# Presentation: 586891

## f

- On M. I. to TeV Injection : Bunch Lengths and transfer efficiencies. Store 2150 – 2155.

- Paul Lebrun & Nikolai Kouropatkine
- Fermilab

***January 25-27  2003***

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

## Commissioned by Mike Church and Jean Slaughter: 

-  For stores 2150, 2153, and 2155 determine the magnitude of the
-  *      longitudinal emittance blowup during MI-->Tev proton and antiproton
-  *      transfers.  Use T:SBDPWS[i]  (i= Set #) from the 36 Sets of the Inject
-  *      Protons Case for the proton Dt in the Tevatron and use I:SBD04S[40] from
-  *      the 36 Sets of the Inject Protons Case for the proton Dt in the MI.  Use
-  *       T:SBDAWS[j1(i),j2(i),j3(i),j4(i)] from the 9 Sets of the Inject
-  *       Antiprotons Case (where the j's are picked appropriately -- see MDC SDA
-  *       intensity device summary for correct mapping) for the 4 antiproton  Dt's
-  *        in the Tevatron and use I:SBD04S[14,35,56,77] from the 9 Sets of the
-  *      Inject Antiprotons Case for the 4 antiproton Dt's in the MI.  Use the
-  *      MDC equations (see note on Tev emittances for stores 2070 and 2155) to
-  *      calculate Dp/p and longitudinal emittance.  Plot Dt(MI) vs Dt(Tev),
-  *      Dp/p(MI) vs Dp/p(Tev), and L_emit(MI) vs L_emit(Tev).  Look for
-  *      correlations with intensity, injection number, etc.
-  *

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

## Code  Status  

-  Starting from OSDAPhysics Java Package.  Use the TeVSBDdata and MISBDdata classes, written by Nikolai Kouropatkine.
- Wrote a class, to be soon committed in OSDA Physics, which creates a small data sheet, from which the following plots have been made.  Such this study can be repeated on other stores “ easily”, if we keep maintaining OSDAPhysics.
- (Nikolai: I had to make a small modification in TeVSBdata: we want to compute the p/p from the width instead of sigma, let us discuss this.. It is just a 2-line change. )
- Ran the code for Proton only (see late why)
- Making plots:
- Cost of such a study: ~ 2 hours of Java,  ~ 3 hours of study/making plots, ~ 1 to 2 hours of writing things up..

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

## Bunch Intensity: FBI or SBD ?

- There are many reason to believe that the intensity returned by the SBD is more accurate than the “narrow” gate, especially for pbar.
- However, the SBD software has been recently upgrade, and  (may be?) the bunch intensity returned by this front – end is the process of recalibration. In any event, here is correlation plot.

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

## Bunch Intensity: FBI vs SBD in TeV, Protons

- TeV Bunch intensity relative calibration looks pretty good <R> = 0.99, rms is 1.5%, for store 2155.

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

## Notes on Relative Calibrations.. 

- Store 2155 is O.K., but store 2150 and 2153 were “mis-calibrated”.  Bob Flora worked on the TeV SBD software, on Jan 10 2003.  Store 2155 was taken a day later. Store 2153 ramped-up on
- Jan 10 at 3:51 A.M. So the date of this re-calibration do match the discrepancy between these 3 stores.  The note from Bob Flora in the instrument log-book says:
*The SBD intensity calibration was changed on 03/01/10 Friday at 17:30. *
*New Calibration: Physical Constants*
* **Protonic Charge = 1.602189246E-19 Coulomb *
*Wall Monitor = 1.288 Ohm *
*Attenuation Ratios *
*First Splitter = 3 *
*Second Splitter = 2 *
*Fudge Factor = 1.148 --> was changed to --> 1.047 *
*The old fudge factor still remains a mystery, but the new value was chosen to*
* **reflect Alvin's estimates of the cable's dispersive tail "leakage".** *
*The amplitude of the change (10%) does match what is shown on the previous lot*
*However, Tom meyer also placed a one line note stating that he is finished with TeV FBI work, and he will describe what he has done at a later date in the TeV log book. I lost the trail on that one. ...The procedure he followed is documented, though (BeamDocs # 410) *

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

##   Bunch Length rms (width, not !)  vs Bunch Number

- No Correlation with injection number.. The feed-forward loop making correction seems to have little effect, longitudinally at least. The relative rms of the rm widths for the TeV SBD is 2.9 %

- M.I

- TeV

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

##   Bunch Length rms, TeV vs MI 

- This time, we see a clear correlation, at least, between the bunch length measured in MI and TeV.  However, there is blow-up factor of 21%, in average, (rms of 4%) .

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

##   Bunch Length rms, vs Intensity in MI

- The sign of this correlation (almost real by statistical standard) is surprising: long bunches tend to be of smaller intensity.

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

## No strong correlation with bunch number, again.. 

- No strong correlation with bunch number, again..

**Bunch Length growth and transfer efficiencies...**

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

## Disappointing and a bit mysterious: no correlation between transfer efficiency and emittance dilution ..

**Bunch Length growth and transfer efficiency, II**

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

## Momentum Spread in TeV

- The momentum spread calculation for the Tev., at 150 has been recently revisited. (Mike Church formulas..)
- The MI Java class – possibly the SBD front-end -  still uses the “linear” bucket area formulas, valid only at small emittance. So the comparison MI-TeV  is a bit unfair.

- <dp/P> = 4.99 10-4, relative r.m.s = 1.6%

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

## Antiprotons.. 

- M.I data only ! Tevatron data is missing (D.A. errors, or 0. !)
- Strong dependency on pbar transfer number, as anticipated.
- One transfer for store 2150 went south....

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003

## Status... 

- OSDA Physics software is becoming available => improve the speed and correctness of such analysis in the future.
- The data for pbar in case “Inject Pbars” is either missing or suspicious. In addition, for store 2155 at least, the pbar FBI reported D.A. errors.
- The proton data is interesting. We unfortunately have an apparent bunch lengthening of 21% going from M.I. -> TeV.
- Is this emittance dilution real?
- 		- rms calculation: consistent truncation between SBD and MI algorithms?
- 		- If not, then, why and when this bunch broadening occurs?
- 		   May be this is expected : although TeV and M.I. r.f. bucket are matched (same area in long phase space), the different voltages lead to different bunch length for a given, conserved emittance ? Then, let us compute M.I./TeV emittance “the same way” !!!
- 		Real emittance dilution due to injection energy or r.f. phase errors (most likely explanation ?)

- Bunch length Mi vs TeV - P. Lebrun

- January  27  2003