# Presentation: 483709

## Machine status – December 28

- Machine status - overview
- Blue ring: ramp development
- Yellow ring:  obstruction update
- Set-up and ramp-up

## Hot from the press....

## Machine status - overview

**Yellow ring**
- At operating temperature
- PS high-current tests and shut-off done yesterday
- Beam activity during owl shift tuesdayobstruction (more later)
**Blue ring**
- almost re-commissioned for physics
-     (highlights and yet-to-do’s later)
**Injectors**
- longitudinal emittance
- re-establish high intensity (Tandem source change yesterday
-                                                     Tandem, Booster and AGS tuning)

## Blue ring – set-up with beam

**Established ramp with 90%+ transmission**
- 	key issues
**transition** and early stone tuning (orbit, chromaticity)
**coupling** control at beta* squeeze
**permit** pulls: Artus re-configuring, adjusting slow loss thresholds
**Increased intensity** up to **~4e9/bunch** and **#bunches** (ramped 14, 28, 45, 55 **bunch patterns, **68 at injection**)**
**	**(tolerable) pressure rise at** bi8, bi12, bo2**

## Blue ramp

- 55 bunches – 3-4e9

- Transmission of ramps

## Blue – yet to do

**High bunch intensity** development (>4e9/bunch)
-     with interlock on low intensity bunches
**Re-bucketing** (RF prep work done)
**Dispersion** in IR8 (2m+)
**AC dipole**, optics measurements

## Operating scenarios

- Evaluate **collision** and **event** rates for possible operating scenarios:

- Number of bunches

- Bunch intensity

|  | 28 | 45 | 55 |
| --- | --- | --- | --- |
| 3e9 | 84 | 135 | 165 |
| 5e9 | 140 | 225 | 275 |
| 7e9 | 196 | 315 | 385 |

- Phobos pressure rise?

## Yellow obstruction - chronicle

- Tuesday 28 (owleve)
- Beam not circulating - ~**250 turns** survival – beam **loses energy**
**High losses** in Q3-Q4 warm section, sector 4, does not
- 	respond to initial aperture scan
**Linear energy loss**. Calculation (independently by 3 people)
- 	indicates that loss is consistent with **~20micron** worth of
-     material (SS or Cu) – rules out valves, bellows, RF fingers...
-     (valve in q3-q4 functioning is checked)
**Radiation survey** done  radiation starts from middle of SC tank
- Install **4 new BLM’s** in Q3-Q4 region
- Decide to continue diagnosis with beam to better characterize the obstacle

## Yellow obstruction – cont’

**Q3**

**Q4**

**Warm section**

**SC**

**RF systems, vacuum valves**

- Radiation survey
- New BLM’s
- Comparison with nov28 data
- Check new BLM’s, BPMs at SC
- confirm cause
- (SC kicker? Valve? Bellow?)
- fix it

- Radiation survey

## Yellow obstruction – cont’

- Wednesday 29 (owlday)
- Improve injection and **orbit** in the machine
- Resolve **configuration issues in the BLM system** that confused analysis of losses, confirm that the BLM downstream SC tank is The One
**Move beam** +10mm vertical and -10mm horizontal and find hole **circulating beam**
**Aperture ~few mm**, not enough for operating
- More work (move SC tank, jaws, etc), no sizeable improvement
**OPEN VACUUM AT SC TANK (11am today)**
**	******** ****find aluminum **

## Fixing scenarios

- Piece of aluminum foil found in the NEG pipe downstream of SC tank
- From Hseuh – 8:30am today
- Case 1.  remove SC tank, install pipe	      **2days**
- Case 2.  remove obstruction , leave SC in place
- 		option 1: close, pump, leak check        **2 days**
- 			      (pressure rise)
- 		option 2: add N2 flush to option 1        **3days**
- Pump down today
- Beam (blue) at ~6pm
- Open yellow valve tomorrow ~mid day
- Hopefully back with yellow beam

## Impact of set-up/start-up

- Continue work with **blue** on owl – if possible
- Yellow set-up delay by another **2-3 days**
- This is still consistent with end of “2 weeks” set-up by **Jan 11** (collisions overnight)
- But this assumes that repair in Sector 4 goes according to schedule and there NO FURTHER MAJOR SYSTEM PROBLEMS