DAΦNE Status Report

P. Raimondi

CSN1 Assisi,2004

• Summary of the FINUDA run

• Status of the Kloe run

• Performances expectations for the Kloe run

• Beam Test Facility status

• Conclusions

OUTLINEOUTLINE

DAΦNE DELIVERED LIN YEAR 2003-2004 for

FINUDA

100 bunchesI-peak = 1.1 A I+peak = 0.9 A Lpeak = 6.2 • 1031 cm-2 s-1

L?day > 3.5 pb-1

L?2003-2004 > 230 pb-1

FINUDA run results

κ= .3% Sigma_y (best)= 7.6 micronsβx = 2.5 mβy = 0.026 mεx = 0.34 mm mrd100 bunches collisions

Positron Current limit pushed up to 1.0Amps by optimizing orbit in the wigglers (with RF frequency shift) and feedbacks

Luminosity adiabatically increasing until the end of the run

Background more than acceptable although a concern at high current

FINUDA luminosity goals and limitations

Run too short to fully exploit the potential of the set- up (20% better results asintotically possible in a longer run)

IP2 Interaction Region limits:vertical and horizontal betas at the present valuesParasitic crossing effects not negligible at high current because the “high” x- beta and the small crossing angle

IP1 interaction region degrades the performances:at low current (coupling and orbit distorsions necessary to separate the beams)at high current (chromaticity and parasitic beam- beam crossing)

New FINUDA run luminosity expectations

With the present set- up:20% better results (asintotically) because we start from a consolidated situation (and much faster turn- on)

IP2 Interaction Region limits stay, possibly less background with added shielding in the detector, in the PM quads region

IP1 interaction region limit stay: possible to increase the separation by powering the Kloe solenoid and rotate the quadrupoles to compensate the coupling (beams spiralize around each other)

Seems reasonable to expect about 0.8e32 and 5pb- 1/day luminosity, together with 30- 50% background reduction

Shutdown March 26th ÷ April 15th 2004

• FINUDA rollout & new vacuum chamber installation

• BTF upgrade

• Ordinary hardware maintenance

KLOE operations restarted onApril 15th 2400

One Interaction Region left, Finuda IR and detector removed during the April end-of-run Shutdown

Beams stored and accumulated: 2 days Coupling correction: 4 weeksBeam vacuum conditioning: 4 weeks to reach acceptable levels, but still improvingHigh current set-up: still in progress

Standard Optics setup (done):

- beams stored immediately- orbit corrected at a more than satisfactory level- optic measurements all in perfect agreement with the model (betas and dispersion)- Chromaticity and second order dispersion OK- Dynamic aperature and energy acceptance doubled wrt 2002- Injection efficiency more than 90%, 2Hz injection for both beams, routinely possible to store 1Amp in 50sec)

Kloe Start-Up: Why did take so long?

Coupling Correction (done):- Started from “nominal” Kloe and Compensator Solenoidalfield and quads rotations- Coupling about 100%- First optimization “by hand” looking at the SLM: 3%-Tried unsuccessfully several analytic schemes, all had no enough solving power and/or resolution- Cap_Sigma_y stuck to about 13microns for a long time- Measured (in site) the position of the external quadrupoles and rotated properly. Rotated the internal quadrupoles by minimizing coupling on SLM (unique optimal position,resultingto more than 2degrees off from the readout): Cap_Sigma_ydown to 9 microns- Lowered Beta_y to 1.9cm and further optimized the coupling: Cap_igma_Y down to 6.2 microns (coupling < 0.3%)

Kloe Start-Up: Why did take so long?

Background (done):- Started with background about 2 order of magnitude greater than 2002 run- Scraper brought background down to about 4 times the 2002 run- Several solutions tested to further reduce the background- By optimizing orbit at the entrance of the IR (around the splitters) and the crossing angle (around 15mrad), background has been reduced to about 60% the 2002 levels- Further optimization is possible, expecially for the background caused by the injected beam- Some further reduction expected as the vacuum improves

Kloe Start-Up: Why did take so long?

High current (still in progress):- Electrons: initially limited to 60 bunches because ion trapping from vacuum still not at the desired level, slowly brougth up to the current 105 bunches- Positrons: in principle no limitations, horizontal instability limiting the current in the early phase of the Finuda run cured but still a strong limitation to increase the current above 1.2 Amps- Transverse planes need further feedback optimization for both beams

Feedback set- up is function of several machine parameters (RF voltage, tunes beta- functions etc) and have to be readjusted each time…

Kloe Start-Up: Why is taking so long?

Tune shift and specific luminosity in 2002 and 2004beams 3- 4 times smaller at the IP w.r.t. 2002 run !!

Good luminosity agreement:KloeSLM (Synchrotron Light Monitor)Lumi from low angle babha

DAΦNE DELIVERED LIN YEAR 2003-2004 for

KLOE

105 bunchesI-peak =1.6 A I+peak = 1.2 ALpeak = 1.09e32 cm-2s-1

Lday peak = 7.26 pb-1

Lmonth > 110 pb-1

L2004 > 360 pb-1

DAΦNE second

best day

Lpeak = 1.09e32Lday = 6.401pb-1

Lbest_day=7.26pb-1

DAΦNE Peak rate on a 2hrs interval

Lhour peak = 316nb-1/hr

Corresponding to a potential of 7.6pb-1 in 24hrs of continuosoperations

Delivered 7.26pb-1 on

Sunday 19-9-2004

THIS SLIDE HAS BEEN PRESENTED AT THE CSN1 SEPT-2003

• 100-110 bunches collisions operations (done with DEAR)

• 2 Amps/beam (asimptotically in 2 year)• 2e30 single bunch luminosity (at 20 mAmps, with

present working point, with a linear extrapolation of the obtained results)

• >1hr lifetimes (at 2 Amps and 2e32) (MAD tracking code predicts >3hrs)

• 10pb-1/day, 200pb-1/month, 1.0fb-1/0.5years delivered

• Goals based on extrapolations of 2002 results and the new low betas I.R.s. All other upgrades are meant just as safety margins.

Performances goals for Kloe and Finuda (what we feel we can achieve)

Machine set-up: where we stand now

• Horizontal betas very close to the optimal, tried 20% smaller value resulting in 5% loss in luminosity, higher value incompatible with 110 bunches operation

• Vertical beta very close to the optimal value, max 5% more gain possible from further squeeze, but at the cost of increased chromaticity and instability in the vertical plane

• Tunes very close to the optimal working points near to the integer (around Qx=0.10, Qy=0.17), and seem the best compromise between minimum beam- beam blow- up and several other parameters: life- times, electrons ion trapping, maximum storable positron current, injection efficiency etc.

Machine set-up: where we stand now• Specific luminosity goes down while the currents increase,

making the luminosity going up just about linearly with current. This is mainly due to the following well quantified effects:- Bunches become longer, due the the finite ring impedance, causing about a 30% loss due the hour glass effect - An additional indirect loss from longer bunches is in an increased tune- shift (or beam- beam effects) of about 30%- Beam- beam interaction enlarges the vertical emittance, thus increasing the vertical sizes by about 20%- Ion- trapping and microwave instability increase the electron vertical size by about 30%- Noise generated by the vertical feedbacks cause a reduction in luminosity by about 15%, and force a not ideal set- up for the feedbacks (reduced gain)All these effects are evaluated at about 1.3Amps/beam and scale roughly linearly with current

Machine set up: where we are going

We understand very well all the machine parametersWe have reached record small sizes at low currentWe have a very clear idea of what are the causes of the specific luminosity drop at higher current.We do not have a clear idea of why the positrons experience a strong horizontal instability above 600mAmps, not seen for electrons and not seen until 2002, it is not excluded yet that some hardware bug did pop in during the 2003 shut-down (still looking for…)All the efforts in the next few months will be aimed at reducing the beam degradation at higher currents, and at increasing the positron current

Machine set up: where we are going

Maintain nice stable and small beams is very challenging, expecially for the feedbacks system.Just for comparison with the B- Factories, Dafne stores very similar currents but:- beams about 10 times less stiff (hence more unstable) because the lower energy- perturbations last longer because much longer damping time- much harder to control the individual bunches in the 110- bunches mode because the reduced bunch spacing (about half w.r.t B- factories)

• 5% increasing the bunches up to 110 as the vacuum still improves (asintotic limit) in the next 2-3 months

• 5% from the reduction of the vertical electron size from better vacuum as well (less ion trapping)

• 15% from the reduction of the vertical size with vertical feedback upgrade (reducing the noise induced on the beam by the amplifiers ) in the next 3-4 months

• 10-20% from positron current increase with the vertical and horizontal (doubling the power) feedback upgrade

• 10% from positron current increase by optimizing the current set-up and parameters

• 5-10% from adiabatic tuning of the present set-up and small changes of the “standard machine parameters”, already very close to the optimal, in the next 3-6 months

• Present performances expect to improve between 15-30% by the end of the year and up to 40% by the end of the run

Luminosity improvements expectations for the next few months

The previous list of improvements requires about 15hrs/week of dedicated machine time, scheduled together with the KLOE team, with an impact of about 10% on the machine uptimeA possible gain of about 60% in luminosity can be attained by shortening the bunch length by changing sign to the ring momentum compactionSuccessful tests have been already made, but one week of commissioning is needed to fully evaluate the feasibility of this solutionSuch week might be attached to our scheduled “maintainance stops”

that happen every two months to minimize the impact on operations, however we have not yet decided with the KLOE team if it is worth at the moment to invest time in very invasive Machine DevelopmentIt should also pointed out that such experiment are very important in

general to improve our understanding of the physics of the accelerators and might have a strong impact on the design of future machines

MACHINE STUDIES to go further up in luminosity

Bunch lenght shortening

• The bunch length does not appear naturally in the luminosity equation, however since the machines do mostly operate in a vertical beam-beam limited regime, the luminosity is inversely proportional to the βy and the minimum value for βy is equal to the bunch length, for smaller values the hourglass effect causesa big loss in luminosity.

• Additional luminosity reduction comes from the crossing angle, that introduces synchro-betatron coupling and an additional increase of the horizontal size, since the projected beam size along the interaction region will be larger (Piwinski angle > 0). Finally the beam-beam effects in the vertical plane are enlarged by the crossing angle together with a finite bunch length. All these combined effects make the luminosity decrease faster then 1/sz.

0,5

1

1,5

2

2,5

3

3,5

0 5 10 15 20 25

alfa < 0alfa > 0

I [mA]

σ [cm]

Potential gain in luminosity of about 50-60%

Bunch Length Comparison for e- DAFNE Ring, measured on 15/6/2004

• KLOE scheduled to run until August-2005• Deliver 2fb-1 by the end of the run, THIS IS OUR MAIN GOAL and is within our reach NOW with the present rates• Reach 150pb-1/month by the end of 2004, currently around 130pb-1/month• Reach >170pb-1/month by the end of the run• Reach L>1.4e32 by the end of the run

Prospect for the run

BTF/DOWNAIRFLY

LCCAL

AGILE

NANO2

PAMELA

FLAG

SIDDHARTA

RAP

NANO

CAPIRE

LHBb

OFF

April 22, 2004

DAFNE Beam Test Facility

2003

shi

fts

Multi-purpose facility: • H.E. detector calibration and setup• Low energy calorimetry & resolution• Low energy electromagnetic interaction studies• High multiplicity efficiency• Detectors aging and efficiency• Beam diagnostics

Fast dipole 3°/ 0°

Pulsed dipole: 7°/4°/ 0°

to main rings

to BTF

to spectrometer

In 2004: MEG, APACHE, AIRFLY, CAPIRE, NANO2…

Restart of operation with user in June 2004

E measurement

Fast dipole (3°/ 0°)

Pulsed dipole: 3°/ 0°

BTF

Upgrade layout (April 2004)

To main rings

• Estimated duty cycle:ü 80% FINUDAü 70% KLOE

Conclusions

• Delivered the target integrated luminosity for FINUDA with a3 weeks delay, achieving about 75% of the goal peak performances• New Kloe run commissioning virtually completed in about 6 weeks instead of the desired 3 weeks• No standing and no foreseen problems that can seriously limit the desired goals for the run, for the short and long term:

Lpeak > 1.3e32 up to 2e32Lday > 8pb-1 up to 10pb-1

Lmonth > 150pb-1 up to 200pb-1

• BTF successfully commissioned and routinely operating in quasi- parasitic operations (about 10% impact on the KLOE integrated luminosity) with a duty cicle > 50%