MIA optics knobs and IP knobs for PEP-II optics (+ dispersion) improvement and IP matching, and its fast

iteration during MD for accommodating orbit drift

1. Virtual HER – requires 10 to 16 minutes MIA fitting if the BPM data are good.2. HER Knob 4 comparing with the Virtual HER – an optics knob that simultaneously correct beta

beat, coupling, dispersion, and –I for better dynamic aperture is robotic with about 20 minutes MIA fitting with this upgraded MIA capability.

3. IP knobs on HER - each knob, such as, By*, IP waist, IP tilt angle, requires 5 – 10 minutes MIA fitting.

4. Invasive orbit drift compensation – requires taking MIA data and then with 5 to 10 minutes MIA fitting. Therefore we can perform many iteration during MIA dialing in shift, to make sure that the wanted machine is indeed there.

5. Expectation: While no one can give a guarantee at any time with such a large accelerator components and variables such as BPMs and orbit, under normal condition, I assume a 16 hour dedicated MIA MD can make both machine a nice-looking optics and possibly bring the HER and LER best match at IP with MIA IP matching knobs. The bottle neck is whether we take good MIA data or not, not MIA fitting since with good MIA data, a fast convergence is always guaranteed.

6. * time mentioned above are only MIA fitting time. Data taking and transfer time as well human discussion time are not included.

Yiton T. Yan

Acknowledgement: Jim Turner and Gerry Yocky for preparing the dialing-in and for remarkable capability of bringing the orbit back to where it is at the time of MIA data – key to successful MIA knob dialing in and our PEP2 colleagues for their giving me ideas, suggestions, help of data taking, Chao, Seeman, Stan, William, Mike, Decker, Woodley, Uli, Dmitry, MHD, Yuri, and Yunhai , etc.

HER22NOV05 MIA fitted

optics

Dispersion is fitted without using extra variables, i.e. no corrector is used to fit the dispersion.

Comparing MIA fitting time with several LINUX PC’s at SLAC

MIA fitting

computers

MIA with 12 Greens no Dispersion (HER) no normal-quad-skews

(Clock time)

MIA with 12 Greens with Dispersion (HER) no normal-quad skews

(Clock time)

Pepoptics (no share)* 7 min 47 sec 12 min 40 secLiveoak (no share) 6 min 22 sec 10 min 9 secNoric01 (no share) 6 min 55 sec 10 min 46 secNoric-02 (share) 7 min 25 sec 11 min 10 secStream (no share) 7 min 43 sec 12 min 43 secField (no share) 11 min 38 sec 18 min 24 sec

* Pepoptics has the maximum ram and therefore is suitable (no virtual memory used) for MIA 30 greens and all normal-skews and one-turn-map fitting.

Knob 4 (right: wanted machine)

Producing a knob needs about 5 to 20 minutes after a virtual machine is done and is pretty robotic since we can use all convenient magnets and we know both the geometric and chromatic information.

Knob 4

• Magnets strength changes to be shown at end of this talk through web direct .txt file (copied to this power pointer make alignment no good).

IP beta_Y* knob use QF7, QD6, QF5, QD4 in addition to trombones and global, local skews. Shown is the case that the by* is reduced by 0.5 mm while others are kept as much the same as that before the knob as can be seen by the overlap.

IP waist_Y knob use QF7, QD6, QF5, QD4 in addition to trombones and global, local skews. Shown is the case that the waist Y is shifted by 1 mm while others are kept as much the same as that before the knob as can be seen by the overlap.

Invasive orbit Minor Drift accommodation

• Once we have the approachable wanted model obtained timely. We can assume the BPM gains and cross couplings are the same and therefore fitting the wanted model to the updated MIA data is quite fast with variable magnet not including sextupole feed-downs.

• 5 minutes. And the inverse of that should be dialed in. This can be done very fast if online model fit.

Conclusion

1. Expectation: While no one can give a guarantee at any time with such a large accelerator components and variables such as BPMs and orbit, under normal condition, I assume a 16 hour dedicated MIA MD can make both machine a nice-looking optics and possibly bring the HER and LER best match at IP with MIA IP matching knobs. The bottle neck is whether we take good MIA data or not, not MIA fitting since with good MIA data, a fast convergence is always guaranteed.

Suggestion for buying Pepoptics 2

• If we have two Pepoptics’s at the MIA MD time, we could run MIA in two Pepoptics’s, one for the HER and the other for the LER.

• If we could run HER and LER MIA fitting in a separate computer, we could come up with many iterations to make sure the optics is what the best we can have at the end of the shift(s).

• From the last page running time comparison, the new Pepoptics 2 shhuld have 50% faster speed. It is the time to upgrade computer.

• Although SLAC has other computers to use, it could be time sharing at the MD time and could not have enough ram memory. So pepoptics 2 should also have large ram memory just as Pepoptics.