First Pass at Identifying which Tevatron Injection Devices to use in the Closure Program

Peter Bagley

Jan. 7, 1999

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Keith Engell is working on the Tevatron Closure program and is beginning to ask about injection devices for the Tevatron. This is my pass at choosing Tevatron Injection Devices to use for Closure. I've tried to summarize the relevant twiss parameters and to present my reasons for choosing certain magnets.

Mike Church has several MAD files for the P150 line. These are based on Dave Johnson's files copied on 4/14/98 from the area (this is on the cartoon cluster)
/home/room1/dej/beamlines/MI52/revise/
The twiss parameters in Church's MAD output files seem (by eye) to be reasonably close to the graph shown as Fig. 2.4-6 in the Main Injector Technical Design Handbook. The following table is based on the MAD output file.

Corrector
Name 		betax
(in m) 		mux
(2pi) 		dmux from F17K
(2pi) 		dmux from F17K
(deg) 		xeff. with F17K betay
(in m) 		muy
(2pi) 		dmuy from Lamb
(2pi) 		dmuy from Lamb
(deg) 		yeff. with Lamb
VT709 16.5 1.838 46.2 1.795 0.336 (180-59) 5.83
HT710 51.1 1.920 1.120 43 4.89 13.0 1.964
VT711 14.1 2.279 70.4 2.044 0.087 31 4.36
HT712 36.4 2.320 0.720 (180+79) -5.93 81.6 2.064
VT713* 50.3 2.350 91.2 2.075 0.056 20 3.29
HT714** 69.2 2.363 0.677 (180+64) -7.46 68.3 2.085
V714 73.7 2.373 65.4 2.096 0.035 13 1.76
Lamb 91.1 2.400 60.6 2.131 0.000 0
F17K 77.9 3.040 0.000 0 44.8 2.726
* Between the 713 and the 714 quads, the MAD file has no correctors, but in the tunnel there are vertical correctors at this location.
** Between the Q714 and the C magnet, the MAD file has vertical correctors, but in the tunnel there is a horizontal corrector at this location.
V714 is the C magnet and has its own power supply.
The Lambertsons are vertical bends.
The F17 Kicker gives a horizontal kick.

The xeff. is the [sqrt(betax) * sin(2pi*(dmux from F17K) )]. This is a measure of its strength in a "direction" orthogonal to F17K.
The yeff. is the [sqrt(betay) * sin(2pi*(dmuy from Lamb) )].

Because the F17 Kicker is several cells from the injection point, there is a considerable phase advance between it and the injection point.

The horz and vert betas are fairly high in the last bit of the transfer line. (This region is used for the matching between the transfer line/MI optics and the Tevatron optics.) As a result there is not much phase advance between last couple of trims in the transfer line.

At 711, the horz beta gets down to about 3.4 m. This is small enough to make a horz phase advance of about 0.8*pi.

For the horizontal, we could use the F17 Kicker and the HT714 trim. Rather than HT714, we could consider using HT712. This is slightly weaker because the betax there is smaller, but it is also more nearly orthogonal to the F17 Kicker.

For the vertical, we could use the Lambertson and the VT709. VT709 is the fourth corrector from the end of the transfer line. Although this is quite a ways back, the correctors closer to the end of the transfer line are very close in phase to the Lambertsons. VT709 is about 90 degrees from VT711, so the bend from VT709 will produce a maximum vertical displacement near 711. If the vertical aperture is tight at 711, this may cause the beam to scrape. We may want to strongly consider using VT711 instead of VT709, even though VT711 is much closer to being degenerate with the Lambertsons.

I discussed this briefly with Mike Church. He prefers NOT to adjust the Lambertson or the F17 Kicker for closure but instead to use two trims per plane in the transfer line.

For the Lambertson, he is worried about hysteresis/saturation/regulation effects. Because this will be a ramped magnet, I am not as worried about hysteresis effects. Saturation effects may change the transfer constants for the Lambertsons as a function of current. However I expect that the range over which we will tune the Lambertson current will be small enough so that the bend vs. current will remain very nearly linear over our tuning range. If the Lambersons are in saturation, the transfer constants may not be the "theoretical values". However, Keith's methods of calibrating the effects of the Lambertsons using beam data should provide experimental values. I am not too worried by saturation effects. Finally the power supplies may have problems regulating for small changes in the large operating current. There may also be problems if the least significant bit in the power supply setting is too large of a change in current. If there is a shunt on the Lambertsons, this may not be a problem.

For the F17 Kicker, he suggests that we will always want to run this at the "maximum" voltage to get the most separation between the injected and the circulating beam in the Lambertsons and hence the most aperture in the Lambertsons. The changes needed for closure may be small enough so that they do not have much effect on this.

If we do NOT use the Lambertson or the F17 Kicker,

Whether we use the Lambertsons and the F17 Kicker may be determined operationally. Hopefully it should be fairly easy to change the injection devices we use in Keith's Closure program. I imagine we would start by using the HT710 and HT712 horizontal trims and the VT709 vertical trim and the V714 vertical C magnet. Later, if we are having aperture problems in the transfer line and when we have some idea of our tuning range, we may switch to using the Lambertsons, the F17 Kicker and/or other trims.

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URL: http://www-bd.fnal.gov/tevatron/injdev990107.html

Updated: 8-Jan-1999