LOU TEMPERATURE PHYSICS AT AHHERST COLLEGE
Joel E. 6ordon
Physics Department
Amherst College
Amherst, Massachusetts 01002
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Volume V I I
Number 3
A p r i l , 198
FEATURING
EEGADS! DEPARTMENT OF ENERGY (DOE) PROVIDES FREE
LABORATORY EQUIPMENT TO UNIVERSITIES
by L.L. Barker, J. Masters, and J.D. Taylor
IMPROVING UNDERGRADUATE EDUCATION I N THE BIOLOGICAL
SCIENCES: A SYSTEMATIC APPROACH by J. E. Brenchley
LOW TEMPERATURE PHYSICS AT AMHERST COLLEGE
b y Joel E. Gordon
ADVANCING AN UNDERGRADUATE RESEARCH PROGRAM
b y Raymond J. Giguere
THE TOTAL SYNTHESIS OF NATURAL PRODUCTS AT UNDERGRADUATE INSTITUTIONS bv Thomas E. Goodwin
UNDERGRPDUATE LASER PRDJE~TSAT FORT LEWIS COLLEGE
b y R.C. E s t l e r , D.M. Mehs, and J.W. M i l l s
THE A I R FORCE OFFICE OF SCIENTIFIC RESEARCH SUMMER
RESEARCH PROGRAM by J. K l i n k and V. DelVecchio
CHANGES AND NEW DIRECTIONS I N THE RESEARCH
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CORPORATION GRANTS PROGRAM by John P. Schaefer
I THE COLLEGE SCIENCE INSTRUMENTATION PROGRAM
At4 INSIDERS VIEW by Duncan E. McBride
NATIONAL INSTITUTES OF HEALTH ACADEMIC RESEARCH
ENHANCEMENT AWARD by J e r r y R. Mohrig
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This year w i l l mark the f o r t i e t h anniversary o f
low temperature physics a t Amherst College.
The
f i r s t step toward a new research endeavor i n
Amherst's physics department was taken a year e a r l i e r when Theodore S o l l e r returned t o h i s p o s i t i o n as
a Professor o f Physics i n the sumner o f 1946 a f t e r
having spent the war years as a s t a f f member o f the
There S o l l e r had
Radiation Laboratory a t M.1.T.
worked on the development o f phosphors f o r use i n
cathode r a y tubes. Bolstered by a $4000 grant from
the Research Corporation, he hoped t o begin a r e search program a t Amherst on phosphor properties
soon a f t e r h i s return. His plans were altered, however, by the educational changes about t o be l n i t i ated a t t h e College. These changes, which came t o
be known as the "New Curriculum", had a far-reaching
impact not merely on education a t Amherst, b u t on
much o f the t h i n k i n g about l i b e r a l a r t s education i n
the United States i n the two decades which followed
World War 11.
Among the innovations of the "New Curriculum"
was a rigorous year-long course i n t h e physical s c i ences and mathematics which was t o be required o f
a l l enterinq students.
(With t h e coming o f Arnold
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Arons t o Amherst i n 1952 the course became the
famous Science 1-2, a combined physics-calculus
course which Amherst freshmen loved t o hate while
e n r o l l e d and about which they bragged endlessly once
having graduated). I n 1946-47 S o l l e r was deeply i n volved i n the planning of t h i s course and i n h i r i n g
new f a c u l t y members t o help s t a f f i t . Two young
p h y s i c i s t s from Yale, William Fairbank and Bruce
Benson, were hired, and came t o Amherst i n the f a l l
of 1947. Fairbank was a low temperature physicist,
w h i l e Benson was i n nuclear physics.
They, l i k e
S o l l e r , f u l l y intended t o c a r r y on research, as w e l l
as teach, a t Amherst.
It was evident t o a l l three
t h a t a cooperative research program i n a s i n g l e area
of physics made more sense than three separate research endeavors. They soon agreed t h a t low tempera t u r e physics was a research area i n which Amherst
c o u l d hope t o compete, f o r a t t h a t time there were
few academic i n s t i t u t i o n s i n the country other than
Yale, M.I.T.,
and Berkeley t h a t had a helium l i q u e fier.
They reasoned t h a t i f they could b u i l d a
l i q u e f i e r a t Amherst, they could e s t a b l i s h an ongoing low temperature research program o f some significance.
They went t o Sam C o l l i n s o f M.I.T.
for
advice. Collins, who had engineered a. new type o f
h e l i u n ~l i q u e f i e r (versions o f which were l a t e r produced comnercially by Arthur D. L i t t l e . Inc.),
generously supplied f a r more than advice; he prov i d e d drawings o f h i s l i q u e f i e r design as well as
forms and machines f o r winding heat exchange c o i l s .
Thus armed the Amherst t r i o went t o New York
and persuaded the Research Corporation t o augment
S o l l e r ' s o r i g i n a l $4,000 grant w i t h an a d d i t i o n a l
$6.000.
This $10.000 was t o be used t o b u i l d the
l i q u e f i e r as w e l l as t o i n i t i a t e a research program
i n t o the properties o f the r a r e isotope o f helium,
He-3.
S o l l e r learned some years l a t e r from a s t a f f
member of the Research Corporation t h a t the Corporat i o n made the a d d i t i o n a l grant because i t wished t o
encourage research a t a small college, but that, i n
f a c t , there was l i t t l e confidence t h a t a successful
l i q u e f i e r could a c t u a l l y be b u i l t a t Amherst.
This pessimism proved t o be ill-founded,
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though almost f o u r years were required t o complete
the l i q u e f i e r . The machine was t o be b a s i c a l l y a
C o l l i n s l i q u e f i e r , but i t would incorporate one
unique feature; i t would have a chamber i n which
helium mixtures much-enriched i n He-3 could be obtained by u t i l i z i n g a "heat-flush. "technique which
had been developed by C.T. Lane and Henry Fairbank
i n 1948. This technique makes use o f the f a c t t h a t
when there i s a temperature gradient i n a tube of
l i q u i d helium which i s a t a temperature below 2.2OK.
the so-called s u p e r f l u i d atoms o f He-4 w i 11 migrate
toward the warmer end while the He-3 atoms, along
w i t h the normal He-4 atoms, w i l l be "flushed" toward
the cooler end. This He-3-enriched mixture can then
be pumped o f f and analyzed. Once the l i q u e f i e r was
b u i l t , the Amherst group intended t o use i t f o r the
production o f mixtures as h i g h l y enriched i n He-3 as
possible.
For the most p a r t S o l l e r and Fairbank concent r a t e d on b u i l d i n g the l i q u e f i e r , while Benson began
construction o f a mass spectrometer which would be
used t o measure the abundance r a t i o i n the He-3He-4 mixtures produced w i t h the heat f l u s h apparatus. By 1952 the group had a working l i q u e f i e r and
had produced some He-3-enriched
gas.
Several
events, however, now brought about a r e d i r e c t i o n o f
the Amherst research e f f o r t .
Fairbank accepted a
p o s i t i o n a t Duke. He was replaced by James Nicol,
who was more interested i n the properties o f superI t was also
conductors than i n those o f helium.
learned t h a t He-3 was t o be made a v a i l a b l e f o r r e search purposes by the Atomic Energy commission.
(By 1952 t r i t i u m was being produced a t Oak Ridge i n
sizeable quantities.
This r a d i o a c t i v e isotope o f
hydro en decays w i t h a 12.3 year h a l f - l i f e i n t o
He-3.7 Thus Amherst's modest e f f o r t t o produce He-3
was now superfluous.
Nicol and S o l l e r and t h e i r
honors students began a study o f superconductivity.
Benson, a t the suggestion o f Arnold Arons, s h i f t e d
h i s a t t e n t i o n t o oceanographic applications o f mass
spectrometry.
During the middle 1950's the low temperature
group b u i l t several cryostats for i n v e s t i g a t i n g the
'thermal and magnetic properties o f superconductors
as w e l l as an adiabatic demagnetization apparatus
f o r making measurements below 1°K. However, perhaps
t h e most important work which came out o f Amherst's
l o w temperature l a b during t h i s period was the d i s covery by N i c o l and S o l l e r t h a t c e r t a i n carbon
r e s i s t o r s manufactured by the Speer Corporation had
very stable, and reasonably simple, low temperature
resistance-temperature c h a r a c t e r i s t i c s . For a l l but
t h e most precise thermometry, these r e s i s t o r s could
be c a l i b r a t e d between 4 and 1.5"K and the c a l i b r a on could then be extrapolated f o r determining
For many exabsolute temperatures below 1.5"K.
p e r i m e n t a l i s t s t h e Speer r e s i s t o r became, and has
remained, a simple and r e l i a b l e thermometer f o r use
i n the temperature region 0.08 and 1.5"K.
Nicol l e f t Amherst f o r A.D. L i t t l e i n 1957. I n
t h a t same year Colby (Skip) Dempesy and Joel Gordon
arrived, and t h e research focus o f the low temperat u r e group s h i f t e d once again. A t the suggestion o f
Nicholas K u r t i o f Oxford. Dempesy, Gordon, and
Sol l e r turned t h e i r a t t e n t i o n t o t h e magnetic hyperf i n e (nuclear) c o n t r i b u t i o n o f the s p e c i f i c heat o f
r a r e e a r t h metals. Almost simultaneous'ly w i t h O l l i
Lounasmaa o f Argonne they reported a c a l o r i m e t r i c
determination of the hyperfine i n t e r a c t i o n constant
f o r holmium which agreed exceedingly well w i t h the
value predicted by Bleaney on the basis o f paramagn e t i c resonance measurements. Dempesy. Gordon, and
S o l l e r a l s o b u i l t a c r y o s t a t f o r use between 4 and
20°K i n order t o i n v e s t i g a t e the magnetic contribut i o n t o t h e specific heat o f r a r e e a r t h metals i n
t h i s temperature region.
I n 1958-59 another h h e r s t p h y s i c i s t , Robert
Romer, spent the year a t Duke working w i t h R i l l
Fairbank, who had been h i s senior t h e s i s advisor a t
Amherst.
A t Duke Romer investigated nuclear spin
r e l a x a t i o n i n He-3.
Upon r e t u r n i n g t o Amherst he
measured t h e nuclear s u s c e p t i b i l i t y o f He-3 and a l s o
began an i n v e s t i g a t i o n o f the s u p e r f l u i d properties
of He-4.
I n 1963 Romer joined Dempesy and Gordon
i n an attempt t o observe a possible nuclear c o n t r i b u t i o n t o the s p e c i f i c heat of U-235. The experi-
mental worki c a r r i e d out a t Brookhaven i n the sumner
o f 1963. made use o f the r e l a x a t i o n ( o r t r a n s i e n t )
method o f measuring s p e c i f i c heats. I n t h i s method
one d e l i b e r a t e l y connects a sample
to i t s
environment through a weak thermal l i n k ( i n s t e a d of
seeking thermal i s o l a t i o n as i s done i n the more
conventional heat capacity measurement) and measures
t h e s p e c i f i c heat by observing the t r a n s i e n t temperature response o f t h e sample t o step changes i n t h e
heat i n p u t t o the sample.
Because o f the thermal
l i n k . a sample w i t h r a d i o a c t i v e self-heating (such
as U-235) can be measured a t temperatures below 1°K.
a temperature v i r t u a l l y inaccessible i f the sample
i s thermally isolated. This same method was used by
Gordon and collaborators a t Harwell. England several
years l a t e r t o measure the low temperature s p e c i f i c
heats o f neptunium and plutonium. The measurements
o f Dempesy, Gordon, and Romer on U-235 were the
f i r s t evidence o f a hyperfine c o n t r i b u t i o n t o the
s p e c i f i c heat o f an a c t i n i d e metal. As a check on
t h e measu.rements, the three a l s o looked a t the spec i f i c heat o f U-238 and confirmed t h a t t h l s material
d i d n o t undergo a bulk superconducting t r a n s i t i o n
above D.Z°K.
During the remainder o f the 1960's t h e low
temperature group a t Amherst concentrated on t h e
e f f e c t s o f pressure on normal f l u i d d e n s i t i e s i n
helium below 2.Z°K ( t h i s work was c a r r i e d o u t by
Romer and a new colleague. Richard Duffy) and on
t h e thermal and magnetic properties o f uranium and
uranium compounds.
A He-3 c r y o s t a t was b u i l t .
thereby making i t easier t o c a r r y out experiments
between 0.3 and 1.2"K ( t h e lowest temperature which
can be e a s i l y obtained by pumping on a b a t h o f
He-4).
Another piece o f apparatus which expanded
t h e c a p a b i l i t i e s o f the l a b was designed and b u i l t
i n 1963 by an honors student. This was a superconducting solenoid which could produce h i g h l y uniform
magnetic f i e l d s o f up t o one t e s l a over a c y l i n d r i c a l v o l u m e o f 4 cm. i n diameter and 12 cm. i n
length. This magnet i s a f i n e example o f the many
instances i n which Amherst students contributed to.
as well as learned from, the on-going low temperat u r e research program.
Throughout the nearly twenty years between t h e
e a r l y 1950's and t h e end o f the 1960's the helium
l i q u e f i e r b u i l t by S o l l e r , Fairbank, and Benson produced l i q u i d helium a t a r a t e o f f o u r l i t e r s an
hour. The machine, l i k e a high-strung thoroughbred.
o f t e n r e q u i r e d t i g h t supervision and more than a
l i t t l e coaxing, b u t produce i t did, f a r more r e l i ably. i n fact, than the small comnercial l i q u e f i e r
which replaced i t when the physics department moved
t o a new b u i l d i n g i n 1969.
Curiously enough, although t h e 1969 move from
Fayerweather H a l l t o the new M e r r i 11 Science Center
provided t h e low temp l a b (as w e l l as the r e s t of
t h e department) w i t h much improved f a c i l i t i e s , i t
coincided w i t h a retrenchment i n the cryogenics program. By the beginning o f the 1970's S o l l e r had ret i r e d and both Romer's and Demesy's research i n t e r e s t s had s h i f t e d away from low temperature physics.
Gordon continued h i s work on the low temperature
p r o p e r t i e s of t h e actinides, a1though there was an
i n t e r l u d e of several years i n which he studied the
p r o p e r t i e s o f f e r r o e l e c t r i c m a t e r i a l s near t h e i r
phase t r a n s i t i o n . By the end o f the 1970's he had
begun a c o l l a b o r a t i v e e f f o r t w i t h a group from the
Centre dlEtudes Nucleaire i n Grenoble on the thermal
and magnetic p r o p e r t i e s of the NaCl s t r u c t u r e a c t i nide compounds.
A new low temperature p h y s i c i s t ,
Selden Crary, j o i n e d the Amherst f a c u l t y i n 1978.
His i n t e r e s t l a y p r i m a r i l y i n studying t h e propert i e s o f helium f i l m s on graphite. I n January, 1980.
Louis Bloomfleld, who had done h i s honors work w i t h
Crary, received the f i r s t Apker award f o r outstandi n g achievement by an undergraduate for h i s research
on t h e onset of s u p e r f l u i d i t y i n unsaturated he1 ium
f i l m s on graphite.
The 1980's brought a number o f changes. Easy
access t o l i q u i d helium was now assured. f o r the
f i v e colleges i n the Pioneer Valley (Amherst,
Hampshire. M t . Holyoke, Smith, and the U n i v e r s i t y o f
Massachusetts) received a matching grant from t h e
National Science Foundation for the purchase o f a
large helium l i q u e f i e r .
This grant was obtained
l a r g e l y through the e f f o r t s of Robert Hallock who
has established a t h r i v i n g research program i n low
temperature physics a t the U n i v e r s i t y o f Massachus e t t s . Meanwhile a new research area, l a s e r spectroscopy, r a p i d l y came t o replace cryogenics as the
p r i n c i p a l research a c t i v i t y a t Amherst. By 1986 the
l a s e r spectroscopy group contained three f a c u l t y
members, A r t h u r Zajonc. L a r r y Hunter. and Rohert
Hilborn, as w e l l as research associate Daniel
Krause.
Nonetheless the work i n low temperatures
continues. Almost e x a c t l y f o r t y years from the time
Ted S o l l e r received the f i r s t grant from The
Research Corporation, the College received an Exxon
Education Foundation Grant from the Research Corpora t i o n t o support Gordon's work on the s p e c i f i c heat
o f a c t i n i d e compounds,
I n the years between these two Research Corpora t i o n grants, the low temperature research group a t
Amherst received generous support from the O f f i c e o f
Naval Research, from the National Science Foundation, and from the Trustees o f Amherst College. The
research would n o t have been possible without t h a t
support, b u t n e i t h e r would i t have been possible
without the advice and assistance o f two superb
machinists. George Smith, who came w i t h S o l l e r t o
Amherst from M.I.T.
i n 1946. and Don Martin. who
came twenty years l a t e r .
More recently, as e l e c t r o n i c s and computer i n t e r f a c i n g have come t o play
an i n c r e a s i n g l y important r o l e i n research, the
assistance o f Amherst's e l e c t r o n i c s technician P h i l 1
Grant, has a l s o been v i t a l .
Yet most important o f a l l t o the success o f low
temperature physics a t Amherst have been t h e students. A t Amherst, as a t s i m i l a r undergraduate i n s t i t u t i o n s , research i s an i n t r i n s i c p a r t of the
educational enterprise.
P a r t i c i p a t i o n i n the low
temperature research program has given many Amherst
students t h e i r f i r s t research experience, but those
students have c o n t r i b u t e d much i n r e t u r n . Without
t h e i r i n t e l l i g e n c e , t h e i r eagerness, t h e i r i n s i g h t s .
and t h e i r capacity f o r hard work Amherst's low temperature research program would have accomplished
very l i t t l e . Many o f those students continued on i n
physics and, i n a s i g n i f i c a n t number o f cases, i n
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d i d research w i t h one o r another o f the f a c u l t y members i n the low temperature group are now on the
f a c u l t y o f such colleges as Carleton,-Kalamazoo,
Kenyon. Lafayette, and Oberlin, and o f such univers i t i e s as Cal Tech, C a l i f o r n i a (Riverside and San
Diego), Michigan State, Pittsburgh, and Virginia.
Other alumni o f the Amherst low temperature l a b are
now lawyers, doctors, engineers, and businessmen.
One i s an inventor and another a professor o f comp a r a t i v e l i t e r a t u r e a t the University o f Amsterdam.
Yet whatever t h e i r present occupation, a l l o f them,
so f a r as I know, regard t h e i r undergraduate research experience as having been an i n t r i n s i c and
important p a r t o f t h e i r l i b e r a l a r t s education.
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I n closing. I should l i k e t o thank Ted S o l l e r
and Bruce Benson. They have answered my many quest i o n s concerning the e a r l y h i s t o r y o f low temperat u r e physics a t Amherst. More Importantly, over the
years they have taught t h e i r colleagues and countl e s s students a good deal about physics, about experimental technique, and, above a l l , about the
importance o f patience and o f consideration f o r
I should a l s o l i k e t o thank the Exxon Eduothers.
c a t i o n Foundation and the Research Corporation f o r
t h e i r support.
CORRECTION: I n the January Newsletter the contribut i o n "The Development o f Optical Physics a t Rhodes
College" was l i s t e d under the authorship of Joel H.
Taylor. This, as many o f you know. i s incorrect,
and the author i s Jack H. Taylor. This a r t i c l e w i l l
be r e p r i n t e d i n the news magazine o f the Optical
Society o f America, 0 t i c s News, t o f o l l o w a series
o f l e c t u r e demonstrat ons on r a d i a t i o n exchange by
J.H. Taylor t h a t has appeared i n t h i s monthly magaz i n e since the January issue.
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