Residual Radiation Cooldown: Main Injector Bruce C. Brown Fermilab All Experimenters Meeting 19 March 2012

Outline Data o Residual Radiation at Bar Coded Locations o BLM Data each 2.2 sec Main Injector Cycle Fit Residual Radiation using BLM data o Assume a set of half life values o Weight BLM data by half life, do linear fit (simple matrix inversion only) Identify Important Isotopes (activation study) Examine Cooldown Predictions o Collimator Area o ANU Operation o Effects from SeaQuest Operation 19 March 20122Bruce C Brown -- All Experimenters Mtg

Residual Radiation near MI Collimators 19 March 20123Bruce C Brown -- All Experimenters Mtg

Formulas for Fitting The BLM system records (for each monitor) a loss integral (LI) for each MI Cycle. We sum these over ten minute intervals (T s = 600 sec) – to quantas, LIj. For each isotope we sum these quantas weighted by the half-life The fitting hypothesis assumes that the measured residual radiation at measurement time, T M is a linear sum of the weighted quata sums over the set of isotopes The physics of the loss pattern and isotope production, loss monitor geometry, bar code monitor location geometry and Geiger tube energy response multiply to create one linear constant E I. 19 March 2012Bruce C Brown -- All Experimenters Mtg4

Losses LI232 Since Oct March 20125Bruce C Brown -- All Experimenters Mtg

Activation for MI Steel Samples (Normalized to BLM rate) Compare Normalized Activation of MI Steel Sample SampleHalf LifeAverageRatio daysShieldedUnshield /Average Shielded Br Co Cr Fe Fe Mn Mn Mn Na Sb Sb Sc-44m Sc Sc Sc V Sc

Residual Radiation w/ Fit at Q232D 19 March 20127Bruce C Brown -- All Experimenters Mtg

Cooldown Prediction – D230D 19 March 20128Bruce C Brown -- All Experimenters Mtg

Cooldown Prediction – Q230D 19 March 20129Bruce C Brown -- All Experimenters Mtg

Compare Cooldown Fits 19 March Bruce C Brown -- All Experimenters Mtg

Predictions for Nova Era Operation of the Main Injector Complex for the NovA era will achieve 700 kW operation by accelerating the similar intensities with higher repetition rates. The losses will be similar and much of the loss will be at the same locations. The weighted loss rate LW for any isotope will reach an equilibrium for the new rate at 2.2/1.3 of the current (nearly) equilibrium rate. Long Half Life isotopes will continue to build toward equilibrium. Measured Residual Radiation results from the sum of the specific activities, S A of produced isotopes weighted by geometry effects and the energy response of the measurement instrument (Geiger Counter). Since iron is typical of the materials we activate, we look at the chart of identified isotopes and see that the only long lived isotope not included in previous studies is Co-60 with a half life of Days (5.27 years). Comparing the ratio of S A for Co-60 with that for Mn-54 we predict that when starting a shutdown after achieving equilibrium, we expect 13.8/63.9 = 21.6% enhancement of the long lived components (ignoring differences in geometry or energy response). Planning for a long shutdown in the Nova era will be impacted primarily by the 70% higher loss rate (assuming same loss fraction) with little impact from build-up of long half life isotopes. 19 March Bruce C Brown -- All Experimenters Mtg

Activation Study for SeaQuest Observe Losses for Current Operation at 3E11 p Typical activation data and loss rates will predict residual radiation due to SeaQuest slow spill operation at 1E12 or at 1E13 ppp and expected repetition rate. Could try to use 8 GeV activation data but 120 Gev will be somewhat different physics and geometry Will wait for measurements, then scale with rate 19 March 2012Bruce C Brown -- All Experimenters Mtg12

Losses for Operation 8 – 11 March 19 March Bruce C Brown -- All Experimenters Mtg Beam21 LI520D LI522A LI521A

Typical Rates for 1E12 protons/cycle Assume we run 1 SeaQuest cycle per minute and take losses measured March 8-11, compare to 10 week average of some collimator region BLM’s 19 March Bruce C Brown -- All Experimenters Mtg Resonant Extract AreaCollimator Area Residual Radiation Measurements following a week or two of operation are needed

Acknowledgments This work had been built on the efforts of many individuals and groups at the lab. Some of them include:  Guan Wu (MI Dept) for Application Program Support  Operations and MI Department for vigilant tuning  APC Energy Deposition Gp (Nikolai Mokhov and colleagues)  Vernon Cupps (retired) for Activation Measurements  Everyone who contributed to the MI BLM System 19 March Bruce C Brown -- All Experimenters Mtg

References Some Console Applications for Displaying Main Injector BLM Measurements Residual Radiation Monitoring in the Main Injector with the ROTEM RAM DA Radiation Survey Meter Measuring correlations between beam loss and residual radiation in the Fermilab Main Injector.Measuring correlations between beam loss and residual radiation in the Fermilab Main Injector. Activation of Steel and Copper Samples in the Main Injector Collimator Region 19 March Bruce C Brown -- All Experimenters Mtg