Dave Hitlin First BaBar Spokesperson! - Stanford University · Dave Hitlin – First BaBar...

Dave Hitlin – First BaBar Spokesperson!

Stew Smith Princeton University January 13 2016

Panofsky Priize Symposium for Jon and Dave SLAC January 13, 2016 1

Acknowledgments

I joined BaBar a bit late, but with the same physics interests as BaBarians. The leadership of BaBar and SLAC immediately made me feel welcome, and have made the past 20 years more exciting, pleasant, and satisfying than I could ever have imagined.

For this, my deepest thanks to D. Leith, V. Lüth, B.Richter, J. Seeman, U. Wienands, M. Sullivan, all the PEP II/ BaBar community, and most of all, of course, to our honorees.

Among other things I would especially like to thank Dave for:

Approving my rare K experiment at BNL in 1983 with encouragement.

Welcoming this Johnny-come-lately into BaBar and supporting the new DCH team so strongly.

Giving little Princeton the privilege of hosting one of the 4 transformational physics workshops that produced the famous and influential BaBar physics book (with Rome, Paris and L.A).

Trusting me to replace the irreplaceable J. D. as technical coordinator in 1998.

Helping motivate and reassure the physics team to publish the sin2b discovery independently from Belle, and publish it FIRST!

Panofsky Priize Symposium for Jon and Dave SLAC January 13, 2016

Introduction

I’m charged today to deal with Dave’s 6 years as spokesperson, but clearly there was a prologue to this saga. BaBar did not just appear “fully formed!”

Looking back, it’s hard to realize how complex and challenging BaBar was, and yet how quickly it advanced:

Just over 5 years from the formal beginning of the collaboration in December 1993 to logging first events in May 1999.

Perhaps even more amazing, BaBar was taking data < 5 years from the LOI, and only 4 years from approval of the TDR (> 600 pages).

How was this possible? KEK-B and Belle had started significantly sooner but somehow PEP-II and BaBar caught up. We shall see ….

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B physics in the 80’s and early 90’s

Experimentally, discoveries in the 80’s of the relatively long B lifetime, and later B B mixing, generated great excitement that CP violation may be observable in the B meson system.

Theoretically, the Cabibbo-Kobayashi-Maskawa (CKM) picture allowed CP violation via a complex phase in the charged-current quark couplings. Could not account for cosmological asymmetry.

Increasingly, indirect evidence from K and B decays suggested there may be large observable CP effects.

A high-luminosity asymmetric e+e- B Factory, feeding a high-resolution detector, could

revolutionise the field!


New capabilities in collider and detector were essential to study CPV

Need a lot of reconstructed B’s and low backgrounds: e+e- Y(4s), which decays 100% to correlated B B pairs in a

1- state, appeared extremely attractive

• However, >1033 luminosity needed, cf a few x 1031 achieved at Cornell.

Very small part of cross section at hadron machines, even at TeVatron.

Need to measure decay times with ~1 ps resolution. 1- correlation at Y(4s) washes out time-integrated asymmetries

In CM, decay length is too small to measure (19 microns)

Asymmetric e+ e- collider at Y (4s) CM energy (10.58 GeV) would lead to ~250 micron decay lengths in the lab.

Measurable with a silicon tracker!

Need good particle identification to determine flavor of decaying states and correctly reconstruct events


Some of the challenges for BaBar

New technologies: high risk, need for intensive R&D. DIRC – Never been done before.

SVT – from vertex detector to tracker, tight schedule

Computing: real-time reconstruction, Object Oriented structure, huge data set, distributed facilities

Pushing established technologies beyond state of the art: compactness, resolution, rate capability, etc. DCH – small cell, digitize signals on endplates

EMC – resolution, mechanics, QC, etc.

IFR – production, QC and QA of a vast system under a brutal schedule.

Competition, both in US and around the world. ~ 20 efforts, but only funding and manpower for one B

Factory outside Japan.

BaBar secured the strongest army and resources, as an intrinsically international effort from the beginning.

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Some of BaBar’s secret weapons

The PEP-II-Linac complex at SLAC!

Hard core of talented scientists with a powerful, unshakeable belief in and vision for B physics and CP violation, even though the SSC was precluding other major initiatives. Necessity led to invention, real work ensued, so BaBar would

be ready should an opportunity present itself!

Several high-quality workshops produced a sophisticated

understanding of the requirements, and conceptual designs

to meet them.

Serious R&D efforts were addressing the main detector

issues.

An extraordinarily strong set of capabilities and expertise were ready and able in Europe and the US.

All was in place by 1993 …

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One of the several workshops from 1988 to 1992, whose many-hundred-page insightful reports on physics capability, backgrounds, detector concepts and requirements, laid a firm foundation for BaBar, as did similar workshops for PEP-II. Note:The foreword and introduction by David Hitlin expose him as a prime instigator, in cahoots with Jon Dorfan, David Leith and others.


BaBar hits the ground running!

October 1993:

SSC is cancelled by Congress

DOE selects SLAC to build a $170M asymmetric B factory, and a $62M detector. “Believe!”

• $62 M not enough! ~$30 M non-US contributions needed.

SSC scientists begin returning to universities and national labs; some have strong interest in a B Factory, notably Vera Lüth.

Collaboration is launched with lightning speed:

Inauguration meeting Nov 30-Dec 3, 1993.

Eight collaboration meetings in 1994.

Dave Hitlin is elected spokesperson July 1994.

LOI approved July 1994; TDR approved March 1995.

Technology choices made to allow detailed design to proceed:

• DIRC over Barrel Aerogel or RICH; RPC’s over LST’s.

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9


BaBar Management Structure

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BaBar under stress: 1995-96

Review committees are formed to oversee the project.

DOE “Lehman” committee for cost and schedule.

SLAC Director’s Technical Committee (M. Gilchriese, chair)

International Finance Committee

They point out problems with schedule, funding profile, and technical issues.

Schedule is “extremely aggressive, success-oriented, etc.”

Drift Chamber runs into funding and technical problems.

Procurement schedules are terribly tight for EMC CsI, SVT “Atom” chip, and DIRC quartz bars,

Vendors find it difficult to meet specs.

Computing is seriously under-resourced.

SLAC, BaBar and the funding agencies work together to bring success.

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The Technical Review committee delivered lots of highly effective tough love

OK, your SOB looks great.

But where’s your quartz??


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Lehman Review, Jan ’98


DOE Lehman Review, Jan ‘98


UPGRADES: Dave Hitlin commissioned “the

Schindler Committee” in 1999

Please evaluate our plans to respond to PEPII luminosities increasing from the current level of 2 1033 to 1034; and comment on the credibility of the projected costs.

In particular, please evaluate and comment on:

1. The computing model: CPU, disk, tapes, capability, access, etc.

2. The Instrumented Flux Return (IFR): performance, prognosis, and planned improvements.

3. Upgrade plans for the detector systems, front end electronics, DAQ, and the trigger, particularly the rejection rates for the L1 z trigger

4. R&D on detector aging and performance improvements

5. Schedule for replacing SVT modules, radiation damage tests, and schedule of R+D for a later replacement of the SVT.


Nov 2000 Technical Review on Upgrades, conclusions

Plans and estimates for most of the detector improvements are sound, and should proceed as presented. Leave Calorimeter, DIRC, SVT as is.

Speed up Drift Chamber electronics and add z information to the level-1 DCH trigger

Muon system is a serious problem that must be quickly resolved.

Computing enhancements are generally well justified, but serious issues must be addressed, including cost. Multiple Tier-A sites present promising opportunity

More attractive to funding agencies than cash contribution to SLAC

New model for event store and prompt reconstruction should be considered


Factory operation gets underway beginning in May 2000

First run is great success: highly-professional, analyses produce excellent results for ICHEP00: Likelihood fits, fully-blind analyses to increase reliability and

precision.

B0 Mixing, Lifetimes, CPV (sin2b), etc. based on 10fb-1

30fb-1 and CPV discovery in July 2001 thanks to the outstanding work of the PEP-II staff and the BaBar collaboration


Integrated Luminosity and BaBar efficiency


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From Dave’s talk, ICHEP00

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One year later, 7/6/01

sin(2b) = 0.59 ± 0.14stat ± 0.05syst


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Dave and Martha at the Babar Dedication, August 1999


The Group of Seven: BaBar Spokespersons – Paris, 2010

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PEP-II breaks Lumi- nosity record, Sept ‘99

Penguins, Stockholm ‘08

I O C s H a E k P a 0 0

Ready for beams, April ‘99


BaBar Hair Styles: always in fashion!

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Stew, Jon, Dave BCP4,

Ise Japan, January 2001

Stew, Dave, Jim Cronin and Jon,

50th anniversary of CP Violation,

London, July 2014


Thank you Dave for all the outstanding physics and great fun!


Congratulations Jon and David! and thanks for your leadership on BaBar

All the best!

Natalie & Francesco


Central Drift Chamber s

So well deserved, so long in coming. a

Heartiest Congrats from David, Stew and the DCH Group!

Stringing in Vancouver

Installation into BaBar

. 2s p-K

separation


• Hadronic PID System is essential for P > 0.7 GeV/c. (dE/dx < 0.7 GeV/c)

• BaBar had DIRC barrel-only design. • Excellent performance to 4 GeV/c. • Robust operation. • Elegant mechanical support. • Photon detectors outside field region. • Radiation hard fused silica radiators.

The Outcome: The BaBar DIRC Thank you –we made it! Blair


The EMC

Thanks for keeping us on the Project straight-and-narrow! -The EMC Team

Data

MC corrected

MC un-corrected


IFC calls Technical Review for Oct ’00

Critical milestone for BaBar’s future.

What if we failed??

Combined with the Upgrades Committee report, this review served as the perfect driver for our long-range planning.

Investment in preparations and documentation for the review had a second purpose, to expedite the writing of a comprehensive NIM paper on the BaBar detector, edited by VERA LUTH!


Computing issues and upgrade

Prompt Reconstruction:

Huge amount of hard work in winter-spring ‘01 by many people in BaBar and SCS increased performance sufficiently to save the experiment. Linux boxes, multiple farms, etc.

Off Line: Data storage, access, processing, simulation, analysis. Huge cost of increased luminosity caused crisis in

2000.

Spurred consideration of distributed model: • Countries provide ‘in-kind’ computing support via large

“Tier-A” centers comparable to SLAC.

• Store and process complementary data.

• Provide convenient, efficient remote access


The solution: a pioneer Grid

French proposal at Dec ’01 IFC meeting:

Include computing resources in Operating Common Fund, with

algorithm to calculate credit for CPU’s, disks, tapes, etc.

To qualify, a Tier-A center must provide efficient access to all.

Everyone must contribute to producing the tools to make this

work.

Agreement reached at special IFC meeting (Paris, Jan 01).

New International Computing Steering Committee set up

Tier A set up in France, then in Italy, UK, and Germany

Ensured adequate computing for the balance of the experiment.

Engendered an even-stronger level of cooperation throughout the collaboration


Tracking Performance: Evolution of D 3 K0

S

(S Wagner)

8-series

~2.5 fb-1 10 Series

~2.5 fb-1

8-series

~2.5 fb-1


The well-oiled science machine.

BaBar becomes flagship accelerator experiment in HEP

Postdocs flood the faculties, new cohort joins the fun

Detector performance remains excellent, improvements proceed as proposed

IFR Group greatly expanded to replace end-cap RPC’s

Committee appointed to evaluate proposed options for replacing the barrel RPC’s. (LST option is chosen.)

Tremendous set of results for ICHEP02 in Amsterdam, followed by flood of refereed publications.

Pioneer Grid Computing is a big success, but Objectivity event store remains problematic.

New “Computing Model 2.”

Committee appointed in summer ’02 recommended Root-based system to be implemented by 2004.

Finished in 2003, a year ahead of schedule.

Dave Hitlin First BaBar Spokesperson! - Stanford University · Dave Hitlin – First BaBar...

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