1. (on behalf of the DAFNE team)
DAFNE Status
Catia Milardi
(on behalf of the DAFNE team)
CNS1, INFN, April 2nd 2012

2. OUTLINE Luminosity results & Background Collider uptime
technical faults
consolidation activities
Ring optics developments
Beam Dynamics

3. Maximum Peak Luminosity so far …
Same peak luminosity as in 2005, but
less bunches in collision (100)
lower currents
DANE upgrade
SIDDHARTA (2009)
DANE
KLOE (2005)
Lpeak [cm-2s-1]
4.53• (5.0•1032)
1.53•1032
L∫day [pb-1]
14.98
9.8
L∫1 hour [pb-1]
1.033
0.44
I-MAX in collision [A]
1.52
1.4
I+MAX in collision [A]
1.0
1.2
Nbunches
105
111 y
0.044
0.025

4. Best day
Saturday, Dec. 17th 2011
~ 95% uptime

5. Best hourly integrated luminosity
L∫1 hour = pb-1
L∫day = 8.62 pb-1

6. 10 bunches Luminosity 10 consecutive bunches
Beam-beam is not a limiting factor
Crab-Waist sextupoles work
This result can be improved by:
Vacuum conditioning
Scrabbing in the MRp
Optimizing multibunch and high current operations

7. Specific Luminosity (December 2011)
N1: n+x = n+y = nominal tunes
n-x = n-y =
N2: betratron coupling optimized
N3: n+x = n+y = e+ tunes lower
n-x = n-y =
N4: n+x = n+y = e+ e- tunes lower
n-x = n-y =
At low currents Ls exceeds by 3 times the best value measured during the past KLOE runs.

8. DAFNE operations
Since January 2012 DAFNE operations suffered for several problems:
Hardware faults
Cooling system
Power supplies
Control system
Non reproducibility of the beam parameters in the Main Rings
Slow drift of the beam trajectory in the Transfer Lines
Radioprotection alarm in the Control Room
Adverse meteorological conditions:
DAFNE activities stopped for 6 and half days in February
Several glitches in the electric network
Water leakage from some magnets and a hole in one MRp Wiggler

9. Electrical continuity in the IR
On mid January a sudden rise occurred in the temperature of the beam pipes inside the KLOE detector due to the leak of electrical continuity in the bellows at both ends of the section common to the two beams.
Temperature Celsius degrees
BEFORE
AFTER
Restoring electrical continuity

10. Vacuum spikes in the MRe
Spikes in the vacuum pressure are observed, close by the first injection kicker, when storing the beam after a stop.
The bellows after the feedthroughs of the injection kicker, in the electron ring, have been all replaced (Jan 2012).
Possible explanation:
Dynamic vacuum still need to be improved
Small discharge in the injection kicker

11. Main Rings optics
Relying on linear optics measurements (b1, b2, n1, n2, hx, hx, xx, xy) the Main Rings optics has been rematched in order to restore:
the required betatron function at the IP as well as at the CW sextupoles
The proper phase advance between the injection kickers
Symmetry in the short sections
As a consequence of the beam rematch:
smoother injection with higher efficiency and lower radiation level
Reduced beam blow-up with the main and the opposite beam current

12. Luminosity comparison
Before optics rematch
March 2012
After optics rematch
March 2012

13. Luminosity comparison
December 2011
After optics rematch
March 2012

14. Background comparison
Before optics rematch
March 2012
After optics rematch
March 2012

15. Background comparison
December 2011
After optics rematch
March 2012

16. Wiggler faults in the Mre
(March 25th 2012)
Three out of four wigglers installed in the e- ring got seriously damaged due to a long term water leakage not detected due to a concomitant fault in the power supply board supervising ground fault occurrence.
…. discharge between the coils and the vacuum chamber
… holes in the coils
(6 mm wide)
… calcareous concretions

17. March 29th 2012 Lpeak = 1.33 cm-2s-1 L∫1 hour = 0.324 pb-1
The Wiggler faults have been recovered in two and half days and …..
March 29th 2012
Lpeak = 1.33 cm-2s-1
L∫1 hour = pb-1

18. Feedback system upgrade
Longitudinal and transverse bunch by bunch feedback have been upgraded and used routinely
Clearing electrodes for e-cloud suppression
Clearing electrodes are operative and produce the expected effect on the positron beam paremeters in terms of:
Transvese beam size
Horizontal tune-shift
Horizontal instability growth rates

19. (1/msec)

20. Turning off the electrodes the transverse vertical beam dimension enlarges
s+y (mm)
s+x (mm)
However the power supplies of the clearing electrodes must be replaced cause their load impedance changes with the beam current

21. DAFNE running cost
A lot has been done in order to reduce and optimise the demand for electrical power
Wiggler pole shaping and current reduction (730-> 400 A)
1700 kW
n. 4 Septa magnets new coils
250 kW
n. 4 Splitter magnets removal
160 kW
Dafne RF system optimization
170 kW
Dafne cooling system optimization
280 kW
Total power demand reduction
2.560 kW

22. DAFNE and the Accelerator Division
The budget necessary for the the DAFNE operation is going to be partially restored after being cut in the last two years
Personnel is steadily decreasing:
Five units have been lost in 2011 and two already in 2012
Some people are 100% involved in activities within the Division, but different from DAFNE
The number of project in the DA is increasing and some of them are becoming very demanding in terms of man power
Recently the AD underwent a general reorganization

23. Some crucial points
Peak luminosity is now comparable with the maximum achieved at the end of the KLOE run in 2005
Luminosity at low currents letting in collision 10 bunches is quite promising
At low currents the highest Ls achieved exceeds by 3 times the best value measured during the past KLOE runs
Luminosity achieved in December is reproducible regardless the IR heating problem
Transverse as well longitudinal feedback, which have been upgraded, are routinely working

24. …… and Thank you for your attention
Maximum currents stored so far in collision are:
I- ~ 1.3 A
I+ ~ 0.9 A
Clearing electrodes are effective in keeping under control the e-cloud driven instabilities in the positron ring. An even better effect is expected after replacing the electrodes power supplies.
The uptime of the Linac subsystem, after a careful maintenance plan is now higher than 80%
DAFNE while working for the KLOE-2 experiment is also providing beam to the BTF and synchrotron radiation to the LNF beam lines
Thank you for your attention