Discovery of the Upsilon and Bottom Quark - a personal reminiscence 40 years later

1. Discovery of the Upsilon and Bottom Quark - a personal reminiscence 40 years later Jeffrey A. Appel Fermilab Colloquium 31 May 2017

2. Now 40 years since announcement of the Upsilon discovery “The Upsilon meson (ϒ) is a quarkonium state (i.e. flavourless meson) formed from a bottom quark and its antiparticle. It was discovered by the E288 experiment team, headed by Leon Lederman, at Fermilab in 1977, and was the first particle containing a bottom quark to be discovered … mass about 9.46 GeV/c2 ” - Wikipedia S.W. Herb, et al. (1977). "Observation of a Dimuon Resonance at 9.5 Gev in 400-GeV Proton-Nucleus Collisions" (PDF). Physical Review Letters. 39: 252–255 (1977). Received 1 July 1977 J. A. Appel | Discovery of the Upsilon and B Quark

3. Check Out the Fermilab Web Site for an Excellent History Because of the importance of the upsilon discovery, there are excellent resources on the subject in the Fermilab archives, and excellent summaries on the web – the latter thanks in large part to John Yoh! http://history.fnal.gov/botqrk.html J. A. Appel | Discovery of the Upsilon and B Quark

4. Also, the AIP Lederman Interview and the IIT 20th Anniversary Celebration Also, check out the American Institute of Physics interview of Leon Lederman in their oral histories collection. https://www.aip.org/history-programs/niels-bohr-library/oral-histories/31388 And, for example, the proceedings of the 20th anniversary celebration at IIT, organized by Dan Kaplan. 20 Beautiful Years of Bottom Physics, IIT, June 29-July 2, 1997 http://capp.iit.edu/hep/b20.html and Proceedings (available from AIP Press) J. A. Appel | Discovery of the Upsilon and B Quark

5. Start with a quick look at an earlier Brookhaven result by a Collaboration led by Leon Lederman Observed dimuon production in p-nuclear collisions downstream of much shielding. Missed discovery of the J/y, made of a charm quark and antiquark. Problem of resolution because of scattering of muons in shielding upstream of detectors. Electrons would have been better (Sam Ting). J. A. Appel | Discovery of the Upsilon and B Quark

6. Also, … “Bump” was very wide. “Bump” was at the edge of the acceptance which was poorly understood – per Bernie Pope, Nevis thesis student on the experiment. Much less capable software for simulation and much less computing power then than now. As an aside, Peter Limon at Nevis proposed redoing the experiment with electrons, but Nevis Labs would not support it. J. A. Appel | Discovery of the Upsilon and B Quark

7. Next Step was at Fermilab: E-70 E-70 Proposal Authors: W. Lee, L. M. Lederman*, J. Appel Columbia University M. Tannenbaum Harvard University L. Read, J. Sculli, T. White, T. Yamanouchi National Accelerator Laboratory * Correspondent J. A. Appel | Discovery of the Upsilon and B Quark

8. E-70 – Proposal Date: June 17, 1970 “Study of Lepton Pairs from Proton-Nuclear Interactions; Search for Intermediate Bosons and Lee-Wick structure“ “We propose to observe lepton pairs emerging from high energy proton-nuclear collisions. Large effective mass pairs probe the hadronic electromagnetic structure. The continuum mass spectrum will be measured and any resonant structures in the mass range up to ~ 28 GeV will be detected with great sensitivity. The data provides a prediction, via Conserved Vector Current theory, for the production cross section for weak vector bosons and these are also sought in the mass range ~ 8-28 GeV. We also propose an initial photon-electron beam survey at high transverse momentum which is also a W-search with good sensitivity.” J. A. Appel | Discovery of the Upsilon and B Quark

9. E-70 Proposal Objectives 1. To observe the differential cross section for emission of pairs of effective mass Me+e- up to the kinematic limit of ~ 28 GeV. 2. To observe structures in the dilepton mass distribution with a mass resolution of the order of 1%. In the particularly interesting case of the Lee-Wick theory [a version of quantum electrodynamics ], the heavy photon pole would be easily observable if it exists and its mass is less than 30 GeV. 3. To search for the charged intermediate vector meson via its leptonic decay mode. The cross section for production of intermediate bosons is provided by the electromagnetic pair distribution (to within a factor of 2 or 3) via cvc. J. A. Appel | Discovery of the Upsilon and B Quark

10. Yamaguchi Prediction and BNL Limit Y. Yamaguchi, ilNuovoCimento, 43, 193 (1966), related vector boson production to virtual-photon production probability (measured via lepton-pairs). It was this calculation that led to a limit near 3 GeV for the Z0 boson mass using BNL data. J. A. Appel | Discovery of the Upsilon and B Quark

11. E-70: Proposed as a Three Phase Effort Phase 1 Beam Survey, a single-arm measurement of single photons. Phase 2 Beam Survey and W/Z Search, a single-arm measurement of single leptons (e and m). Phase 3 The two-arm, lepton pair experiment – eventually became E-288. [Actually, added a Phase 0 while waiting for completion of the single-arm detector, putting a lead glass detector into the collision hall. (failed to work in high backgrounds, even though the lead glass was insensitive to neutrons from the beam dump).] J. A. Appel | Discovery of the Upsilon and B Quark

12. The Single-Arm Spectrometer – E-70 Single-arm detector used the techniques eventually used for the two-arm experiment: Incident proton beam, small nuclear targets (for simple momentum measurement) Upstream beam dump Open aperture for e’s, absorber for m’s Charged-particle tracking with wire chambers Lead glass and steel- scintillator calorimeter for particle identification Vertical bending magnet to get out of the neutral, secondary beam and measure charged-particle momenta. J. A. Appel | Discovery of the Upsilon and B Quark

13. Physics Environment before the Fermilab Accelerator Era Electroweak Theory unconfirmed. Highest priority was to observe W/Z boson. Neutrino production was thought to be the most direct and cleanest experimental signature. Brookhaven results suggested that W,Z heavier than 3 GeV/c2. Extrapolations of hadron rates vs pT from Brookhaven were proportional to e-6pT. Even QED had alternative theories (e.g., Lee-Wick theory with boson B). J. A. Appel | Discovery of the Upsilon and B Quark

14. Why does a Heavy Mass 2-Body Decay Lead to a Peak in pT? Consider the heavy object decay in its center of mass, decaying to two light particles. The two particles go out back-to-back uniformly in all directions (uniform in phase space). Think of momentum vectors uniformly distributed on a sphere, each = M/2. Compress the sphere, projecting the surface onto a plane in the forward direction. The greatest density will appear peaked at the maximum momentum; i.e., pT = M/2 This is called the Jacobean enhancement; the peak a “Jacobean peak”. J. A. Appel | Discovery of the Upsilon and B Quark

15. Backgrounds and 10-4 rule for lepton/hadron rates “Assuming our counters survive and succeed in counting electrons we will have a distribution in PT at several angles (say 50, 70, 90, 110 mr) and for several machine energies (say 500, 300 and 150). We expect the W to show up as a shoulder or bump on a rapidly decreasing background. This bump wiII be very near the value PT half the mass of the W.” Backgrounds were orders of magnitude worse than estimates based on extrapolations from Brookhaven observations. [Saw e’s and m’s at a level of 10-4 that of p’s]. “Of course if no bump is observed, we need the pair experiment to interpret the results and to look harder [using the Yamaguchi prediction technique].” J. A. Appel | Discovery of the Upsilon and B Quark

16. Two Angles and More (missed J/y and charm quark) E-70 measured 50 and 83 mr angles and stopped to consider the next step. Could pursue the origin of the surprising 10-4 ratio of leptons to hadrons. Wanted to go to the two-arm apparatus; but funding was not available (remember the neutrino priority, for example) and we settled to make single-arm measurements at two additional angles. Regretted the decision later, since we missed discovery of the J/y and charm quark (second , even third time for poor Leon!). J. A. Appel | Discovery of the Upsilon and B Quark

17. E-70 Tries to See the J/y Given the J/y discovery at SLAC and Brookhaven, E-70 made a first, crude attempt to observe muon pairs. We placed scintillator behind the concrete shielding in place of a true second-arm apparatus. We did see a few coincidences between these scintillation counters and the single arm muons – consistent with the J/y. J. A. Appel | Discovery of the Upsilon and B Quark

18. Needed new approval for E-70 Phase III Largely reproduced the text from the original E-70 Proposal. Proponents list updated on the cover page, but the next page reproduced the original list! J. A. Appel | Discovery of the Upsilon and B Quark

19. J. A. Appel | Discovery of the Upsilon and B Quark

20. Electron Pairs Proved to be Hard August, 1975 First electron pair setup (discovery of superbuckets in the accelerator!) Limited incident beam and collision rate. J. A. Appel | Discovery of the Upsilon and B Quark

21. Oops Leon Electron signal - John Yoh fast search Three events in one weekend Wilson request for daily count on lab TV monitors Paper J. A. Appel | Discovery of the Upsilon and B Quark

22. Oops Leon Electron signal - John Yoh fast search via the “bicycle on-line”. Three events at a mass near 6 GeV in one weekend! Collaboration excitement and draft of the “discovery” paper. Wilson request for daily count on lab TV monitors (rejected). “We report preliminary results on the production of electron-positron pairs in the mass range 2.5 to 20 GeV in 400-GeV p-Be interactions. 27 high-mass events are observed in the mass range 5.5-10.0 GeV corresponding to σ=(1.2±0.5)×10−35 cm2 per nucleon. Clustering of 12 of these events between 5.8 and 6.2 GeV suggests that the data contain a new resonance at 6 GeV.” Phys. Rev. Lett. 36, 1236 (1976) Received 28 January 1976 J. A. Appel | Discovery of the Upsilon and B Quark

23. Deciding on a Name Meeting of those at Fermilab at that time in the Snake Pit Conference room on a Saturday morning. Perhaps a half dozen names suggested: Leon Wilson NAL (or NALon) List of unused Greek letters: Jeff Weiss's list Only iota, theta and upsilon options considered. Upsilon ϒ was selected, unanimously (or nearly so if not) J. A. Appel | Discovery of the Upsilon and B Quark

24. Upsilon ϒ The upsilon name appeared only in a footnote: ** We suggest that a provisional designation of this object be ϒ (UPSILON): ~(6.0) from ϒyhlon, "the lofty one". from the preprint FERMILAB-Pub-76/19-EXP 7100-288 9 We suggest the name ϒ (upsilon) be given either to the resonance at 6 GeV if confirmed or to the onset of high-mass dilepton physics. as it appeared in Phys. Rev. Lett. 36,1236 (1976) J. A. Appel | Discovery of the Upsilon and B Quark

25. What’s It’s Like Waiting for Confirmation PRL publication delay; referee claimed that we overestimated the statistical significance. Continued running did not see excess events at the same rate. Then, no di-muon signal and thoughts of a possible lepton non-universality. Two events near 9.5 GeV - John Yoh predicted an additional resonance there and put a 9.5 GeV-labeled bottle of champagne in the portakamp refrigerator in reserve. J. A. Appel | Discovery of the Upsilon and B Quark

26. APS Meeting in NYC February 2-5, 1976 Winter APS meeting presentation - did Leon know? David Hom gave a ten-minute talk, buried in the program But at an APS press conference on the most interesting new results at the meeting, I represented E-288. Martin Perl (spokesperson of the tau-lepton experiment) was there too, and supported upsilon as third-generation quark to match his third-generation lepton. . J. A. Appel | Discovery of the Upsilon and B Quark

27. Famous One-Page White-Paper “Proposal” J. A. Appel | Discovery of the Upsilon and B Quark

28. The Real Goals in That “Proposal” Aside from the basic spectra measurements: Search for structures in the above spectrum, publish these and become famous, e.g., Wo, Bo. 5. Extend the Experiment #70 of single leptons in the double arm arrangement, i.e. the W+- etc. Publish these and become famous. J. A. Appel | Discovery of the Upsilon and B Quark

29. Super E-288 Muon Apparatus Layout J. A. Appel | Discovery of the Upsilon and B Quark

30. Finding Enough Beryllium – Two Metric Tons Enlisted the aid of the local ERDA officials, who, at first, registered an incredulous gasp at the quantity requested -- two metric tons. But ERDA manager Don Bray and Irv Schau entered the game and searched ERDA's resources to the limit. The hunt finally led to Oak Ridge, Tennessee, where leftover beryllium from an Oak Ridge project was discovered. The diligent cooperation of all of the institutions involved led to a long-term loan of the precious metal to Fermilab for the experiment. Bob Adams (L), Safety, Bill Thomas, Proton, check in beryllium shipment J. A. Appel | Discovery of the Upsilon and B Quark

31. View of the E-288 Detector and Team J. A. Appel | Discovery of the Upsilon and B Quark

32. Dimuons proved to be the route to a “quick” discovery “After a few weeks with the new configuration, we found that the probability to produce muon-antimuon pairs peaked sharply at about ten times the proton mass.” “We were observing a new quark.” Dan Kaplan, who worked on the upsilon for his thesis, was a SUNY-Stony Brook graduate student At the time. However, it’s worth noting that before we had much data, the shunt used to measure the current in the analysis magnets melted and caused a fire in the local cables – and a lot of acrid smoke. We made a heroic effort to clean the exposed electronics to avoid the likelihood of failures. J. A. Appel | Discovery of the Upsilon and B Quark

33. E-288 Collaboration It took about 20 physicists and technicians, from Columbia University, Fermilab and the State University of New York at Stony Brook, to find the bottom quark. Left to right: Dave Hom (Columbia University), Chuck Brown (FNAL), Al Ito (SUNY), Bob Kephart (SUNY), Koiji Ueno (FNAL), Ken Gray (FNAL), Hans Sens (Columbia University), Dave Snyder (Columbia University), Steve Herb (Columbia University), Jeff Appel (FNAL), Dan Kaplan (SUNY). Collaboration members not shown in these photos: Leon Lederman, John Yoh, (Columbia University), Bruce Brown, Walter Innes, Taiji Yamanouchi (FNAL), Hans Jöstlein (SUNY). J. A. Appel | Discovery of the Upsilon and B Quark

34. Will the Real Upsilon Please Stand Up? S.W. Herb, et al. (1977). "Observation of a Dimuon Resonance at 9.5 Gev in 400-GeV Proton-Nucleus Collisions" (PDF). Physical Review Letters. 39: 252–255 (1977). Received 1 July 1977 J. A. Appel | Discovery of the Upsilon and B Quark

35. Footnotes from the ϒ Discovery Paper 6 Following Ref. 1, a reasonable designation for this enhancement is ϒ(9.5). 7 We note that the 9-10 GeV mass bin in the e+e- and m+m- spectra previously published by this group (Ref. 8) shows an excess of events, consistent with the statistically more significant results here. If we add our preliminary unpublished e+e- data to our published e+e- yield (Ref. 1), the spectrum contains a cluster of 6 e+e- events near 9.5 GeV where about 5 events would be expected on the assumption of m-e universality J. A. Appel | Discovery of the Upsilon and B Quark

36. Making the Discovery Known Paper submitted to Physical Review Letters – Accepted without review at the request of Edwin L. Goldwasser under policy announced 26 April 1976. Steve Herb gave discovery special seminar at Fermilab on June 30th. Leon Lederman announced the discovery of the upsilon at the 1977 summer conferences: at the EPS conference in Budapest, and the Lepton-Photon conference at Hamburg. J. A. Appel | Discovery of the Upsilon and B Quark

37. Confirmation at DESY in Hamburg, Germany The search for the ϒ resonance at the "Double Ring Store" (DORIS) at DESY was made in 1978 after the energy of the beams was raised to 5 GeV each. By scanning the center of mass energy range from 9.35 GeV upwards, the PLUTO and DASP2 experiments (April - May 1978) found a very narrow resonance at 9.46±0.01 GeV (in 1977 at the Tevatron the peak was at 9.5±0.2 GeV), with a width consistent with the machine energy spread of 8 MeV. DASP2 J. A. Appel | Discovery of the Upsilon and B Quark

38. Worry About Too Much Text on Slides Granddaughter Sonia’s Mothers-Day Gift to Her Mother J. A. Appel | Discovery of the Upsilon and B Quark

39. After the Discovery Quick acceptance of upsilon as b-quark bound state. Expectation that top would be 3 to p times as heavy (based on the ratios of the masses of the strange quark (~0.5 GeV), charm quark (~1.5 GeV), and bottom quark (~4.5 GeV). Japan built a collider to discover the top quark: the KEK e+e− collider TRISTAN – √s=52 GeV TOPAZ detector, e.g., exclusion limit for mt = 25.8 GeV) J. A. Appel | Discovery of the Upsilon and B Quark

40. Gifts from E-70 and E-288 to Fermilab Perhaps you have walked by these objects in the Gallery on WH-2X. Cracked Lead-Glass Block The Magnet Shunt J. A. Appel | Discovery of the Upsilon and B Quark

41. Quark Names Before wide acceptance of “top” and “bottom” to name the 3rd-generation quarks, following the first quark generation names of “up” and “down”, Names “truth” and “beauty” suggested after “strange” and “charm” names of the 2nd-generation quarks J. A. Appel | Discovery of the Upsilon and B Quark

42. As I liked to say, We were working on the search for truth and beauty. And that’s the story of the upsilon discovery as I remember it. J. A. Appel | Discovery of the Upsilon and B Quark

43. Abstract The discovery of the upsilon particle at Fermilab occurred forty years ago. The new particle helped spur acceptance of the three-generation quark-lepton standard model and the search for the top quark. The discovery itself had a surprising history which will be recounted in this colloquium, including some untold stories from inside the collaboration. J. A. Appel | Discovery of the Upsilon and B Quark