IS%20IT%20POSSIBLE%20TO%20INCREASE%20THE%20p%20INTENSITY%20FOR%20CNGS%20BY%20A%20FACTOR%202%20OR%203%20?%20R.%20CAPPI%20/%20SL%20Seminar,%2021.03.2002

1
IS IT POSSIBLE TO INCREASE THE p INTENSITY FOR
CNGS BY A FACTOR 2 OR 3 ?R. CAPPI / SL Seminar,
21.03.2002

• 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
Introduction

• The talk is a simplified summary of the paper
  CERN/PS 2001-041 (AE) or CERN/SL 2001-032
• speculations gt 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
• Space charge limited
• 5t Continous Transfer
• .
• SPS
• Acceptance limited
• .
• Common T L collective effects, losses,
  transition, PRF , etc.

recent results
4
Acceptance emittance issues
PS acceptance Ax60mm, Ay20mm ex2 lt 22mm,
ey2 lt 9mm LHC
5 5
Ex2
Experiments
Ax limit
Ey2
Ay limit
Courtesy of R.Steerenberg
5
Present scenario associated problems
L2
50 MeV
Limit
Nt 3.3
exlt 22 eylt 9
1.4 GeV, hlt0.9
DQ x,y 0.13 , 0.23
ex 25 ey 12
Nt 3
14 GeV/c 5t CT h0.8
X

• NB in all transparencies
• ex 4sx2/bx in mm
• intensities Nt are in 1013 p
• 3) h is the transfer efficiency
• 4) yp is the p flux on target in 1013p/s

Limit
ex 4.2/3 1.4 ey 2.5
exlt 3 eylt 2
Nt 4.8
G.Arduini
filling time 1.2s yp 4.8/6 0.8 G
1
6
Space charge (at low energy in the PS)
Self field tune shift
In the PS, to be safe
If T1.4 GeV, ex 22mm, ey 9mm Nt lt
4.8 E13 p/p (Kb8) 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
L2
50 MeV
Limit
Nt 2 x 2.4
exlt 22 eylt 9
1.4 GeV h1
ex 21 ey 9.2
DQ x,y 0.21 0.35
Nt 4.8 gt Intensity limit for a PS _at_ 1.4 GeV
14 GeV/c old 5t CT h0.8
Limit
X
exlt 3 eylt 2
ex 3.4/3 1.13 ey 1.4
Nt 7.7
yp 7.7/7.2 1.07 G 1.34 yp
7.7/6.6 1.17 if PSB_at_.6s, 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 lt1.5)

time
11
A new bunch flattening technique ()
() C.Carli /CERN-PS-2001-073-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
1
3
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,

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 gt
• less betatron mismatch at injection in the
  SPSgt lower transv. emittance beam to SPS gt
• lower losses gt 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
L2
50 MeV
Nt 2 x 2.4
exlt 22 eylt 9
1.4 GeV, h0.9
ex 21 ey 9.2
Nt 4.8
14 GeV/c new5t CT h0.9
ex 3.4/5 0.68 ey 1.4
exlt 3 eylt 2
RMKS 10 improvement gt h0.9 gtlower transfer
losses, better matching, etc.
Nt 8.6
filling time 2.4s yp 8.6/7.2 1.19 G
1.49 yp 8.6/6.6 1.30 if PSB_at_.6s G 1.63
21
What about the SPS ?

• Single bunch coll. effects
• 8.6E13ppp gt 2 E10 p/b LHC10 E10 e-cloud gt 4
  E10 (5ns?)
• Transverse impedance strongly reduced since 2002
  gt OK
• Beam loading
• 8.6E13ppp gt 0.4 E13/ms LHC0.5 E13p/ms OK
  
• better if p26GeV/c
• Transv. long. Feedbacks
• HW modifications? 20gt100 MHz?
• octupoles YES (some e x,y b.u. accepted) OK ?
• Transition
• now 5 losses,
• better if p26GeV/c
• Etc.

K.Cornelis, T.Linnecar, E.Schaposnikova,
22
The various schemes

23
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.