Davis Leith Symposium: Early Years - Stanford University · Michel Davier Dec.12 2014 David Leith...

David Leith Symposium: Early Years

From Scintillators

to Bubble Chambers

to Wire Chambers

Michel DavierLAL, Université Paris-Sud, Orsay

Michel Davier Dec.12 2014 David Leith Symposium, SLAC 1


Caveat: through his long and productive career David worked with a very large number of collaborators (as demonstrated by the impressive list of participants at this symposium). Through this short report I will be able to mention only a few. My apologies!

The Glasgow University Cricket Team

From Hutchesons Grammar Schoolto Glasgow University (1959)


in the 50’s

Graduate in the Department of Natural Philosophy at Glasgow University


Experiment on photoproduction on protons near threshold on the 330 MeV electron synchrotron with a scintillator telescope4 papers published

Thesis adviser: Gething Lewis

1962

Postdoc at CERN (1962-1966)


• Joined Max Ferro-Luzzi group: a good practice in scientific rigor• First encounter with bubble chambers• Studies of K±p interactions: start of a long-standing interest of David• Productive period with 12 papers and many conference proceedings• Remarkable results on hyperon spectroscopy (early demonstrations

of SU(3) and the quark model)• First review paper with Bob Tripp, Adolf Minten, …

1964

David joins SLAC: physics with bubble chambers


• A young Associate Professor• Joins Joe Ballam’s group B• David gets involved in on-going activities…

- analysis of data taken at BNL (16 GeV -p interactions)- shake-down of monochromatic photon beam at SLAC

for further use with the 40” bubble chamber

• but soon wants to have his own line of research• starts a collaboration with Alvarez’s group at LBL

(Art Rosenfeld)• Exposures at Argonne with pions to improve situation

of N phase shifts and baryon resonance spectroscopy(hot topic then)

• Very elaborate analysis developed (K matrix) with PaulSöding and Roger Cashmore

• First David’s student was on this work (Barbara Levi)• Very successful program with 8 papers published

1966

A KL Experiment with the SLAC 40”HBC


• David also pushed an original program with the 40” bubblechamber to study KL interactions, with Wes Smart, Bill Johnson,…

• Innovative scintillator system for TOF• leading to 7 publications

From Bubble Chambers to Wire Chambers


• Bubble chambers are detectors with full solid angle coverage and good spatial precisionbut slow

• Event samples with high statistics, triggered in order to access specific processes with high sensitivity required fast electronic devices such as wire chambers

• David got involved very early with such detectors, following experience gained at LBLin Perez-Mendez group

• Spark chambers with magnetostrictive read-out were chosen (the famous wands, magic…)

• Important contributors were Fatin Bulos, Harvey Lynch, and Steve Williams

Wire Chamber Spectrometer #1


• First experiment was on photoproduction on nuclei with Burt Richter and Victor Perez-Mendez with his student Steve Williams

• A dependence determines the N total cross section• A good warmup with spark chambers

Wire Chamber Spectrometer #2


• This second experiment was on production by pions with Burt Richter• triggered by a sharp forward peak observed in photoproduction. • Blair Ratcliff and Brig Williams were students on this experiment

• Same sharp forward peak is observed in the right helicitycombination

Toward High Statistics Hadron Physics with Wire Chamber Spectrometers


• The photoproduction and experiments were a good starting point to plan for future activities

• It was also a good training ground for students and postdocs

• David immediately realized the power of wire chambers spectrometers to pursue more effectively his interest in hadron spectroscopy and dynamics

• Very low SLAC duty cycle was a priori not favorable compared to hadron machines• But David took up the challenge!• He initiated studies for a wide-aperture apparatus• While his vision of a very large spectrometer had still to wait for a while,

a new version with a reduced scope was an important step capableof providing unique results

• Thus a new two-prong experimental program started led by two newly appointed assistant professors in David’s group

E-75: spectroscopy with K± beams (Bob Carnegie)E-85: K± p elastic scattering (MD)

The E-75/85 spectrometer #3


• 13 GeV RF-separated K beam and beam instrumentation• Large aperture magnet 1.8 T• 13 magnetostrictive chambers• Proportional chambers• Large segmented Cerenkov counter

E-75 : K± interactions at 13 GeV


• A rich program of strange meson spectroscopy• Discovery of two 1+ states: K1(1270)K, K2(1400)K*

through PWA

Deck

K1 K1

K2K2Deck

• Evidence for a 0- state at 1400 MeV (?)• Dynamics of 2-body processes

E-85 : K±/±/p± p elastic scattering


• Obtain the C=-1 scattering amplitude by interference with the dominant C=+1 diffractive amplitude

measure particle and antiparticle cross sections on protons with large statistics and small systematics

• Dual absorptive model : cross over moves tosmaller t at higher energies

• 1mm spacing MWPC

New ideas and detector construction


• During this period David was constantly thinking of new ideas for developing the bestdetectors and equipment to achieve the physics goals

• The list of the projects he has initiated, pushed through and published is impressive:- wedge scintillator with high spatial precision- online Vidicon scanning system for bubble chambers- large aperture Cerenkov hodoscope- new digitizing and memory system for wire spark chambers- versatile high resolution beam position monitor- TOF trigger system for the 40” HBC- adaptable geometry low mass hodoscopes using cathode readout PC

• A good technical team to realize the projects: Al Kilert, Bob Friday, Don McShirley,Ken Mauro, Bill Walsh…

Moving on to LASS (some personal memories)


• LASS concept and physics studies started even before 1970 (with George Luste)• The story of the LASS adventure will be told by Bill Dunwoodie

• I had the chance to participate in lively meetings in David’s office (with tables somewhat crowded by preprints) in the technical design phase

• I was impressed by David’s strong leadership, yet in a friendly atmosphere,and his concerns over many detailed aspects (ex. discussion with John Alcornabout safety issues in case of a quench of the large solenoid: Boeing 747)

• Another occasion I still vividly remember is a (AEC, ERDA?) review in Fall 1974 where David presented the status of the project and I was given the task tojustify our interest in hadron spectroscopy. I used the quark model as an obviousframework, but was challenged by the reviewers on the basis that the SPEARresults had already disproved the model. Then came November 1974…

Friendships


• David created a unique friendly atmosphere in group B• So many activities going on in parallel• A multinational group• David’s efficient leadership, yet leaving freedom to his

collaborators, thus fostering their creativity

• Frequent occasions to meet outside the lab- Tuesday night seminars at David’s home- Friday night beer at the Dutch Goose

• David and Doreen legendary hospitality (also unique)• Ah, Doreen’s unforgettable Xmas Scottish shortbread….• The famous New Year party in their house….

Personal Friendship


• Our two families have enjoyed a good friendship for 45 years• Shared memories: citing David on another occasion

One of Doreen’s fondest memories, before her own grand-children arrived, was daily brushing the beautiful long hair of Eve and Diane, when their Mum and Dad had gone back to France on the death of Francoise’s father.

• My daughters Diane and Eve still remember as well• We value very much the Leith friendship

~ 1969 1974


Thank you David for sharing this very productive part

of your scientific life

1984

2010

Thanks to Ewan and Mandi Patterson (and Doreen!), Harvey Lynch, and Jean Dekenfor some nice pictures!

Davis Leith Symposium: Early Years - Stanford University · Michel Davier Dec.12 2014 David Leith...

Documents

Transcript of Davis Leith Symposium: Early Years - Stanford University · Michel Davier Dec.12 2014 David Leith...