# Presentation: 758220

## Setting BLM Limits in the Booster

- The Booster is now delivering all the protons needed by the collider program, and about 40% of the protons needed by MiniBooNE.
- We are physically capable of delivering all the protons requested, but we are limited by the loss limits we have set in the tunnel:
- Rad damage issues
- Worker safety issues.
- Generally, we’re doing very well at controlling losses in the Booster
- We’re putting roughly 10 times as much beam through the Booster as before MiniBooNE came on.
*Average* activation has only risen by a little over a factor of 2.
- However, we’ve been seeing some disturbing levels of activation, particularly at RF cavities.
- This is getting noticed, and if we don’t address the problem, someone else will address if for us.
- Many of our problems come from loss limits which are set too high.
- We should be able to reduce several of these without decreasing the total intensity.

## What Limits the Booster

- Present rate

- Maximum based on trip point

- Also limit total booster average power loss (B:BPL5MA) to 400W.

- Irreducible loss created by the notch

## How Limits Were Set

- Individual Loss Monitors:
- Limits were set to twice measured values during typical “good” stacking, before MiniBooNE.
- When MiniBooNE came on line, these were all increased by 50%
- Individual limits have been adjusted by hand
- Raised if it was felt they were too sensitive
- Lowered when high activation was seen (example: L24)
- Power meter:
- The limit was NOT based on the SNS 1 W/m number.
- 250W was found to be a decent limit during pre-MB stacking.
- We began to increase it when MiniBooNE came on line, with the plan of eventually hitting 500W.
- In December 2002, we were at 450W, and found that the activation in the tunnel was very high, so we lowered it to 400W, where it will stay until...
- After the summer shutdown, when the new collimator system renders it useless.

- Another reason we must improve the individual loss monitors!!

## How are we doing? (Really well, actually)

- Energy lost per proton, good, BUT

- Since MiniBooNE

- Last 2 Weeks

- Unstable Running

- Must get better at recovering from shutdowns!!!

- Power loss (W)

- rate (p/min)

## Examining High Radiation Areas

- I picked four surveys:
- 8/28/02: Before MiniBooNE started running seriously
- 4/10/03 and 4/29/03:  During some of our best running to date
- 6/17/03: recent access
- All of these had similar cooldown times, so I didn’t apply any cooldown correction
- I corrected data to mR/hr as follows:
- 1ft measurement: no correction
- Contact measurements EXCEPT short straights: divide by 5
- Short strait measurements: divide by 2 (this is because the contact point is on the stand, not the *beampipe*)

## High Radiation Areas (> 100 mR/hr@1ft)

- alignment and tuning

- injection tuning

- extraction

- collimator?

- notch

- limits too low

- extraction

- tuning

## Tuning Sensitive Areas (>100 mR/hr and 25% worse on last access)

## Typical “best” Running

- Notch loss – irreducible, should be our limiting loss

- Anything averaging below 20% of trip point probably has too high of a limit

- L3

- L13

## Short Term Recommendations

- Decrease limits around injection by ~25%
**S21: 900->675**
**L22: 300->225**
**S22: 900->675**
**L23: 150->115**
**S23: 300->225**
**L24: 225->170**
**S24: 300->225**
**L1: 16->12**
**S1: 900->675**
**L2: 23->18**
**S2: 900->675**
- Cut some other high limits roughly in half:
**S10: 900->450**
**L12: 75->40**
**S12: 600->300**
**L15: 250->150  (Done)**
- Bypassing limits:
- No limit may be bypassed during normal operation.
- At the request of Booster experts, at most 3 (??) individual loss limits may be bypassed for at most 1 hour.  Both the bypass and the restoring of the limits should be duly noted in the Elog.
- The power loss limit should never be bypassed.

## On the Horizon

- During the shutdown:
- We will stretch out the L3 dogleg region.  This should improve the lattice and decrease losses.
- We’re (finally) installing a collimation system. This should further reduce uncontrolled losses, HOWEVER
- Once the collimation system is installed, the power loss meter will not be a good measure, so we will have to rely more on the individual loss monitors.