Charles Supper Award Talk 2-Dimensional X-ray detectors – What do we really want and how can we build it ? Ron Hamlin August 1, 2012

X-ray diffraction Max von Laue discovered X-ray diffraction by crystals when he and his assistants directed a beam of X-rays at a crystal of copper sulfate and recorded the diffraction pattern on a piece of film. 1913 W.L. Bragg reported the first crystal structure, the structure of Sodium Chloride

Basic Data Collection Geometry

An X-ray Diffraction Pattern recorded on film A rotation photograph From Blundell and Johnson 1972

Visual intensity estimation Precession film of Phosphorylase From Blundell and Johnson p.156

But eyeball estimation of spot intensities took time and, at best, had limited accuracy. Was there a better way ?

Concept drawing of a film scanner Rossman, Methods in Enzymology 1985, p. 242

Optronics P-1000 film scanner Photo provided by Dieter Schneider, Brookhaven National Laboratory

But data collection with film still required long x-ray exposures But data collection with film still required long x-ray exposures. And then developing film had to be done very carefully to get the accurate results that film scanners were capable of. An excellent paper on the careful, accurate use of film scanners is one by Walter Phillips and George Phillips, J. Appl. Cryst. (1985). 18, 3-7

Electronic detectors Early work was started in the late sixty’s and early seventy’s to automate the whole data collection process and use electronic detectors. This led to the development of commercial diffractometers.

Single crystal diffractometer Robert Sweet, Methods in Enzymology 1985

Picker Diffractometer c. 1971

Diffractometer: automatic but measured only one hkl reflection at a time

Omega scan of a single reflection

By 1970 Rotation and precession cameras were in use for obtaining diffraction photos on film. Film scanners were in use for optically scanning these films and extracting integrated intensities. Diffractometers were in use that were equipped with single point X-ray counters for automatically measuring one reflection at a time.

Also By spring of 1970 In June of 1970 at University Of California, San Diego I had just finished the required 2 years of Physics graduate courses and passed the Physics departmental exams. In June of 1970 I showed up in Xuong’s lab looking for a thesis project to start my Ph.D. work.

Xuong Nguyen-huu

Two critical things about Xuong’s background, He had worked for several years in High Energy Physics in the early 1960’s at Berkeley just before he came to UCSD and so was familiar with some of the recent instrument development in High Energy Physics 2. He knew how to write Fortran programs for the IBM 1130.

When I started work in Xuong’s lab in 1970 he had already developed the screenless precession method for analyzing film data but he was asking the question How could we build a better (electronic) detector for Protein Crystallography ?

The right pieces at the right time This was one of those lucky times in the development of technology when the important pieces of what we needed were all just becoming available. We just had to understand what they were and blend them together for a new application.

Georges Charpak and Victor Perez-Mendez We drew on pioneering work from these two people Georges Charpak and Victor Perez-Mendez

Georges Charpak had developed gas-filled wire chambers for use as position sensitive detectors in high energy physics (he later won the Nobel Prize for this) And Victor Perez-Mendez, a High Energy physicist at Berkeley, had developed an accurate position readout method for these detectors based on wire wound delay lines.

In 1972 Xuong convinced Victor Perez-Mendez to help us build a wire chamber detector for a protein crystallographic data collection system using his delay line position readout system The wire planes and delay lines were built at UC Berkeley by Victor Perez-Mendez The gas tight enclosure and detector mount were built at UC San Diego in Xuong’s lab

Concept drawing of multiwire counter with delay line readout

Wire frame used in the Mark I detector

Cross section of Mark I

An old GE quarter circle diffractometer was donated by Joe Kraut’s Lab at UC San Diego and we mounted it on the table top of a Picker sealed tube X-ray generator.

The Mark I Diffractometer at UC San Diego in 1975

Diffractometer: automatic but one spot at a time

The Mark I system covered a big piece of the diffraction pattern 50 – 100 spots

Diffraction pattern from Mark I

University of California, San Diego 1975 Ph.D. Physics University of California, San Diego 1975 Title of my Dissertation The Multiwire Proportional Counter Used as a Position Sensitive X-ray Detector for Protein Crystallography One of the important crystallographic results reported in my thesis was a good strong uranium peak in a difference Patterson map generated from data collected on the Mark I multiwire Diffractometer from Dihydrofolate Reductase (crystals grown by Dave Mathews in Joe Kraut’s lab at UCSD).

X-ray Based Structure Solution The Big Picture

But we wanted to improve the detector system some more. An obvious next step was to use a pair of detectors instead of just one to intercept more of the diffraction pattern.

We learned to build all the parts of the multiwire detectors in Xuong’s lab

We were careful to do it right.

The two-detector Mark II system started operation in Xuong’s lab in about 1982.

More solid angle, more reflections

With two detectors and the increased beam intensity of the rotating anode X-ray generator, heavily replicated data sets could be collected in 10-18 hours often from only one crystal !

This instrument in Xuong’s lab became an NIH research resource about 1983. Protein data collection time was awarded to groups who submitted proposals to use the machine.

From 1975 to 1984 I stayed on in a Research Scientist Position in Xuong’s lab at UC San Diego as we maintained and improved the Mark II multiwire diffractometer system.

But …. There was a clear demand for a commercial version of these multiwire counter detectors.

In 1983 Xuong, Chris Nielsen and I started a company called Area Detector Systems Corporation First business location: my two- bedroom apartment near UC San Diego

First workshop in my apartment in 1984

Parts of first ADSC multiwire counter system in my living room in early 1984

This detector, S/N 001, installed in David Eisenberg’s Lab at UCLA in September 1984

1985 - ADSC moved out of my apartment and into an 800 square foot space in a business park in San Diego.

We set up the equipment we needed to build multiwire counters. We built our own wire winding machine to string the fine wires on the wire planes. We bought and modified a coil winding machine so my wife Haruko could wind the delay lines that were used for the X,Y position readout. We designed and built the readout electronics (I did many of the printed circuit layouts myself on a light box with black tape).

The wire plane winding machine we built.

A wire plane on the paddle of our wire winding machine

Coil winding machine custom modified for winding the very small, #38 gauge, wire required to make the delay lines

Delay lines for the position readout

A double-protractor system UCLA late 1987 S/N 001 and S/N 016

Motor driven two theta table U Texas Austin 1988 in Marvin Hackert’s lab

Six freshly-built ADSC multiwire detectors in our shop in 1990

From 1984 to 1992 ADSC built and installed 83 multiwire detectors

Typical coverage of diffraction pattern by a pair of ADSC multiwire detectors

Ron Burns--a worthy competitor-- developed the Xentronics detector 1986 Photograph Provided by Sue Byram

Concept drawing of Xentronics detector filled with Xe / CO2 @4 atm Strong, Spherical Beryllium window

Typical solid, Xentronics detector