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

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

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•1032 (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

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

Best hourly integrated luminosity L∫1 hour = 0.359 pb-1 L∫day = 8.62 pb-1

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

Specific Luminosity (December 2011) N1: n+x = 0.1100 n+y = 0.1810 nominal tunes n-x = 0.0955 n-y = 0.1615 N2: betratron coupling optimized N3: n+x = 0.1020 n+y = 0.1690 e+ tunes lower n-x = 0.096 n-y = 0.1605 N4: n+x = 0.1020 n+y = 0.1690 e+ e- tunes lower n-x = 0.094 n-y = 0.1560 At low currents Ls exceeds by 3 times the best value measured during the past KLOE runs.

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

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

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

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

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

Luminosity comparison December 2011 After optics rematch March 2012

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

Background comparison December 2011 After optics rematch March 2012

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

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 = 0.324 pb-1

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

(1/msec)

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

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

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

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

…… 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