This issue is dedicatedto the memory ofJohn Wheatley

Inside This IssueI t is appropriate that this issue, de-

voted to frontier topics in science,technology, and technology transfer,

be dedicated to the memory of JohnWheatley, one of the great scientists andtechnologists of the twentieth century. Hisuntimely death at age fifty-nine occurredbefore he and his Los Alamos col-laborators, Greg Swift and Al Migliori,had completed the article on natural heatengines that appears in this issue. Naturalengines are a departure from traditionalheat engines in that their design capitalizeson irreversible processes instead of tryingto minimize them. These are engines withno moving parts whose simplicity and re-liability make them ideal for applicationsin space. John loved them because theycould be understood on the basis ofclassical thermodynamics and their designtook full advantage of nature’s way ofdoing things. He lived to see the successfuloperation of the liquid sodium acousticengine and would have been enormouslypleased that the article on his pet projectincludes some good solid data on thisparticular natural engine.

Our experience with John bore out hisreputation for meticulous care, soundpedagogy, and stubbornness in doingthings the “right” way-which meant hisway. Although enthusiastic about the in-itial draft written by our staff writer RogerEckhardt (with help from Greg and Al),John, as predicted, chose to spend an en-tire week rewriting the manuscript so thatit would contain the “right” approach tounderstanding the thermodynamic princi-ples underlying the operation of naturalengines. We are honored to be publishingthis superb and easily accessible article.

John Wheatley was an important pres-ence wherever he went, and his passingwas a shock to all who knew him. Toprovide our readers with a glimpse of Johnand his numerous contributions to low-temperature physics, we organized around table, shortly after his death, amongthose of his close collaborators who werethen at Los Alamos. The title of the dis-cussion, “Pushing The Limits,” sums up

John’s approach to everything he did atwork and at play. We hope the portraitthat emerges will convey at least in partthe impact of this inspired and inspiringman.

One of John’s great contributions totechnology was to push the low-tempera-ture frontier down to a few thousandths ofa degree above absolute zero. Another im-portant technological frontier is definedby the shortest time scale on which eventscan be measured and controlled. An articleby Bob Hammond, entitled “Photocon-ductivity and Picosecond Signals,” de-scribes the breakthrough being madewith photoconductors in generating andmeasuring electronic signals on pico-second time scales and in tracking time-varying radiation with picosecond ac-curacy. The picosecond rise and fall timesof photoconductivity were not known un-til photoconductors could be stimulatedby ultrashort laser pulses. The rapidresponse of photoconductors is being ex-ploited by the Electronics Division at LosAlamos in ultrafast power switches forgenerating accurately timed, short-rise-time, high-power electrical pulses and inultrafast radiation detectors that can fol-low the rapidly varying signals from laserfusion experiments and nuclear weaponstests. Perhaps the most exciting newphotoconductive device is one that canmeasure the performance of tiny segmentsof integrated circuits. Such a deviceenabled Bob Hammond and his colleaguesto observe for the first time the picosecondphenomenon of carrier-velocity overshootthat had been predicted by theory. Thisphenomenon may provide a basis for evenfaster integrated circuits.

Frontiers defined by cultures providedalmost as much of an adventure to JohnWheatley as those defined by technology.He took his low-temperature work to thefar reaches of Argentina and to the scien-tific community of Finland and made histechnological innovations availableworldwide through his founding of theSHE Corporation. In this issue we reporton another type of adventure in tech-

nology transfer, this time in the CaribbeanBasin and with economic rather thanscientific goals in mind. Los Alamos is acenter of research in geothermal energyand in energy resources planning and de-velopment. The Caribbean Basin projectis designed to transfer that expertise tocountries in Central America and theCaribbean Islands whose economic dif-ficulties might be alleviated by the devel-opment of indigenous energy resources.Bob Hanold and Verne Loose, leaders ofthis unusual project, along with aboutthirty-five geologists, geochemists,geophysicists, and economists, have beentraveling back and forth between the Lab-oratory and the Caribbean Basin. They areworking with local professionals toevaluate economic and energy needs andto explore and develop the most promis-ing natural resources. AccompanyingBob’s and Verne’s overview of this prece-dent-setting project are a series of shortpieces that describe the technical workbeing accomplished by Los Alamos scien-tists in the jungles and cities of CentralAmerica.

This issue closes with a reminiscence byHerb Anderson in honor of Nick Metrop-olis on his sixtieth birthday. It concernsthe early days of one of the most impor-tant frontiers of our time. the frontier ofelectonic computing. Herb’s wonderfulstories of Nick’s innovative work on theMANIAC with his many illustrious col-laborators is somehow a fitting end to anissue dedicated to the memory of JohnWheatley. ■

EditorNecia Grant Cooper

Art DirectorGloria Sharp

Science WritersRoger Eckhardt

Nancy Shera

Assistant EditorDixie McDonald

Contributing EditorHollie Sowerwine

Design and IllustrationKatherine Norskog

IllustrationJim Cruz, Jeff Segler

Ward Zaelke

PhotographyJohn Flower

Photo Laboratory WorkErnesto Archuleta, Gary Desharnais

Debbie Fisher, Chris LindbergKen Lujan, Bryan O’Hare

Mike O’Keefe, Cordy R. RoybalRoger Volz, Gary Warren

PhototypesettingChris West

Dolly Lucero, Joyce MartinezKathy Valdez,

CirculationDixie McDonald

PrintingJim E. Lovato

Guadalupe Archuleta

Los Alamos Science is published by LosAlamos National Laboratory, an EqualOpportunity Employer operated by theUniversity of California for the UnitedStates Department of Energy under con-tract W-7405-ENG-36.

Address Mail toLos Alamos Science

Mail Stop M708Los Alamos National LaboratoryLos Alamos, New Mexico 87545

RESEARCH AND REVIEW

The Natural Heat Engineby John C. Wheatley, Gregory W. Swift, and Albert Migliori 2

Sidebars: The Fridge 5

The Short Stack14

The Liquid Propylene Engine 30

John Wheatley (1927-1986)

Pushing the Limits

A round table with Gordon Baym, Al Clogston, Sig Hecker,Matti Krusius, Al Migliori, David Pines, and Greg Swift

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Photoconductivity and Picosecond Signalsby Robert B. Hammond 48

Sidebar: The World’s Fastest Laser Oscillator 59

NEW INITIATIVES

Caribbean Basin ProyectoAn interview with Robert J. Hanold and Verne W. Loose 66

Sidebars: Energy Supply and Demand in Central Americaby-Linda -K.Trocki and Steven R. Booth

72The Costa Rican Peat Project

by Gary R. Thayer, K. D. Williamson, Jr., and Arthur D. Cohen 77

Geology of Honduran Geothermal Sitesby Dean B. Eppler 86

Geochemistry at Honduran Geothermal Sitesby Fraser Goff, C. O. Grigsby, Lisa A. Shevenell, andJ. Wilfred Gutierrez 90

High-Temperature Borehole Measurements at Miravalles,Costa Rica

by Bert R. Dennis and Robert J. Hanold94

HISTORY AND PEOPLE

Metropolis, Monte Carlo, and the MANIACby Herbert L. Anderson 9 6

Cover photo by John Flower. Stainless steel plates used in a liquid-to-liquid heat exchanger forthe liquid propylene Stirling engine, one of several novel heat engines studied at Los Alamos.

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