Booster BLM Data

Device Descriptions Locations Trip Values
Monitoring Software Data Plots

Trip settings have been enabled on many of the Booster BLM's. This has been done in an attempt to limit losses in order to prevent excessive activation of the accelerator components. We expect both the values of the alarm settings and the number of BLM's involved to evolve with time, as we better understand the correlations between BLM readings and activation levels in the tunnel.

Device Descriptions

The ACNET devices to which the alarms have been applied are the B:BLxxx0 devices (where xxx is a 3 letter location description). These devices contain sums of the total losses recorded on all beam resets (event 10's) during the last 100 seconds and update every 17 seconds.

Locations

See BLM Location Descriptions for descriptions and photos of the placement of all relevant BLMs. Currently, upper limits are enabled on the following 60 BLM's:

Trip Values

The initial alarm values were obtained by simply doubling the average values recorded during a "typical" 3.5 hour p-bar stacking period that occurred between 19:00 to 23:30 on 14-Apr-2002. The following link lists the values used with any subsequent changes: "BLM Trip Setting History"

In order to determine better trip points, We have attempted to fit the Loss data to measured activation levels. The model used is a two-lifetime model with a correction for very short lived activation.
     Ai(t) = Ksi.Ssi + A1i.exp(-L1.T) + A2i.exp(-L2.T) + Ki.[ L1.S1(T) + L2.S2(T) ]
where: Ai(T) is the activation measured at location i and time T.
  Lx is the decay constant for isotope x;
  Ls = 9.24 (18F), L1 = 0.122 (52Mn), and L2 = 0.00229 (54Mn).
  Sxi(t) is a time weighted integration of the losses recorded by the BLM associated with location i during the time period t. The weighting function is given by exp[-Lx.(T-t)].
The remaining parameters are determined by the fit.

The results of the fits are displayed in the following plots:-

Monitoring Software

An application program is available on B88 to monitor past and present Booster performance with respect to these BLM's. Current performance is monitored via an SA which plots the current values of the B:BLxxx0 devices normalized to their alarm settings. This plot looks similar to the one produced by B89 for monitoring the Booster Chipmunks.

In order to monitor past performance, B88 can also be used to produce similar plots based on data extracted from the BLM2 data-logger.

Booster Performance

Each of the ~120 B:BLxxx4 and B:BLxxxD devices are data-logged. This enables us to monitor Booster performance with this system in a manner completely analagous to way it is done with the Chipmunks. For stable running periods, we record the average reading for each BLM and normalize it to the corresponding alarm maximum. The largest value thus obtained, is normalized to the beam delivery rate during that period in order to determine the maximum protons/hour that could have been delivered without tripping one of the BLM's. (A stable running period is a period of at least an hour in which neither the protons delivered per pulse nor the pulse rate varied by more than 5%. Stable periods are defined separately for x1D and x14 event types.

Long Term BLM monitoring ..

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