DA  NE: status report M. Preger on behalf of the DA  NE team 22/11/2010

Outline Short recall of modifications to the collider for operation with KLOE Cryogenics history Beam commissioning without and with KLOE superconducting magnet Perspectives for the next KLOE run Initiatives to be overtaken for operation of Siddharta on IR2

Modifications to the Main Rings after Siddharta (already described at the last Committee) KLOE detector rolled in on IR1 new interaction region vacuum chamber to follow the vertical displacement of the beam trajectory due to the detector magnetic field orbit correction with new permanent magnet dipoles new additional skew quadrupoles insertion of superconducting solenoid compensators additional shielding near the Interaction Point stripline electrodes for electron cloud clearing improved feedback systems with new kickers

Modifications to the Main Rings after Siddharta (already described at the last Committee) - 2 modified wigglers with shifted poles to improve lattice linearity and beam lifetime and reduce power consumption: the wigglers will be powered at 400A instead of 550A, with ≈35% reduction on their operation cost and same field as at 550A. Moreover, end-poles are new powered in series with the main ones, leading to better reproducibility of the field modified collimators to reduce backgrounds in the detector and ring impedance old bellows removed and replaced by new ones IR2 vacuum chamber refurbished and realigned Beam dump kickers in IR2 RF low level and high power sections modified for better longitudinal stability and less power consumption

Cryogenic system At the time of the last Scientific Committee the KLOE superconducting magnet was cooled and energized up to 1000 A (2300A operation value). Installation of the new cooling lines for the four superconducting compensator solenoids was under way. The whole system of detector and compensator magnets was expected to be operational within two weeks. Unfortunately several problems occurred, which have strongly delayed the commissioning of DA  NE.

Cryogenic system history the first cool-down started on April 20th on May 13th the magnet reached 4.4 K° on June 26th the magnet was partially heated (to ≈80 K°) to install the cooling lines for the compensator solenoids on July 13th the magnet was cold again between July 27th and August 12th there were three fridge-out events (turbine low T, cooling water interruption and compressed air lack) on August 23rd new cool-down started but three days after stopped again due to maintenance of the lab electric power distribution system on August 30th cool-down resumed, but the coil temperature does not go below 15 K° and for the first time an excessive cooling of the screens is observed on September 10th it is decided to warm-up the magnet to 110 K° and clean the coooling lines

Cryogenic system history - 2 cool-down after cleaning is again not successful, and on September 24th WEKA AG and Space Cryomagnetics (ex Oxford) are contacted: an intervention on a valve of the system is suggested and the leakage repaired, but again cool-down is not successful. Steve Harrison (responsible for the Oxford cryogenic project of KLOE) arrives on October 4th and suggests to perform a series of tests at 110 K° and then warm-up the magnet at room temperature and perform additional tests. following a suggestion of WEKA staff, all valve housings of the system are rectified. An O-ring wrongly mounted is found on one of the valves, but it was so since All the lines are carefully cleaned. on October 25th cool-down starts again and on November 14th the magnet is cold again (after the fastest cool- down of his history,16 days) and energized. Two days after also the compensators are operational.

20 Apr - 1° cool down 22 Giu- Installazione Comp 17 Ago- fridge out 10 Set warm up 110 K

DAFNE commissioning To avoid loosing too much time, a solution to store the beams without the KLOE solenoid was found, where the beams do not cross at the IP The lack of focusing from the KLOE solenoid has a strong impact on the ring optics, which had to be deeply modified. A structure without KLOE, but with the compensators has also been designed Horizontal Vertical

First positron stored beam September 15th

First electron stored beam September 24th

110 mA electron beam September 27th limited by beam coupling and beam size growth due to ion trapping

First measurement of the optical functions in the electron ring

220 mA in the positron ring October 4th

First measurement of the optical functions in the positron ring

1.06 A in the positron ring October 9th START of RING CONDITIONING WITH BEAM !!

Ring conditioning with beams without KLOE solenoid 14/10/ /10/2010

Electron bunch length measurement

Electron beam chromaticity measurement

Effect of electron cloud clearing electrodes on growth rate of positron beam instability

Finally, we have KLOE solenoid and compensators ON !! November 16th

Conditioning with electrons November 18th ALL SC MAGNETS ON

Conditioning with positrons November 19th ALL SC MAGNETS ON

Optics optimization with the electron beam

Perspectives for the next KLOE run Conditioning of both rings with high current beams to improve vacuum conditions and minimize beam size growth and backgrounds in KLOE Closed orbit correction and beam functions optimization Horizontal-vertical coupling minimization (already less than 1%) Optimization of beam-beam interaction and luminosity Optimization of beam collimation with the scrapers to minimize background in KLOE also during injection To do list: Start of KLOE data taking foreseen for mid January

Second Siddharta run The Accelerator Division is studying the possibility of inserting the Siddharta experiment on the second interaction region (IR2) Operation in this configuration will be alternative to the KLOE one. However, the KLOE detector and its superconducting solenoid will not be rolled out during operation of Siddharta. Each cycle of data taking for one of the two experiments will last at least 10÷12 months A new layout with low-  insertion and Crab-waist will be realized on IR2. Due to the presence of the low-  insertion in IR1 a luminosity 30÷50% lower than that obtainable with a single low-  insertion is expected

Hardware Due to the necessity to keep KLOE in place during Siddharta operation we need: two QD0 (first quadrupole around the Interaction point common to both beams) permanent magnet quadrupoles four QF1 permanent magnet quadrupoles two new electromagnetic sextupoles for the realization of the Crab-waist configuration Most of the vacuum chamber components of the previous Siddharta interaction region can be reused The overall cost is estimated in 0.5 M€

Time scale 3 months for the technical design 6 months for the construction of the permanent magnet quadrupoles and electromagnetic sextupoles: during this first period (9 months) KLOE will be operational 1 month for the installation of new hardware 2 months for commissioning with beams after the run 1 month is needed to reinstall the present interaction region and start KLOE operation again at the maximum luminosity From the OK to the project we need: