 E13/ms [ LHC~0.5 E13p/ms] ~OK
better if p=26GeV/c
Transv. & long. Feedbacks
HW modifications? 20=>100 MHz?
octupoles :YES (some e x,y b.u. accepted) ~OK ?
Transition:
now 5% losses,
Etc.
K.Cornelis, T.Linnecar, E.Schaposnikova,…

22. The various schemes

23. we need a.s.a.p. clear priorities to continue at efficient speed.
Conclusion
first studies show encouraging results not only for CNGS but for LHC itself and for cleaning up the machines by improving reliability
a gain in p flux of ~1.5 seems feasible though difficult (cost ~0-2MCHF)
a gain of ~2 is maybe possible but will be more expensive (~50MCHF)
a gain of 3 will be VERY expensive ( ~300MCHF) and probably technically unrealistic
we need a.s.a.p. clear priorities to continue at efficient speed.