# Presentation: 536311

## Antiproton Acceptance

**Two Projects:**
- High Gradient Lithium Lens
- 	Project Leader: Jim Morgan
- AP2 Beamline and Debuncher Acceptance Improvements
- 	Project Leader: Keith Gollwitzer

- Steve Werkema

- 2/5/2003

## Antiproton AcceptanceBasic Layout

- Scope of Antiproton Acceptance projects:
- Target station - downstream of target
- AP2 beamline
- Debuncher ring

- Steve Werkema

- 2/5/2003

## Antiproton AcceptanceMotivation

- Increase the number of antiprotons collected from the target by:
-  increasing the gradient of the collection lens
-  increasing the admittance of the AP2 beamline and the Debuncher

- MARS model of*p *phase space distribution at the center of the target
- *p*/*p* < 2.25%, contains only*p’*s within acceptance of Li Lens

- Steve Werkema

- 2/5/2003

**Notes:**
This figure assumes a lens gradient of 750 T/m. For a higher gradient the lens is closer to the target and there are morep’s within the acceptance of the lens.

## Antiproton AcceptanceHigh Gradient Lithium Lens - Parameters

|  | Present | Upgrade |
| --- | --- | --- |
| Gradient | 745 T/m | 1000 T/m |
| Radius | 1.0 cm | 1.0 cm |
| Lifetime | 9106 pulses | 10106 pulses |

- Steve Werkema

- 2/5/2003

**Notes:**
Configuration for 750 T/m.  For a higher gradient the lens is closer to the target.

## Antiproton AcceptanceHigh Gradient Lithium Lens - Motivation

- 10% increase in*p* yield by raising the gradient from 745 T/m to 1000 T/m
- Factor of 2.3 increase in*p* yield by raising the gradient to 1000 T/m _*and*_ doubling the AP2/Debuncher Admittance
- _Note_: The*p* yield improvement per gradient increase is greater at larger admittances

- Steve Werkema

- 2/5/2003

## Antiproton AcceptanceHigh Gradient Lithium Lens – Present Performance

***With the present design, the gradient would have to be lowered to 700 T/m to achieve a lifetime of 10,000,000 pulses.***

| Gradient (T/m) | Average Number of Pulses to Failure |
| --- | --- |
| 1000 | <500,000 |
| 900 | 1,000,000 |
| 800 | 3,000,000 |
| 745 | 9,000,000 |
| 700 | >10,000,000 |

- Steve Werkema

- 2/5/2003

**Notes:**
Very large uncertainty in these numbers – much variation in the data.

## Antiproton AcceptanceHigh Gradient Lithium Lens – Goals & Action Plan

_**Goal**_**:**	Operate a Lithium lens --
-  at a gradient of at least 1000 T/m
-  for at least 10 million pulses
_**Action**_** **_**Plan**_** **(in process for past 5 years):
- Liquid Li Lens development at BINP
- Improvement to present design
- FEA model of present design
- Autopsies of failed lenses
- New solid Li Lens design

- Steve Werkema

- 2/5/2003

**Notes:**
1000 T/m was the original TeV 1 design Li Lens gradient
All the work is focused on the second part of the goal – the 10 million pulse lifetime.
Achievement of the lifetime goal with the present design would require reducing the gradient to 700 T/m 

## Antiproton AcceptanceHigh Gradient Lithium Lens – Present Li Lens

- Steve Werkema

- 2/5/2003

**Notes:**
Lens current ramp is a 350 sec half period sine wave with a peak current of 500,000 A

## Antiproton AcceptanceHigh Gradient Lithium Lens – Status

- Liquid Lithium Lens development
- 	Project terminated in FY 2002 without producing a viable
- 	lens prototype.
- Existing Lens improvements
- FEA: Peak stresses during lens operation are well below the fatigue strength of the titanium septum
- 	 *failure initiated by another mechanism*
- Autopsies of five failed lenses:
- 4 septum fractures, 1 water leak (control)
- Preliminary analysis suggests that cracking had been initiated
- 	prior to pulsing the lens
_**Result**_: Improved quality control during fabrication of new lenses

- Steve Werkema

- 2/5/2003

**Notes:**
Improved quality control:
 Use of protective shields when welding on inner septum reduces oxidation
 More uniform acid etching of inner septum with weaker acid
 Li fill procedure revamped to reduce error in pre-load and reduce time Li is in molten state

## Antiproton AcceptanceHigh Gradient Lithium Lens – New design

**Features**:
- Diffusion bonded titanium body
- Thicker septum
- Li buffer volumes eliminated

*Prototype #1 is under construction*

- Steve Werkema

- 2/5/2003

## Antiproton AcceptanceHigh Gradient Lithium Lens – Near Future

- Complete and test new lens design prototype #1
- Lens #22 autopsy
- Longest lived lens, did not fail during pulsing
- Refine and expand FEA model
- Operate a lens constructed with improved quality control procedures
- Operate for 1 month at 745 T/m then increase to 820 T/m
- Construct 2 new lenses with a thicker septum (20% – 50% thicker)

- Steve Werkema

- 2/5/2003

## Antiproton AcceptanceAP2 & Debuncher Acceptance – Motivation

**Goal: **40  mm-mrad transverse admittance

*****p* phase space distribution exiting the lens for a gradient of 750 T/m.
- *p*/*p* < 2.25%
- Beamline optics have been adjusted to match Li lens aperture.
- Blue dots are horizontal,
- Red dots are vertical
- (i.e. 2 points per*****p*).

- Steve Werkema

- 2/5/2003

## Antiproton AcceptanceAP2 & Debuncher Acceptance – Parameters

|  | Recent Measurements | Physical Aperture | Goal |
| --- | --- | --- | --- |
| Horizontal 
(mm-mrad) | 20 ± 1.5  | 40  | 40  |
| Vertical 
( mm-mrad)
 | 12 ± 1.5  | 40  | 40  |
| Momentum | ±2.25% | ±2.25% | ±2.25% |

- Steve Werkema

- 2/5/2003

**Notes:**
Note: There are a small number of elements with a physical aperture less than 40  – e.g. some Debuncher stochastic cooling tanks.

## Antiproton AcceptanceAP2 & Debuncher Acceptance – Issues

- Identification of limiting apertures
- Correction of known limiting apertures
- Beamline element alignment
- Orbit control
- More AP2 trim dipoles
- Debuncher moveable quad stands
- Element redesign
- Instrumentation issues
- BPMs

- Steve Werkema

- 2/5/2003

## Antiproton AcceptanceAP2 & Debuncher Acceptance – Status

- The following projects are presently underway:
- AP2 and Debuncher documentation survey (TD)
- Determine physical aperture everywhere in beamline from drawings and other documentation
- AP2 line trim dipoles
- 4 NDB dipole trims have been installed in the AP2 line during the past year
- Install moveable stands on selected Debuncher quads
- Cables were pulled during the January 2003 shutdown.  No new stands have been installed.
- Beam studies
- 88 Hours of beam studies in past year (next slide)
- Debuncher BPM upgrade
-  Have completed beam testing of a single BPM electronics prototype
-  One sector of the Debuncher was instrumented during the January 2003 shutdown with upgraded BPM electronics

- Steve Werkema

- 2/5/2003

## Antiproton AcceptanceAP2 & Debuncher Acceptance – Completed Studies

- Beam studies completed within the past year
- Reverse proton studies
- Re-commission and develop various beam manipulation procedures (Debuncher, AP2, DRF3, DRF1)	(36 hr)
- _Problem_: have not yet been able to see beam on AP2 BPMs
- Debuncher BPMs (Re-commission old electronics and prototype testing of new electronics)	(8 hr)
- Aperture measurements	(4 hr)
- Stacking studies
- AP2 line orbit correction	(12 hr)
- Measure AP2 + Debuncher admittance
- 	(develop measurement techniques)	(20 hr)
- Measure AP2 + Debuncher momentum aperture	(8 hr)

- Steve Werkema

- 2/5/2003

**Notes:**
Total study time = 88 hr

## Antiproton AcceptanceAP2 & Debuncher Acceptance – The Future

- Complete documentation survey
- Complete Debuncher BPM upgrade
- Install Debuncher moveable quad stands
- Build prototype portable quad alignment device
- Element redesign
- Beam Studies
- Commission new hardware
- Develop procedures (upgrade and test software & controls)
- Correct AP2 and Debuncher orbits
- 	_Note_: much of the studies plan requires the new Debuncher BPMs and/or completed installation of the moveable quad stands.

- Steve Werkema

- 2/5/2003

## Antiproton AcceptanceConclusion

- Present*p* yield:
- 1710-6 *p*/POT
- Expected*p* yield:
- 4010-6 *p*/POT
-  **58 ********10****10*********p*****/hr**
- delivered to the Accumulator for stacking
- For:
- 81012 POT/pulse
- (slip stacking)
- 2.0 sec cycle time

- Steve Werkema

- 2/5/2003

**Notes:**
Note: this stacking rate does not include slip-stacking.