1 / 30

Tevatron Collider Monte Carlo

Tevatron Collider Monte Carlo. Version 2.0 (for Run II) Elliott McCrory August 29, 2003. Outline. What am I doing? Random Number Distributions Assumptions Collider parameters Randomizations How to end a store? Optimizing weekly integrated luminosity Future improvements

annice
Download Presentation

Tevatron Collider Monte Carlo

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Tevatron Collider Monte Carlo Version 2.0 (for Run II) Elliott McCrory August 29, 2003

  2. Outline • What am I doing? • Random Number Distributions • Assumptions • Collider parameters • Randomizations • How to end a store? • Optimizing weekly integrated luminosity • Future improvements • Improving Tevatron Reliability • Faster stacking • Run Coordinator Charts

  3. What Am I Doing? • Phenomenological (non-analytic) model of the Tevatron Collider Complex • Based on model of Run I, with Vinod, GPJ & others helping • McGinnis’s ordered me to revive it now. • Incorporate randomness • Downtime • For the Tevatron, stacking and the PBar Source • Variations in all realistic parameters • E.g., transmissions during a shot, lifetimes during collisions, uncertainty in exactly how many pbars we extract, etc…. • Search for the best criterion for intentionally ending stores • Based on these realistic assumptions and randomizations

  4. Current Features • V2: Represent Run II performance, today. • Many algorithms for ending stores • Can simulate 10,000 weeks quickly • In about 23 seconds on my Linux PC • Represents today’s performance • Easy to change to reflect “tomorrow’s” performance • Linux, C++ • Pretty good random number generator: drand48()

  5. Limitations • This is a phenomenological model! • L (t) = K  Np(t)  Npbar(t) / (εp(t) + εpbar(t)) 2 • K = C  KL H  B βγ / (2πβ*) • C: Constant kludge factor, = 32.5 • Adjusted globally to give today’s number for L (t). • KL: Longitudinal factor, = 0.8 • H: Variable hourglass factor, ≈ 0.5 ± 0.05 • B: Number of bunches, = 36. • K = 2223 ± 10% • Downtime over 24 hours is not considered. • Performance in the model does not improve • Just random fluctuations around specified performance.

  6. Unix’s drand48(), My RandomLinear RandomLinear(2.0, 12.0) RandomLinear(0.0, 5.0)

  7. RandomGaussian Distribution <x> = 2.0 σ= 5.0 100,000 samples SKIP

  8. RandomGaussian RandomGaussian(2.0, 5.0) RandomGaussian(<x> = 0, σ= 1) SKIP

  9. Also (not shown) RandomBoolean RandomLikely Product of these two distributions (0, 5, 2) and (-2, 12, 8)

  10. Stacking rate: 12*(1-S/300) [mA/hr] Stacking off: -0.001*S [mA/hr] Luminosity Lifetime I(p), I(pbar), ε(p) ε(pbar) Each grows by 7/sqrt(1+ (t+6)**2) Randomization Assumptions … Collider Parameter Assumptions

  11. Typical 2-week period for Target Stack Size = 170 Stack Size (mA) Stacking downtime Dropped stacks Lost store Luminosity (E30) Day number

  12. Lifetime Comparisons Four typical, simulated stores Luminosity, E30 Two recent, real stores Hours into the store

  13. Algorithms for Ending a Store • When one of the following exceeds target: • Stack Size • Store Duration • Integrated luminosity of the store • Instantaneous luminosity falls too low. • When 2 or more of these are satisfied • “Expected Luminosity” vs. luminosity now • Ratio • Difference • Etc.

  14. Test: Search for the Best Target Stack Size • If stack is lost, will stack to a reasonable stack size and shoot • Reasonable = 100 mA • Tevatron up time varies over several runs • 94% per hour to 99% per hour • For example, the probability a store lasts 20 hours is: • (0.96)20 = 0.442 • (0.99)20 = 0.818 • Charts and tables … • Optimization, downtime, RC tables and charts, etc.

  15. Run 5000 Weeks, using “Target Stack Size” Tev Up Fraction: 0.99 Up: 0.98 Up: 0.97 Average Weekly Integrated Luminosity, 1/nb Up: 0.96 Up: 0.95 Up: 0.94 Target Stack Size, mA

  16. Recovery time after lost store: RandomLikely(1.0, 24.0, 10.0) Tevatron Uptime per Week vs. Target Stack Size 0.99 0.98 Hours of store per week 0.97 0.96 0.95 0.94 Target Stack Size

  17. Fraction of Stores Lost vs. Target Stack Size 0.94 0.95 0.96 0.97 0.98 Fraction of stores lost 0.99 This is the best way to set the UpTime parameter Target Stack Size

  18. Run Coordinator Data: Per Store (T=200 mA)

  19. Run Coordinator Parameters, T=170 mA, Tev Up: 0.96

  20. Run Coordinator Charts Initial Luminosity Shot Number Stack Size

  21. More Run Coordinator Charts

  22. More Esoteric Stuff • Different end-of-store algorithms • “Luminosity Potential” • Startup after a dropped store • “Reasonable Stack” vs. Target Stack • “Reasonable Stack” in the context of “Luminosity Potential” • Better stacking

  23. Luminosity Difference or Ratio Cut • Use chart, here. • Two ways to end store (different runs): • When difference between the expected luminosity exceeds some constant, L. • When the ratio between the expected luminosity and the current luminosity exceed some constant, V. Expected Luminosity Initial Luminosity, E30 50 recent stores Stack Size, mA

  24. Algorithm to End Stores on the Luminosity Difference 0.99 Average Luminosity per Week, 1/nb 0.98 0.97 0.96 0.95 0.94 Value of the constant L: Expected Luminosity Difference

  25. Algorithm to End Stores on the Luminosity Ratio 0.99 0.98 0.97 Average Luminosity per Week, 1/nb 0.96 0.95 0.94 Value of the constant V: Expected Luminosity Ratio

  26. Reasonable Startup Stack Size? Startup Stack Size: 40, 60, 80, 100, 120, 140, 160 Average Weekly Integrated Luminosity, 1/nb Tevatron Uptime: 0.96 ∴ Wait to get a good stack after a lost store Target Stack Size, mA

  27. Startup Stack Size and Luminosity Potential (Ratio) Startup Stack Size: 40, 60, 80, 100, 120, 140, 160 Average Weekly Integrated Luminosity, 1/nb Tevatron Uptime: 0.96 Lum(Stack now) ≈ 4*(Lum now); Startup Stack Size: Less important. Allowing studies & accesses Target Stack Size, mA

  28. Stacking rate @S=0: 18 mA/hr 0.99 0.98 0.97 0.96 Average Weekly Integrated Luminosity, 1/nb 0.95 0.94 Target Stack Size, mA

  29. Compare 18 mA/hr and 12 mA/hr S=0 rate: 18 mA/hr Average Weekly Integrated Luminosity, 1/nb 12 mA/hr Tevatron Up: 0.96 Target Stack Size, mA

  30. What’s Next? • Fix problems found here • Give more formal talk to Shot Analysis Meeting • Incorporate Recycler • Study various transfer scenarios • I need guidance! • Make it usable by others? • Web interface? • Access to source?

More Related