Transcript Slide 1

Dafne Upgrade with
large Piwinsky angle and crab waist
P. Raimondi
Gruppo1 Nov.2006
Outline
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Dafne luminosity History
Goals for the Finuda run
Goals for the Siddarta run
Mid-Long term plans
Luminosity history
DAFNE DELIVERED L
IN YEAR 2004-5 for
KLOE
109-111 bunches
I-peak =2.05 A
I+peak = 1.39 A
Lpeak = 1.53e32 cm-2s1
Lday peak = 9.9 pb-1
Lmonth > 215 pb-1
L2004-5 > 2200 pb-1
2006-7 goals
• Finuda Run: Goal 1ft-1 by April 30, 2007
- Start Oct-02 with cold check-outs
- 1 month commissioning
- 6 months data taking
• Siddartha Run: Goal 1ft-1 by Dec 31, 2007
- Install the new IR with cross-angle/crab-waist
and Siddartha detector (2-3 months)
- start July-1st or Sept 1st
- 1 month commissioning
- 3 months data taking
• Dafne Goal: 1033 By Dec 31, 2007
LNF September 2006
Finuda Run
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Started on Oct-02
Reestablished collisions, stored >700mAmps e+/eVacuum conditioning ‘til Oct-31
Better coupling correction wrt Kloe (just 2 rotating
quads instead of 4): 10%
Better feedbacks >10% (more current and more
stable beams)
Reduced wiggler field (-5%)
Reduced run duration
0.6*10^32 0.1ft-1/month NOW
1.5*10^32 by the end of the run, 0.2ft-1/month duable
Siddarta Luminosity
• New IR needed for Siddarta around mid-2007
Very straightforward its design to overcome some of the present
limitations and test the large crossing angle scheme
No more parasitic crossing
Very small vertical beta function
Large Piwinsky angle
Crab waist
• Fast kickers installed Better injection efficiency: 50%=>100%
No background=> topping up
Higher currents => more luminosity (10%)
• Wigglers pole modified to improve acceptance
Longer lifetimes
Less backgroung
Higher integrated luminosity (10%)
• Ti Coating in the e+ wigglers chambers
Decreased e-cloud => Higher e+ current, more luminosity (20%)
High luminosity requires:
- short bunches
- small vertical emittance
- large horizontal size and emittance
to mimimize beam-beam
For a ring:
- easy to achieve small horizontal emittance and
horizontal size
- Hard to make short bunches
Crossing angle swaps X with Z, so the high
luminosity requirements are naturally met
Luminosity goes with 1/ex and is weakly dependent
by sz
x
bY
e-
e+
2Sx/q
q
2Sz*q
z
2Sz
2Sx
Crabbed waist removes bb betratron coupling
Introduced by the crossing angle
Vertical waist has to be a function of x:
Z=0 for particles at –sx (- sx/2q at low current)
Z= sx/q for particles at + sx (sx/2q at low current)
Crabbed waist realized with a sextupole in phase with the IP in
X and at p/2 in Y
Horizontal Plane
Vertical Plane
SuperB parameters
Collisions with uncompressed beams
Crossing angle = 2*25mrad
Negligible Emittance growth
Luminosity considerations
Ineffectiveness of collisions with large crossing angle is illusive!!!
Loss due to short collision zone (say l=σz/40) is fully compensated by
denser target beam (due to much smaller vertical beam size!).
lcross
Number of particles in collision zone: N 2  N 2
sz
N1  N 2  f 0
L
4psx s y
1y 
lcross  2sx / q
re N2 by
2psy (sx  sy )
1y N1f 0  s y 
E(GeV)  I(A)  1y
34
L
1   2.167 10
2reby  sx 
by (cm)
1.2 1036 cm2s 1
No dependence on crossing angle!
Universal expression: valid for both - head-on and crossing angle collisions!
I. Koop, Novosibirsk
Tune shifts
s x  sz 2 tan 2 (q / 2)  s x 2
Raimondi-Shatilov-Zobov
formulae:
(Beam Dynamics Newsletter, 37, August 2005)
x 
re N
2p s 2 tan 2 (q / 2)  s 2
z
x
re N
y 
2p s
y
Super-B:

2
sz 2 tan 2 (q / 2)  s x 2  s y
by
sz 2 tan 2 (q / 2)  s x 2  s y


sz 2 tan 2 (q / 2)  sx 2  100 m
sz tan (q / 2)  s x
sy
2

bx
x 
2
8000 !!!
One dimensional case for βy >>σx/θ.
For βy <σx/θ also, but with crabbed waist!
sx  2.67 m
2re N bx
 0.002
2 2
p sz q
re N b y
y 
 0.072
p s y sz q
I. Koop, Novosibirsk
Beam-Beam Tails at (0.057;0.097)
Ax = ( 0.0, 12 sx); Ay = (0.0, 160 sy)
Siddharta IR Luminosity Scan
Crab On --> 0.6/q
Crab Off
0.2
0.2
0.18
0.18
0.16
0.16
0.14
0.14
0.12
0.12
0.1
0.1
0.08
0.08
0.06
0.06
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0.06
0.08
0.1
0.12
0.14
0.16
Lmax = 2.97x1033 cm-2s-1
Lmax = 1.74x1033 cm-2s-1
Lmin = 2.52x1032 cm-2s-1
Lmin = 2.78x1031 cm-2s-1
0.18
0.2
K.Ohmi
K.Ohmi
“Crabbed” waist optics
Sextupole lens
+g
Tx,y
Tx,y
Anti-sextupole lens
-g
IP
Δμx=π
Δμy=π/2
Δμx=π
Δμy=π/2
Appropriate transformations from first sextupole to IP
and from IP to anti-sextupole:
0 
 u x 1 0 
 ux
Tx   1
Tx   1

1 

F
u

F
u
 x
x 
 x
x 
Fy 
Fy 
 uy
 0
Ty   1
 Ty   1


F
0

F
u
y
 y

 y
1

Tx Tx  
1

2u
F

x x
 1
Ty Ty  
1

2u
F
y y

0

1
0

1
I. Koop, Novosibirsk
Synchrotron modulation of ξy
(Qualitative picture)
ξy(z-z0)
Crossing angle
collision.Tune shift
decreases for halo
particles.
Head-on collision.
Flat beams. Tune shift
increases for halo
particles.
Head-on collision.
Round beams.
ξy=const.
z-z0
Relative displacement
from a bunch center
Conclusion: one can expect improvement for lifetime of halo-particles!
I. Koop, Novosibirsk
L [10^33]
14
200um,20mm
200um,15mm
100um,15mm
12
M. Zobov
10
8
Present achieved currents
L=1.5e32
6
4
2
I [mA]
0
0
10
20
30
40
50
With the present achieved beam parameters
(currents, emittances, bunchlenghts etc) a luminosity in
excess of 1033 is predicted.
With 2Amps/2Amps more than 2*1033 is possible
Beam-Beam limit is way above the reachable currents
sy0/sy
1
L, 10^33
(0.057,0.097,-0.01)
(0.057,0.097,+0.01)
(0.11,0.19,-0.01)
(0.11,0.19,+0.01)
3,5
(0.057,0.097,-0.01)
(0.057,0.097,+0.01)
x^(-0.37)
0,8
3
(0.11,0.19,-0.01)
(0.11,0.19,+0.01)
2,5
0,6
x^(-0.48)
2
0,4
x^(-0.56)
1,5
0,2
1
x^(-0.50)
turns
0
0
5 10
4
1 10
SC Wigglers
5
1,5 10
5
2 10
5
2,5 10
5
Wigglers off
turns
0,5
5 10
4
SC Wigglers
1 10
5
1,5 10
5
2 10
5
Wigglers off
Dafne Wigglers
Dafne Wigglers
Very weak luminosity dependence from
damping time given the very small
bb-blowup
M. Zobov
IR layout
New beam line
IP
QF1s
QD0s
M.Biagini
IR Layout
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No splitters (on both sides)
Common beam pipe in QD0
Separated beam pipes since QF1
No dispersion in sextupoles due to splitters
Needs new extremely simplified vacuum pipe
(round everywhere, apart the y-one)
Dipole fields need to be ajusted (Blong lower,
Bshort higher)  use splitters power supplies
Doublets will be PM
All the other elements (quads, sexts etc) are in
place, need just to be moved nearby
Siddarta
View of the modified IR1 region
Similar modifications will be made in the IR2,
without the low-beta insertion
In addition in IR2 the two lines will be Vertically Separate
Qf1s
QD0
Permanent SmCo quads already ordered (about 380K$ for 6 quads)
All other IR magnets and power supplies reused
Most of the Vacuum Pipes and pumps reused
New Vacuum pipes and pumps around 50K$
Parameters for
the Siddarta run
Parameters during
the Kloe run
Np=2.65*10^10
I=13mAmp*110bunches
Emix=200nm Emiy=1nm
Coupling= 0.5%
sigx=200um
betx=0.2m
sigy=2.4um
bety=6.0mm
sigz=20mm
X_angle=2*25mrad
L(110bunches,1.43A)=1033
Np=2.65*10^10
I=13mAmp*110bunches
Emix=300nm Emiy=1.5nm
Coupling= 0.5% (with no BB)
sigx=700um
betx=1.6m
sigy=15um (5um with no BB)
bety=19.0mm
sigz=25mm
X_angle=2*16mrad
L(110bunches,1.43A)=1.5*1032
y=y+0.8/q*x*y’ crabbed waist
shift
> 20 sigma_x
> 12 sigma_y full coupled
Optical functions and
dynamic apertures
IR optics
bx=0.2m
New betas
by=6.0mm
bx=1.4m
Old betas
by=19.0mm
M.Biagini
Driven mode solution
Short circuit at ports
150 W
F.Marcellini and D. Alesini
mode1
mode2
mode3
mode4
Measures to Increase Positron Current
1. New Injection Kickers
2. New Feedback Systems
3. Ti-Coating
(D. Alesini and F. Marcellini)
New Injection Kickers
New injection kickers with 5.4 ns
pulse length have been designed to
reduce the perturbation on the
stored beam during injection
VT
VT
3 bunches
50 bunches
present pulse length ~150ns
(old kickers)
t
FWHM pulse length ~5.4 ns
t
Expected benefits:
•higher maximum stored currents
•Improved stability of colliding beams during injection
•less background allowing acquisition on during injection ?
• Kickers: design completed, asked vendors for offers
test of the pulsers in progress
- one borrowed for preliminary tests (30KV max)
- one tested up to 50 KV , but out of specks for timeduration
- one more shipped (in specks)
still problems on the high-voltage feed through (found a
working solution already, but working on improvements)
A.Drago
iGp
the new feedback system
under test at SLAC,
KEK and LNF
Third generation digital bunch-by-bunch feedback system designed for
SuperB factory (collaboration SLAC-KEK-LNF)
- Features:
- extremely compact
- gain & phase digital and remote control
- possibility to manage any betatron or synchrotron tunes
- robust response to big oscillations due to injection (using FIR filter at
8/16 taps)
- real time parameter monitoring
- powerful beam diagnostics
- main DSP loop based on FPGA (Field Programmable Gate Array)
Wiggling wiggler
Motivation: Build wiggler poles symmetric with
respect to the beam orbit
Wigglers pole modifications:
• design completed
• poles should be replaced during the shutdown
Cost estimate
Kilo-Euros
PM quads
350
IR1 vacuum chambers
75
IR2 vacuum chambers
75
Kickers pulsers
250
Kickers
70
Matching chambers for kickers (and valves)
60
Vacuum pumps
30
New wigglers poles
230
Plants Mods
60
External labor
80
Contingency
100
Total
1380+VAT
Dafne 2008 and beyond
• If 1033 is achieved (or some above 5*1032) KLOE will
start a new run with an upgraded detector.
• the only significant (in money) modifications on
Dafne could be:
- Transfer lines mods to allow trickle injection
- High Energy mods for NNbar experiment:
New Dipoles
Possibly X-Band Linac in the transfer lines to allow
on energy injection
• If the luminosity does not seems satisfactory, the
only other possibility left (at the present) is the new
machine DANAE, already at an advanced project
state.
Dafne Goals Conclusions
• A new IR for Siddarta compatible with large-crossing angle
option seems feasible
• Same IR can fit in KLOE(1 or 2)
• Predicted large luminosity boost based exclusively on pure
“back of the envelope” geometric considerations, fully
supported by extensive simulations
• 10 times more luminosity for a given current leads to a 10
times better luminosity/background ratio. Additional gain
comes from the increased (about a factor 1.2) beam stay
clear in the IR
• Possible to do top-of-the-line Accelerator Physics and R&D
for future factories (e.g: SuperB)
• Simply rematching the IP betas, it will be possible to run like
with KLOE 2004-5, with even larger beam stay clear across
the doublet:
bx: 0.2m => 1.4m
by: 6.0mm => 18mm