# Presentation: 228750

## AP2 & Debuncher Acceptance

- Keith Gollwitzer
- Director’s Review
- January 21, 2004

## The Bottom Line

- Present*****p* yield:
- 1610-6*****p*/POT
- Expected*****p* yield:
- 3610-6*****p*/POT
-  **52 ********10****10*********p*****/hr**
- Delivered to the Accumulator for stacking
- For:
- 81012 POT/pulse
- (slip stacking)
- 2.0 sec cycle time

## Goal: Lots of Pbars into Debuncher

- < 20 mm-mrad
- 20-40 mm-mrad
- > 40 mm-mrad

- Simulation of pbar transverse phase space (both planes) out of a 750 T/m lens.
- {2 entries for each pbar that only traverses Lithium part of lens}
- Collect as much as possible for Debuncher cooling systems

## Admittance Measurements

- Shottkey power (log scale)

- Shottkey power (linear scale)

- Loss monitors

- Extinction

- Extinction

- Beam Edge

- Beam Edge

- Debuncher horizontal scraper position (mm)

- _Circulating_ Admittance
- done by scraping heated
- reverse proton beam:
- Well defined edge and extinction (p/p ~ 0)

- _Operational_ Admittance
- done by scraping while
- stacking: Hard to define Beam edge & extinction
- (p/p is full mom. spread)

*Takes many stacking cycles; >0.5hr*

- Debuncher horizontal scraper position (mm)

**Old Method**

## Operational Admittance Measurements

- Make separate (few minute setup) measurements of the beam edge and extinction point
- lengthen the production cycle time to 10’s seconds
- Cooling turned OFF

- Beam Edge

- Extinction Point: Schottkey power sampled seconds after injection versus Debuncher scraper; Spectrum Analyzer goes from flat line to small step in the 0.1box of left plot above

- Extinction

- Shottkey power

- Spectrum Analyzer for
- several scraper positions

- Beam edge: Run scraper into beam between cycles starting a few seconds after injection; record loss monitors as function of scraper position

## AP2 & Debuncher Acceptance – Momentum Acceptance

- Longitudinal Schottky profile of*******p’*s filling the momentum aperture of the Debuncher.
- Bunch rotation and stochastic cooling are off.

- _NOTE_: An earlier (11/2002) measurement gives
- *p*/*p* = 4.6%

## AP2 & Debuncher Acceptance -- Parameters

**†**** **	AP2 + Debuncher admittances reported at the July 2003 review were:
- 	 Horizontal: 20 	mm-mrad, Vertical: 12  mm-mrad

|  | AP2 + Debuncher | Debuncher | TeV I Design Admittance | Goal |
| --- | --- | --- | --- | --- |
| Horizontal 
(mm-mrad) | 24 ± 3 † | 28 ± 3 * | 20  | 35  |
| Vertical 
(mm-mrad) | 18 ± 2 † | 20 ± 2 * | 20  | 35  |
| Momentum | ±2.15% | ±2.35% | ±2.00% | ±2.00% |

******* **Debuncher admittances reported at the July 2003 review were:
- 	 Horizontal: 25 	mm-mrad, Vertical: 20  mm-mrad

- Design Goal is 40  horizontal and vertical admittance everywhere within a ±2.00% momentum acceptance

## Goal: Realization of 35 mm-mrad

**Plan**:
- 	Identify & Understand Restrictions
- 		Documentation Research
- 		Optical Survey
- 		Lattice Modeling
- 		Instrumentation
- 		Beam Studies
- 	Mitigate
- 		Redesign/modify/rebuild specific elements
- 		Align/relocate specific elements
- 	Beam Based Alignment
- 		Lattice Model
- 		Instrumentation
- 		Orbit control
- 		Beam Studies

## Identify Restrictions

**Building detailed lattice models**
**	****Tech Div is performing documentation research**
**	****	****Verifying drawings with components**
**	****	****Produced tables of all apertures**
**	****Optical Survey **
**	****	****Determine alignment of AP2 & Debuncher components**
**	****	****Determine alignment of AP1, target hall & AP2**
**	****Verify lattice parameters **
**	****	****Beam studies using upgraded instrumentation **
**Models (OptiM & MAD)**
**	****Local & LBNL investigations**
**	****	****Identify restrictions and orbit control tolerances**
**	****	****Propose resolutions **

- Final Checkout

- Data 90% taken

- Crunch numbers

- Continue to feed into models

## OptiM Modeling of AP2 Acceptance

## MAD Model and Studies by LBNL

- LBNL: I. Reichel & M. Zisman

## MAD Simulations and Studies by LBNL

## Mitigation of Restrictions

**Known/Suspect**
**	****AP2 momentum collimator**
**	****	****Either scraper is moved: decrease of acceptance**
**	****	****	****Investigating whether the collimator gap can**
**	****	****	****be increase and how well matched the**
**	****	****	****collimator is matched to pipe. Need to do?**
**	****D4Q4 replacement & BPM removal/relocation**
**	****	****~No vertical tolerance for injected beam**
**	****	****	****2 large spare quad LQBs will replace quad;**
**	****	****	****same integrated field and fits into space. **
**	****	****	****Need stand work;  have existing power supply.**
**	****Motorize stands for septum & kickers **
**	****	**** ****Tolerances are small; desire to center devices**
**	****	****	****Engineering will start by looking at existing**
**	****	****	****tank motorized stands.**
**	****Injection septum (common vacuum chamber)**
**	****	**** ****Desire injected beam to be close to closed orbit**
**	****	****	****Investigating whether spare can be reworked **
**	****	****	****to minimize material at down stream end.**
**	**

- Change from build to using spares

## D4Q4 Aperture

- No tolerance for injected beam.
- Replace with large quad LQBs;
- increase vacuum chamber by 20%.
- Remove BPM from upstream area.

## Mitigation of Restrictions

**Known/Suspect continued**
**	****Band 4 cooling tanks arrays**
**	****	**** ****Array separations were designed for ~30******** mm-mrad**
**	****	****	****Investigating whether can open array gap at **
**	****	****	****the frequencies of Band 4. An alternative is**
**	****	****	****to remove half of the arrays per tank.**
**	****Move DRF2 & DRF3 to low dispersion region **
**	****	**** ****Radiation surveys show activation**
**	****	****	****-DRF3 has been moved to low dispersion.**
**	****	****	****-Looking into different schemes of where to **
**	****	****	****  ****locate DRF2 and essential electronics.**
**Other mitigations**
**	****Identification and solutions may have to wait for modeling, beam studies and/or implementation of above.**
**	****Identified that the extraction kicker’s elliptical pipe is**
**	****22******** and 36******** apertures for off momentum particles.**
**	****	****Appears that inserting a rectangular beam pipe will**
**	****	****be sufficient.**

**Recently Identified**

## Debuncher Band 4 Arrays Aperture

- Beam sizes calculated for 40 mm-mrad

- Arrays are motorized to be centered about beam

## Debuncher Extraction Kicker

**Upstream End** – Beam Profile First Turn in Debuncher– **Downstream End**
- 82% of tracked beam particles inside of ellipse.
- Rectangle of same inner dimensions accepts 91%.
- Increase horizontal dimension will accept 95%: Looking into offsetting pipe in kicker, but beam fairly small when extracting (good field region?)
- Increase vertical dimension is ~2% per mm; what does gap allow.

## AP2 & Debuncher Acceptance –– Limiting Apertures

| Device | Horizontal |  | Vertical | Schedule |
| --- | --- | --- | --- | --- |
|  |  |  |  |  |
| Band 4 H pickup | 36.8  | 37.2  | 48.7  | SD 2004 |
| Band 4 V pickup | 40.5  | 42.0  | 29.9  | SD 2004 |
| Band 4 H kicker | 36.0  | 35.5  | 48.7  | SD 2004 |
| Band 4 V kicker | 41.2  | 41.3  | 30.1  | SD 2004 |
| Deb Extr. kicker | 109.1  | 21.9  | 35.8  | SD 2006? |

**†**** **DRF3 was moved during the Fall 2003 shutdown and is no longer an aperture restriction.  Table gives pre-move admittances.

## Instrumentation Upgrades

- BPM systems
- 	Old original electronics and DAQ.
- 		Reliability, maintenance and ease of use are issues
- 	AP2 (desire <100m resolution) 53MHz
- 		Minimum is DAQ and software replacement
- 		*Still*  need to see if RF electronics are sufficient
- 	Debuncher (~50m resolution)
- 		2.5MHz Closed Orbit system (elec., DAQ & software)

- Commissioned;
- making user friendly

## Instrumentation Upgrades

- Other
- 	Re-install AP2 709 horizontal collimator
- 			Was re-installed; no beam studies yet
- 	AP2 large aperture Toroid(s)
- 		Beam intensity measurement along beam line
- 			Started discussions with vendor
- 	New
- 		Move SEMs for optimal phase advance(?)
- 		Other instrumentation as needed

## Existing AP2 Instrumentation

| System | Stacking | Rev. prot | Fwd. prot | Comment |
| --- | --- | --- | --- | --- |
| BPMs
(34) |  | Trying | Yes | Orig AM/PM Mod & DAQ
1/2 of system see kicker  |
| BLMs
(0) |  |  |  | System removed several years ago |
| SEMs
(9) | Yes | Yes | Yes | Non-optimal phase advance between SEMs |
| Intensity
(1) | Ion Chamber | Ion Chamber | Ion Chamber | Removed 3inch toroids from 6inch beam pipe |
| Collim.
(5x2) | Yes | Yes | Yes | 2 per transverse plane & 1 longitudinal sets |
| RF for BPMs | From MI | Commis.
DRF1 53MHz | From MI | DRF1: Reverse adiabatic cavities curves to “bunch” beam  |

## Existing Debuncher Instrumentation

| System | Stacking | Rev. prot | Fwd. prot | Comment |
| --- | --- | --- | --- | --- |
| BPMs
(120) |  | Yes
Yes | Yes | Orig AM/PM Mod & DAQ
Hard to maintain & use |
| BLMs
(62) | Not really | Yes | Yes |  |
| Intensity
(1) |  | DCCT | DCCT | Measures circulating current |
| Pickups
(5) | Yes | Yes | Yes | 2 are used for  stacking TBT or studies “heater” |
| Collim. | Yes | Yes | Yes | 1 scraper per plane |
| RF for BPMs |  | Re-comm. DRF3 2.5MHz | To be used | Studies RF system; new controls |

***New System commissioned***

## Orbit Control

- AP2
- 	Started with 4H+4V trims
- 	Have added 1H+3V trims
- 	Installed shunts on all dipoles of left bend
- 	Can add more trims as needed
- Debuncher
- 	Started with 13H+7V trims
- 	Started with 2 vert. plane motorized quads
- 	Have added 5 two plane motorized quads
- 	Added 10 two plane motorized quads (03)
- 	Adding 20 two plane motorized quads (04)
*No available space for trims; the ring is packed*

- Beam time needed to finish local bump commissioning

## Beam Based Alignment & More

- Basic BBA Procedure
- 	Excite a quad
- 		Most quads have shunts
- 	Measure response
- 		BPM systems for proton studies
- 		A Debuncher pickup for AP2 during stacking
- 	Correct Orbit
- 		Trims, shunts, motorized quad stands
- Other Study Programs
- 	Heat protons in Deb and watch BLMs
- 	  Paint the Debuncher aperture
- 	Prepare known emittance/momentum
- 	reverse proton beam & kick beam up AP2.

## Debuncher TBT Instrumentation

- Used for closure of AP2 injection
- QS730 changed by 16Amps
- With quad shunts, orbit through the quad centers can be  determine during stacking

- Polar Plot:
- Oscillation Amplitude (arb. Units)
- and Phase of oscillation at pickup

## Paint the Aperture

- Not Fully debugged- commissioned in 1999-2000 for Debuncher.
- For each corrector, kick until beam is extinguished: then have “painted” the aperture.

- Program has no assumptions about beam emittance and distribution, so need to extinguish beam  each corrector reach is then only about ~4
- Possible Solutions:
- 	1) Be able to prepare beam to known emittance & distribution 	    consistently before exciting any trim.
- 	2) Use combinations of trims to map out more of the aperture.
- The former needs much study time to see if possible;
- 	the latter solution shows promise on paper....

## Summary

- Beam Based Alignment will be more useful:
- 	Upgrade instrumentation
- 	Better orbit control
- 		AP2 beam line
- 			Had 13 knobs, have added 10, can add a few more
- 		Debuncher ring
- 			Had 22 knobs, have added 30, will add 40 more
- 	Our understanding of the lattices improve
- 	     and the physical apertures & tolerances
- 	Upgrade/new software applications
- Will have to mitigate limiting apertures
- 	Redesign/modify/rebuild/relocate

## Recent Beam Studies 

- Reverse proton studies
- Observation of beam signal on all AP2 BPM cables
- Commissioned Debuncher BPMs
- Commissioned bumps with new moveable quads (in progress)
- Aperture measurements
- Stacking studies
- Measure AP2 + Debuncher admittance
- 	(development of measurement techniques)
- Development of AP2 BBA using Debuncher TBT
-   bumps in AP2

## AP2 & Debuncher Acceptance – Admittance Measurement

**Improved Measurement of AP2 + Debuncher **_**Horizontal**_** Admittance**
- Figures at the right plot various measures of beam loss and intensity as a function of Debuncher horizontal scraper position.
- Measurement performed _while stacking_.
**Top scan – ****Scraper touch point**
- Bunch Rotation ON, All Cooling OFF
- Loss Monitors downstream of scraper monitored as scraper moved into beam at the end of a 30 sec stacking cycle
**Bottom scan – ****Beam extinction point**
- Bunch Rotation OFF, All Cooling OFF
- Monitor integrated power spectral density (log scale) on longitudinal schottky at the end of a 6 sec stacking cycle as scraper extinguishes the beam
- Can determine extinction point to within ±0.2 mm by observing change in schottky power above noise floor

## AP2 Beam Size & Apertures

**Horizontal** & **Vertical** **Beta Function** contribution
**Horizontal** & **Vertical** **Dispersion** contribution
- Beam envelopes in AP2 line for an admittance of 40 mm-mrad. **Aperture limitations** are shown by the lines extending from the top of the plot (**horizontal** & **vertical**).
- Synchrotron size is shown for an energy spread of 2.5%.