DISSERTATION By

Home , Isotopes of nickel

CYCLOTRON BOMBARDMENTS WITH HE3 a n d r 3

DISSERTATION

Presented in Partial Fulfillment of the Requirements

for the Degree Doctor of Philisophy in the

Graduate School of The Ohio State

University

Thomas William Donaven, 3.S., M.A

The Ohio State University

1952

Approved by

Adviser ( fe/\J TABLE OF CONTENTS

Cyclotron Bombardments with He^ or H3

Acknowledgements Page

Introduction 1

Description of Apparatus 3

Method of Operation 13

Purification of He^ or 17

Results 20

Conclusions 30

References 32

Miscellaneous Photographs 36

Autobiography 1*0

i 918254 Acknowledgements

It is with deep appreciation that I extend thanks to Professor

M. L. Pool for his guidance in this work. Special thanks is also due to Dr. D. N. Kundu for his advice, help, and cooperation in this project. Acknowledgement is also made to Mr. Paul Weiler and Mr.

Donald Moore of the cyclotron staff, and to the machine shop under

Mr. Carl McWhirt, for their aid in completing this work. The support given me through fellowships by The Ohio State University Physics

Department and by the Oak Ridge Institute of Nuclear Studies is gratefully acknowledged.

ii INTRODUCTION

The naturally occurring elements whose atoms are heavier than

Bismuth, i.e. Po, At, Rn, Fr, Th, Pa, U, etc. are all radioactive.

The remainder of the elements may be made radioactive by hitting them with high speed nuclei of other elements. The elements whose nuclei are normally used to create radioactivity are hydrogen and helium.

In order to give a nucleus a high speed with the minimum of equipment, it is necessary to strip all of the electrons from the atom, leaving its bare nucleus to be accelerated. It becomes increasingly difficult

to strip a nucleus as the number of electrons surrounding it increases.

Hence hydrogen, with one electron, and helium, with two electrons, are normally used to bombard other elements. The neutron, with no charge, is also used to produce radioactivity; it is effective at any speed and is derived from nuclear reactions.

Protons give reactions such as (p, n), (p, 2n), (p, ci ), and

(p, He^). These are produced by the proton entering the nucleus that it hits, becoming part of it, and then this "compound nucleus'" emits

one or more particles. The hydrogen isotope of mass two, the deuteron, gives similar reactions. However, in some cases instead of the deuteron and the bombarded nucleus forming a "compound nucleus",

the deuteron is polarized.

Thereby, the neutron or proton part of the deuteron touches the nuclear surface and then sticks to the target nucleus; the remaining part of the deuteron is left behind. This left out part is afterwards

observed as a repelled proton or outcoming neutron from the nuclear

event.

The ci particle has also been used to cause nuclear reactions of

the types (cx, n), ( c(, p), (o{ , 2n), etc. It would, therefore, be

/• -2- interesting to see what type of nuclear reactions occur for the bom barding particles of intermediate mass, i.e., the heaviest isotope,

H-3, of hydrogen, consisting of a proton and two neutrons, and for the lightest isotope of helium, He3, consisting of two protons and a neutron. One would also expect to be able to produce new radioactive isotopes of various elements since the reaction (h3} p) would seem to be a feasible method of introducing two neutrons into a nucleus and the reaction (He3, n) is equivalent to (He^ 2n). The (He^, 2n) reaction requires comparatively high energy particles, while the

(He3, n) reaction should occur at low energies* DESCRIPTION OF APPARATUS

The design of a workable system of circulating the few available cubic centimeter s of He3 and h3 was one of the main problems of this investigation. As is the case so many times, once suitable equipment is at hand the remaining problems are comparatively easy to solve.

The equipment described here works as well as could be reasonably expected and at present there are only very minor changes in it being considered. These changes will be described later.

There are at present only a few cubic centimeters of He3 or H3 gas available for cyclotron bombardments here at The Ohio State

University. This is the maximum amount of He3 or h3 that the Atomic

Energy Commission will allow anyone institution to have at one time.

Hence if cyclotron bombardments are to be made, they must be made with not more than this amount. Ordinarily about 200 cubic centimeters per hour of gas are used in making a bombardment with protons, deuterons or alphas. In an ordinary run the gas is pumped through the cyclotron tank by two eight inch oil diffusion pumps and then out into the air by a Hyper Vac 100 mechanical pump that backs up the oil diffusion pumps. Thus it is obvious that in a He3 or H3 bombardment that the

He3 or h 3 gas must be reinserted into the cyclotron after it has been

pumped out. It would also be desirable to free it from the air which

has leaked into the cyclotron and diluted the He3 or H3. There is also a certain amount of hydrogen which outgasses from the metal in

the cyclotron tank. The circulation system now to be described is

of course the last of a series of systems tried; the others did not work satisfactorily. -k-

The main requirements of a successful circulation system are the

followings it must be able to produce a vacuum of at least 10“3

millimeters of mercury in the cyclotron tank; it must return the gas

to the cyclotron tank as fast as it is pumped out; and it must have a

control to regulate the rate at which the He3 or h3 is returned to

the cyclotron tank so that the pressure may be regulated to produce

as large a beam of He3 or h3 particles as possible*

The circulation system consists of one of the regular eight inch

oil diffusion pumps backed by two DPI mercury diffusion pumps of 20

liters per second pumping speed each. The output of the mercury diffusion pumps goes to a ballast tank of about 30 liters capacity,

thence through a one and a quarter inch copper tube to the control valves and from there directly back into the cyclotron. Figure 1

shows a diagram of the system. There is a liquid air trap between

the mercury diffusion pumps and the oil diffusion pumps and also one between the ballast tank and the control valves. There is also a liquid hydrogen trap which sits on the top of an unused oil diffusion

pump.

Mercury diffusion pumps are used to back up the oil diffusion

pump since they can operate with a backing pressure as high as 10 millimeters of mercury. This pressure 'would require the presence of almost 500 cubic centimeters of gas in the circulation system. It would require only about 50 - ?5 cubic centimeters of gas to dilute

the 2 cubic centimeters of He3 or H3 used in a bombardment to the point where the beam of He3 or H3 particles would be so weak that it would be useless to continue the bombardment. Thus, there is a large reserve capacity available to insure that the mercury pumps will not

stop operating because of too high a backing pressure. If they were -5-

CIRCULATION SYSTEM FOR He & H’

D iffu sio n

Pumfr IX' Cyclotron

Tank

Figure 1 -6-

to stop operating because of too high a backing pressure, the mercury

in them would probably be distributed through-out the system. If

they are operating and connected to the cyclotron without liquid air

in the traps, it takes only a few seconds for enough mercury to diffuse into the cyclotron to make its operation impossible because of the high

vapor pressure of mercury. Even with liquid air in the traps, great

care must also be taken to insure that the pressure in the mercury

pumps is lower than that in the cyclotron before the valve between

them is opened3 otherwise the rush of gas from the mercury system to

the cyclotron carries mercury vapor past the trap and into the cyclotron.

The line between the oil diffusion pump and the mercury pumps consists

of two parts. The first is a three inch line which leads through a valve to the mechanical pump used on regular runs and the second part consists of a two inch valve and a large three inch diameter liquid air trap.

It is necessary that the line between the oil diffusion pump and the mercury pumps be of fairly large diameter and unobstructed;

otherwise the mercury pumps will not Ixave enough pumping speed to back

the oil diffusion pumps. During a He3 or H3 bombardment the valve in the three inch line to the mechanical pump is closed and the two inch valve to the mercury diffusion pumps is opened.

The two inch valve between the cyclotron and the mercury diffusion pumps deserves special mention because of its excellent operating characteristics. Ordinary valves, such as those used between the oil diffusion pumps of the cyclotron and the Hyper Vac 100 mechanical pump which produced their backing pressure, frequently leak air into -7-

the system around, the stem when they are being opened or closed, or

even when they are stationary, either open or closed. The ordinary valves are made vacuum tight by packing high vacuum wax around the

stem. However, this makeshift procedure does not prevent the valves

from leaking while they are being opened or closed, which is the time

that they most frequently leak. The two inch valve mentioned above, however, has not been found to leak at any time. Besides the regular

seat and seal it also has a seat and seal which seals the stem off when the valve is completely open. The packing around the stem is also designed so that the motion of opening and closing the valve does not introduce any air into the system. Special thanks must be extended to Mr. Carl McWhirt, Director of the Physics Machine Shop

for making this valve.

From the output of the mercury diffusion pumps there is a one-

half inch line that leads to the 30 liter ballast tank which is

steadied by several heavy lead blocks. This tank stores the He-3

or H3 gas, air, and hydrogen which are the three gases in the system.

It also serves to smooth out the flow of gas during circulation and make it smooth and even. Some earlier circulation systems with no ballast tank gave a very uneven gas flow. The circulation system described here gives a very even flow which may be due either to

the nature of the system or perhaps to this large ballast tank that acts in a manner analogous to a condenser in an electric power supply

filter. The system has never been operated without it so its exact effect is unknown. Since the system operates satisfactorily in its present condition there are no plans to change the ballast tank arrangement. -8-

From the ballast tank a one-half inch copper tube leads to aG one G and one-fourth inch pipe, which in turn leads to the control valves.

« ® ' c The one-half inch tube is necessary to allow certain berais and con volutions to be made which are necessitated by the geometry of the

cyclotron and the associated circulation system. The one and one- ®

fourth inch line is necessary to allow the gas, once it has been pumped from the cyclotron and into the ballast tank, to return to

the gas flow control valves and thence into the cyclotron as fast as,,

the oil diffusion pump pumps it out of the cyclotron. Earlier, a

one-half inch line had lead from the ballast tank to .the control valves, but it was found that the gas could not be returned to the cyclotron

tank fast enough to keep the proper operating pressure in the cyclotron

tank. Near the point where the one-half inch tube and the one and

one-fourth inchpLpe join, there is a "pump out* through a one-

eighth inch Hoke valve. This "pump out" serves to evacuate the

circulation system by means of a mechanical pump and also is the means by which the He3 or Il3 gas is introduced into the circulation system.

On the other end of the one and one-fourth inch pipe are the two

control valves that regulate the rate at which the gas circulates.

The two valves are in parallel; one of them is a standard one inch valve for controlling water flow while the other is a one-eighth inch Hoke vacuum valve. Both of them leak around the stem at times.

The one inch valve is of course the worst offender in this respect because of its design for water control only, but in geperal both are o satisfactory. o There are several solder joints in the above system of piping and valves so it would not be amiss to say a word about them. It „ g * e o has been 'found that soft solder joints almost invariably leak, especially if they are subjected to strain or vibration. A« satisfactory

<5' o joint can be made by 3ilver soldering the joint and then, while a , vacuum is inside the joint, covering it with soft solder. This type of joint has beep very satisfactory both as to strength.and vacuum tightness. Such joints have been tested on a helium leak detector and found to be tight in every instance. A great help in achieving strong, vacuum-tight silver-solder joints is the practice of machining, with a clean oilless tool, the surfaces to be silver soldered immediate ly before the silver-soldering operation. Such joints are often vacuum tight even without a covering of soft solder. This practice, is especially helpful in silver soldering stainless steel which other wise has' a coating that often successfully resists the usual silver soldering flux.

There is also a trap in the system which contains -liquid hydrogen during a bombardment using He3 or h 3. -The purpose of this trap is to freeze out the air that has leaked into the cyclotron and circulation system. This hydrogen trap sits on the top of the oil diffusion pump which is not turned on during an He3 bombardment. During a ’twelve hour bombardment about twenty five liters of liquid hydrogen are used to cool the trap. The vapors from the evaporating liquid hydrogen are conducted through a one inch® hose to an exhaust fan which blows a them outside the building. Were the vapors allowed to accumulate there could well be a serious explosion in the cyclotron building.

O However, as the hydrogen gas is so much lighter than air, the vapors upon evaporation immediately rise to the top of £he room where they are exhausted to the outside of the building. As additional precautions the doors to the cyclotron room were left open and smoking was pro hibited. Every attempt was also made to remove any spark producing machinery from the room.

The hydrogen trap is not entirely successful in freezing out all of the air that leaks into the cyclotron and circulation system. That it does freeze out part of the air has been determined by putting liquid hydrogen in the trap, introducing air into the cyclotron and then collecting the several cubic centimeters of gas -which is pumped out of the cyclotron immediately after the last of the liquid hydrogen has evaporated. As the last of the liquid hydrogen evaporates, it has been further noticed that the vacuum in the cyclotron becomes very poor. These two events are considered indications that the liquid hydrogen trap freezes out at least part of the air that leaks into the cyclotron and circulation system during an He3 or H3 bombardment.

It is possible that the efficiency of the trap could be improved by putting fins on the vacuum side of the trap. This would greatly increase the area available for the air to freeze out on.

From the fast rate at which the intensity of the He3 or H3 beam falls off immediately after a bombardment is started with 2 cubic centimeters of He3 or h3} it seems reasonable that the liquid hydrogen trap does not freeze out all of the air that leaks in. Within about five minutes after 2 cubic centimeters of He3 or h3 is introduced into the system, the beam intensity falls by a factor of two to four, and since only about 2$ cubic centimeters of hydrogen is outgassed from the cyclotron during a twelve hour run, it seems reasonable that -li

the beam intensity falls due to dilution of the He3 or h3 b y air.

That the He3 or H3 is diluted instead of being absorbed is shown by

the fact that the circulation-controlling valves must be closed down

considerably in the first few minutes of the He3 or h3 bombardment.

Probably there is a certain equilibrium value of air pressure -vihich happens to fall in the range in which we are interested.

The He3 or H3 is inserted into the system as was mentioned pre viously, through a "pump out" in the circulation system. T h e Re3

gas comes in a glass capsule and is diluted with about $0% o f other

gases, at least part of which is h3« The presence of h3 is natural

since the radioactive decay of h3 is the source of He3,. The percentage

of H3 present is unknown, but it is sufficient to make the glass

capsule radioactive with h3. The inside surface of approximately

one square centimeter of the glass when read in a windowless counter

of about 50% geometry gave about 2000 counts per second. There is

also enough h3 present so that all samples bombarded with H e 3 gave

from 10 to 2000 counts per second of H3 activity. The glass capsule

is inserted into a soft copper tube and held in the center o f the tube by rolls of wire screening. One end of the wire is soldered, shut while the other end has an outlet for connecting it to the circulation

system. The tube is loaded with the He3 or h3 capsule, evacuated,

connected to the circulation system and then crushed at the proper '

time with an ordinary G clamp. This method has the virtues of simplicity and certainty, since the capsule can be heard to break. A n earlier ' method of using a rod actuated through a sylphon to break a capillary

seal had, upon one occasion, failed to break iihe capsule a n d „free the He3 gas. The sylphon solder joint was also very difficult |

- • In order to 6ontras.t\the .two methods of running the cyclotron during

a regular non and during a' bombardment in which the. circulation1system is

used, a short and. necessarily incomplete, description-of the two methods

will be given. It would not be feasible to give detailed instructions on

how to operate either the -cyclotron or the circulation system; such . ■

instructions would furthermore1 be out of place here. The many operations

.and checks involved in the. simple.phrase "turn.on the cyclotron" would ■

■require several pages of.description-and wouid not mean much to1 anyone

not intimately familiar with the cyclotron.. A-similar situation hoids.to,'

a.,lesser extent for many of the' other things that'must be done during the

bombardment. y .

A normal bombardment using protons, deuterons or alphas is performed

as follows. The oil diffusion pumps are turned on and' after about- the 11

two hours which is required for them to produce a satisfactory vacuum —5 —7 (^10 to 10 mm. Hg), the water cooled target is inserted into the

cyclotron through the target port; then the power is applied to the magnet

and the dees and the gas supply is1 adjusted to give maximum .beam, ■

A bombardment using the circulation system is difficult in that- it "

is more complicated .and many more things can .go wrong. • The-'-procedure is

described below. Only, one oil diffusion pump is'turned on'since the’gas-.

is fed back through the ot.her one. Onde the oil diffusion pump is opbratan

satisfactorily, liquid nitrogen is poured into all of the cold .traps and.

the mercury diffusion pumps are turned on. The mercury diffusion pumps °are backed by a small mechanical pump attached to the "pump out" of the o ’ o ° O ° circulation system. The current on the mercury diffusion pumps is S o o increased from the minimum allowed by the controlling rheostats in

steps of one ampere to 6.2 amperes. If the current were at its maximum

value when the pumps were turned on, it is possible that the thick glass

* o bottoms of the pumps might break.. The maximum current of 6°.2 amperes is

• the value recommended by the. manufacturer for a backing pressure of •

less than 4 millimeters'of .mercury.. The circulation control! valVe” is

then opened, the mechanical pump disconnected and the capsule containing

He3 is fastened to the' system.' This allows the oil diffusion pump to

•evacuate both the cyclotron proper and the circulation system. Once

this evacuation is completed,' the control valves are closed and the He^

is introduced into the circulatidn system.-- The target is then put into

the cyclotron and any-air whiqh leaked in during the process is "pumped

out through the oil-diffusion .pump and the Hyper Vac 100. • Power .is then

applied to the dees and magnet. ’ The_valve leading to the Hyper Vac 100

is then closed and the 'two inch valve to the mercury diffusion'jpumps is

•opened. The gas circulation-control‘valves ’are adjusted for maximum !

beam and liquid hydrogen is’.put' into its trap. A trial run using 2 cubic

centimeters of hydrogen in the circulation system gave a beam about l/lO

the regular proton beam. There is, however, a°residual proton beam

which is appreciable even without gas being introduced into the cyclotron.

This residual proton beam is probably due to water vapor in the air

which leaks in, and to outgassing of hydrogen from the metal of the

o cyclotron. -15-

At the end of the bombardments, the He3 or gas must be collected

and purified of any air -which has leaked in. A small mechanical pump is

attached to the output of the Hyper Vac 100 and the He3 or h 3 is collected

over oil at the output of the small mechanical pump. Figure 2 is a

diagram of the collection system. After the initial collection the

system is flushed several times with air let in at the pump out of the

circulation system. A total of about two hundred cubic centimeters of

air is used, which is considered enough to remove most of the He3 or h 3

in the system.

It might be thought that one could merely fill up”the cyclotron tank

with He^ or to the proper operating pressure (*vicr^ mm. Hg) and then

shut the pumps off and make a bombardment in a static system. There are

at least two reasons -why this cannot be done. The first is that air

leaking into the cyclotron would quickly ruin the vacuum, and the second

is that there is an outgassing of hydrogen from the metal in the tank.

It would be possible to freeze out the air with a trap containing liquid

hydrogen, but so far no method of getting rid of the outgassed hydrogen

has been successful, although both palladium black and hot copper oxide

have been tried. The absorbing power of palladium black for hydrogen

decreases rapidly with decreasing pressure, and at the operating pressure

of the cyclotron, it is far too small to absorb the outgassed hydrogen.

Copper oxide reacts with hydrogen to form water but at such a slow rate at the low pressures present in the cyclotron that it too is unsatisfactory.

It also' has an appreciable vapor pressure at the high temperature needed to react with hydrogen. -16-

CoHeoted Gas

Oil

To Output of

Hypervao 100

Mechanical Pomp

Figure 2 PURIFICATION OF HE3 OR H3

At the end of a bombardment, the He3 or is diluted with many

times its volume of air and hydrogen. Before another run it is thus

necessary to purify the He^ or at least to some extent. So far the

only purification attempted has been the freeing of the air from the

He3 or h 3. The He3 is freed from air by freezing out the air with

liquid hydrogen. An apparatus for doing this is shown in Figure 3•

It consists of a Toepler pump with a stainless steel freeze out trap

attached to it.

The purification procedure starts by pumping down the system with

the mechanical pump. The stopcocks to the He3 or h 3 plus air containers

are opened and liquid hydrogen is poured around the trap. The mercury

reservoir is raised so as to compress the gas into the trap. After a

few minutes the freezing out of the air is complete, and the gas

remaining in the system is pumped into the topmost container by raising

and lowering the mercury level and operating the appropriate stopcocks. 3 1 It has been found that there is some gas other than He or H"^ which is not frozen out by this procedure. Since there is an appreciable

residual proton beam in the cyclotron, and since the vapor pressure of air at liquid hydrogen temperature is very low, it is assumed that the

gas is hydrogen. About 25 cubic centimeters of this gas is obtained per each run of 12 hours. xt is thus necessary after two or three runs to purify the He3 of this gas. To date no satisfactory procedure for doing this las been worked out. A palladium tube hydrogen leak is being, made to perform the separation. Because of this hydrogen which contami nates the He3 or h 3, the outlook for reusing H3 as a bombarding particle

- \ 7- -18-

Vessel for Purified He

Liquid Hydrogen

1 liter flask

To Meahanical Pump

• Hg

Hose

Figure 3 -19- ® *1 O •is bad, The separation of Hx and h would be much more difficult than

that of H-*- and He^. If it is possible to perform the H-** and He^ separation, O then with reasonable care a few'cubic centimeters of He 3 should be enough © for many bombardments. RESULTS

The results of the bombardments with He3 and will be given in

this section. There are still several bombarded samples being followed

in their decay so that the record is somewhat incomplete. However, the record on most of the bombarded samples is complete. Due to the

short half-lives and/or low intensities of many of the induced activities,

it was impossible to do more than determine the half-lives. Whenever possible, aluminum absorption measurements were made of the beta energies.

The method of identifying each activity will be indicated.

The radioactivity in these samples was followed by means of Geiger tubes and scaling circuits. The Geiger tubes had from 2.5 to 1.8 milli grams per centimeter squared end windows; they wex-e commercially made tubes obtained from Tracerlab or Victoreen. The scaling circuits were made by Berkely, Tracerlab, or The Atomic Instrument Co. The size of the samples' bombarded was in the range of five to one hundred milligrams in most cases. The energy of the beam of particles was calculated from the known values of the frequency and magnetic field.

Beryllium

Beryllium was bombarded with 21 Mev He3 ions. By using a magnetic

__ - field to separate ^3 from ^ particles, a strong 22-minute positron ° activity was followed over about ten half-lives. From the half-life this activity was assigned to C ^ - through the reaction B9(He3, n)C^. C ^ has assigned to it a 20.5-minute positron activity.* There was also ob served a two-hour positron activity which is considered to be the 1.87-hour

This same F"^ activity was observed on many other samples.

*See the section on Carbon.

- J 6 ' - 2 1 - „ ® o © © O © o a Carbon ° 9 ° *■ * Carbon was bombarded with 21 Mev He^ ions. kAstrong,20.74-minute „ o activity was followed over 15 half-lives. * From the Jbalf-life .this

1# 2, 3, 4 There was also observed a small amount of the two-hour 4* fluorine activity. The® decay curve for this carbon sample is given in

Figure 4* The carbon bombarded in this sample was obtained from the

Hilger Chemical Co.

Oxygen

A sample of Pb^O^ was bombarded with 13 Mev He^ ions. The first reading on the sample was obtained about two minutes after the bombardment

o ended. A strong 2.06 minute activity was found, followed by a 1.8-hour activity which had a (^particle associated with‘it of 0.6 Mev. 'From the

0 © half-life the 2.06 minute activity was assigned to 015 which can be produced through the reaction 0^-^(He^, „He^)0-*-5. At present 0 has

I o 5 6 V 3 Q Zl ° assigned to it a 1.97-ininute ^ activity. ’ 1 ’ ’ ’ From the half-life and energy of the Q particle the 1.8-hour activity was assigned to pl^, which is a. 1.87-hour pure positron emitter. The reaction 0-^(He3, n)Ne^. Since no activity was found that could °be assigned to this nucleus it seems .reasonable'to conclude that the half- % 4? o a o life of Ne-L® must be considerably shorter than the two-minute half-life o of 0 ^ . o ® © 0 * An excitation function for the 1.8-hour fluorine activity was o © ° obtained,by bombax-ding a stack of alurjpinum foils. The activity produced ° a © by He^ in the oxide coating of the foils was followed, and the«activity e © © © ©

DECAY CURVE C + He

20.74 Min

1.87 Hr <

Hours After Bombardment

Figure 4 of each foil was extrapolated back* to time the bombardment ended, ^his « o * ® '■K initial activity was then-plotted as a function of the energy of the He-3 3 ion at the corresponding foil. The energy versus range curve for He O was calculated from the energy versus range curve for alpha particles.

9 The excitation function so obtained is shown, in Figure 5. „

The 1. H-hour fluorine activity ■*-*-* ^ 3 10, 4 was found on almost all of the samples bombarded by He^. Even a piece of gold that

9 was bombarded was found to give this activity. It was found, possible to get rid of the oxygen from which this activity is prqduced by putting the samples t'hrough the reducing atmosphere of a hydrogen furnace. If

o the temperature of the hydrogen furnace is*adjusted to the right«value

’ 9 for each sample, the oxygen combines with the hydrogen to form water.

It is not possible to get rid of the oxygen in all cases since such com-

O ' o ° 9 pou°nds a§ Ti09 are not reduced *in a hydrogen furnace. O V ' • * 9 * s • Aluminum 0 • • 9 9 Aluminum was bombarded with both 21 Mev and 13 Mev He^ ions. A • 9 * IS • l.S-hour activity was observed and is considered to be the F* . No . * *. • • activity produced from aluminum was observed. Many of the samples*were# 9 o 9 mounted in aluminum during the "bombardment since” aluminum pro.duced no • «0 characteristic activity.# ® #

Silicon , G O Silicon was bombarded with 13 Mev He3 ions. A 2.64-minute activity © e ^< *\ 1 r * -I rt I ® was produced which.is considered to be the 2.55-nri.nute P-;U, x:>> x Q 9 o O This activity'could be produced by the reaction Si^(He^, n)S^-^— © o o

—24— ® © © P P

P O

50 ENERGY vs. YIELD 40 30

17 1 8 19 20 21

® ® * ® @ ® of greater than 2.5 Mev energy; P-^ decays-by emission of a jP,5 Mev © .positron.® ® ® © @^ ® @ A 2.6-hour activity was. also .found in silicbn. From half-life® to O O O ' . O o ® ® ’considerations this activity was assigned to Si^l which decays by © ^ o 17 IS 19 ^ electron emission on a 2.8-hour half-]S.fe. * © * 9 © This activity ° * © ^ ° © o could be produced xi5om siliqpn ]py simple neutron capture® through the 0

0 ® • * reaction Si3(-'(n,y)Si31°. This reaction migivt.be if? part 'an. Oppfnheimer- ° » o °0 e o 6 • 0 e _ o 0 © Phillips reaction for He^. ©If the,, assignment ®is correct/then thjg is . . * „* © • ° ° . 0 6 e S e the only instance this reaction was observed.© © ® ® - ® „ ® a© ®© ® ® 0 o ® « ® ° °® 32 A lV-dsyr activity was found that has been eassigned to P which® ! o 0 ° 0 © ° s ® 0°° ® > could be produc ed °by 0the reaction Si^(°H^, p)p32. o® ° © o8 , V. ® ® ® ® » © ® @ e 0 © ® @ ® o © © © © . ®° ® • % 9 a % _ ° © Iron ®®ffi 0 e © ® 0© • 9 % ° 0© • S° A ’.Sample *o*f i^on was bombarded in the £orm of the two screws that

e ® ® © ° © ° ® •% hold the °sample tp the probe in the cyclotron. An 18-minute activity ’\ s®e J • eS I s “was observed which is Gcoflsidef,eds to be due to C . Tn% carbon could3 ® © • ®®* 0 ® • a © a ®_ ®® © © © © ® © ®0 o '. ® either® be in the iron as an impurity or it could be from oil vap®or from * ® . : . s®0® * thS oil diffusion pumps on the cyclotron? Cobalt ® ® 0 ® 0 * 0 •• . • 0 s 3 ® © « Cotfklt was bombarded with 21 Mev He-' ions. Only the carbon ^ancr © « ® ® ® 0 • fluorine!®activities were observed. © @ ® ® © w © - 26- _ 0 © © e , © ® @ @ ® ®/a rt "• «. 8 °® © £ © ® g,®1 © Nickel® * ® @ o ® <5 3 ® ® ® ® Nickel was bombarded with 13sMev He ions. A 24.6-minute cffctivity ® © © © A n 10 c was@pgoduced which was assigned to Cu° . This activity could be produced ® ® co- ®3C ° ° An ° ® ^ o ® An @by the reaction Ni->tf(H§ , p)Cu or by the reaction Ni')8(He-:', n)Zf\ & © Q ° 0 ® ® © ® 0 ® followed* by® tlfe decay of Zn^O to C u ^ 1. e Jhis last reaction would require

0 60 ° ° 0 ® • 3 that Zn either have& a half-life shorter than two minutes or that O it have *Q © %3 O*. • ° aO ® a hSlf-life longer thqn several days, since any activity instSe above % O 0 @ © 0 © @ 0 ® region could have been observedf A, 3*4-hour activity was also observed e ® ° s a « O , a^id °assign|jl through 6halfp-li considerations to Cu61 1$, 21, 2 2,^3 . 8 8 o .o° o a * ^ , • O e „Q 'Q.iis activity cdlxfiiobe produced by”the reaction ^i6.0(He3, d)Cu°-*-. The ®

sample was also read through iiwenty 0.002 inch aluminum foils and an0 @ 0 @ © w ® €, <5 * © © ft ** © e* ® © Ln 0 © 8 .4-hour activity observed. This was® assignea°to®ttfe®o9.4-hour Zrr © 0 & A ' ® O @ @ © © e»® 8 0« 8 62 °0 ® whioif co.fild tfe prgduced through the reaption Ni^^He-', ■ fl)Zn * This activity 0 -> 24, 25, 2b Q^ p-rould then decay to a ten-minute C u ^ which has a .. ’ 3.4>Mev" positron that could easily penetrate the aluminum foils. The®® ® ® o - “ o # . . . 0 o • . * .. ser?'ed0half-liefeeof 8.4 hours could possibly contain some ox the e ® $ ° ® ® © ° © e?© © o ° ^ ® 6l© <* ® @ ® 6 3.4-i*ou:g Cu whigh would make the oos|rved half-life a little shorter0 @ ° © © © « « © e,® © © 0 ©° © © ° © © * © 0 00 © 6 © ® 0 thap 9.4 hours. 0 e ® ^ 0 ® o . ® 0 ® 0 ® ° 0 0 ® ® © © 0 © ® a © o © ®0o ®e® 0 ° A 12.3rhour activity was ob^prvgd fewhich was assigned through half-® ® ® s • © ' * o , , . - o • , © © oZi, © O I life0considerations to Cu 0ana could be produced by the reaction 0 O - ®a o © o ° 8 I ® Ni62(He3op)Cu°^. By similar reasoning an observed 2.5-day activity 0 0 • ® © ° 0 27, 28,©29,^30 owas assigned to N i ^ which could be produced by the e ® 0 G 0 © GO @ • reaction Ni5^(Hq?, o O N v ^ . 6. ° 0 ° ' O ® ® ® ® ©© _ ® . @ so© ®© Germanium 9 ©_ o° ^ a . © ™ © T> © © Germanium enriched ^n@Ge . to about 805© was©bomba^ded with@6 *5 Mev £k 0 ions. A 1.46-hour beta emitter was observed which decayed by a very strong

n n 0 -1 0 0 beta oarticle. From these considerations it was assigned to As ’

which could be produced through the reaction n)As^. Also « „ 77 33 . 76 ^ observed were the 1.67-day As ’ the f. 12-day■ As , s° « and the 71 “37 • 11.4-day Ge . * The respective reactions for producing these © @ ® @ @ activities are Ge?6(H3, 2n)As^, Ge^(H^, n)As^, and G e ^ ^ ( ^ , d)Ge^. ° © ® . 8 The activities were eidentified®both by half-life and by the energies.of O © © © their decay products. In©this case the wide difference in energy of the a o ® 3 0 • ® decay prgducts was a great help in differentiating the activities. © a © © © ® ® * © e o Arsenic . ® * 0 0 0 a * » © © © e « . © ® e o O . ©« 9 ® 9 * Arsenic was bombarded with 21 Mev He-3 10ns? The only activity ° ® a 0 9 t> ® „ observe?! was the fluorine activity. ® 81 ♦ 0 0 o°e s « © „» Silver « © © eSilver0was bombarded ftith 6.$ Mev 10ns.® The shortest activity ® e ■ • © • e • 9 © © IS • # o observed was the 1.8-hour F • There was also observed a 13-hour activity © « 0 ® * wd^th S 1.10 Mev beta panbicle as determined 1?y an aluminum absc?rption. . t

by the reaction Ag-^9(j|3^ He3)Pd^^. © . A © 0 © %« © © © ®_ ®^ @ © @ © A 7«5-day reaction vjas observed which had 1.0 Mev particle as ® ® S 0 © J 11 @ determined by an aluminum abosrption. This activity wSs assigned to Ag © © o » ■ oe © ® ® ® 109/ 3 \ 111 ® ® © whi ch_could be produced by the reaction Ag (H , p)Ag . @ ® © © A longer activity was also observed that, was accompanied ’by a Of 55 m ^ 1 n ® ® Mev particle and a 0.09 Mev gamma ray. This is probably AgiXU which has © 0 ® ® « ®a half-life o'f0270 days. It could be produced by the reaction A g ^ 9 ® © © ©

3 110 0 °■ © (fv, d)Ag . The sample is still being followed in its decay and contains half-lives longer than the 270 day activity. These ^onger half-lives

are probably the 470 day 44* 45 q^109 from -the reaction ® 0 « • ®109 q 109 - * ® o Ag # (H^, n)Cd and the ^2-year Y p . An alumii^pm absorption afte^-yie

shorter half lives were gone gave evidence*of an x-ray and .a gamma ray \ o ® «’ • * which could be due to th,p 470-day activity. « A windowless continuous /fi; (?) ® ,?;* . (O'. * flow proportional methane counter of about ^ 0 % gemoetry gave about 26*00 & ® <* * * . • . » * counts per second of an activity that an aluminum absorption on the same s * *<* si " r * # o " . tube showed to^be du<3®to the 18 kev be^.particle 6f H-2. The decay of W w ® * '* „ ,, * * '•I C* ^ ? '« the sample must be followed for quit© sonjp time yet before the longer H: § * ’ * *. * • « • activities’can* be definite!/ identified. * * •" i * * m • • Indium * % . ., . .. *' * «. * ' J-nd4uift was bombarded with 21 M e v sions.* The only activities •

•• » ... -| rV • . observed were the*. 20»minute C^* ariff the 1.3-shour^F • # * m • *' . <%■ * . * . ... Tantalum ® ■** 1 <•-’ .j ig) '•? ’ A tantalum foil was bombarded®vith 21 Mev y,e^ ions. The 1.3-hour '*■ .... (•' '®; ;® (*> fe', fluorine was .observed. A t ’a very-low

® . **Gold ® * * * * * ? * ? •® 0 ®c> I *4 Gol& was bfembarde^0 mt h 2J Mev He ions. The only actJ?vi»ty found @ ® © § © ® ° ® ® ^ ® „ wag ®the 1.8-hour fluorine. @ ® ® @ @ @ ® Lead ® • % ® ® ® @ ®r®® @°@ 3 0 sLead in the form of PboO, was bombarded with 13,Mev He^ iorfe. No

ac#ivity due to lead was found. A full description of the activities • ® observed may be0found in the section describing the activities of oxygen. © © © © D O © e © -29-° © © © ® ^ © ® o ° Q © Bismuth • 9 O @ ® Bismuth was bombarded with 13 Mev Hjs ions in an effort to make © • the ^8.5-hour alpha emitting At^^- by a (He-*, n) reaction. No alphas * © ® were observed. There were some short lived positrons observed about © twenty ininutes after the end of the bombfrdment and were considered * * due to * O CONCLUSIONS * e 8 • • Since the. bombardments reported0herein were the first ones ever d | © made |fith high energy He3 ions, all of the information on the types

of reactions that oc

reactions in vftiich n, p, or

the usual bombarding particles. Most of the reactions observed seemed

to be compound nucleus reactions since in almost every case at least

one proton stayed in the nucleus.* The exception to thisawas the

questionable reaction in silicon which seemed to be an Oppenheimer-

Phillips reaction of the .type that Is equivalent to an (n,Y ) reaction '■*' Cl £ or the heavier elements such, as lead and bismuth the He-5 ions did not I * a O'. ’ - ® have sufficient energy to penetrate the potential barrier and no

reactions were observed. The (He3, n) reaction on bismuth would have ® .* • 0 ® * , * » • ® given a 7*5 hour alpha emitter that would have been quite easy®to * « * *5 detects In general the reactions due to He-5 resemble those produced

by alpha particles5. • " . • * - ** . % * * The‘half-life of |o.tU minutes found here for C^-f is considered « ^ J»> © © © 's % . the most accurate value known® for the half-life of this®isotope. • . ® © ®® ® o© © a©®.®r *• & © © * Most of ®the other isotopes weise qot produced in sufficient intensity 9 ® © ® © to Improve the*known values of their0half lives. e ®° ® ® 0 ®@ $1 ® <9© © Due to the multitude of reactions produced by He3, it shows © © ® ® ® ® @ great promise o£ being useful in producing radioactive isotopes. 0 • „ 00 ® ‘ . ® 5 It is to be noted, however, that most of»the activities produced G © © either decayed by positron emission or by K capture. Thus," in 9 © © «. general, only isotopes°belcw the line of stability will be produced o o © , by He3 bombardments. ® ° . © & • The bombardments with h 3 also showed that it is a prolific

. 0 * . ° • ° « o producer of reactions. ihe reactions produced Ranged from the usual ® ® <5Q neutron §nd proton emitting reactions to the more unusual ones® of © deuteron and He3 being emitted. The opportunity for an Oppenheimer-® © ° ® Phillips reaction is much greater for h 3 than for He3 since h 3 has

® o two neutrons in itj such a reaction was in fact probably observed as

of two neutrons to the stable isotope Ag^-0?. With h3 bombardments * * . * o ® it.is possible to produce beta emitters on the high energy side of •

* * 9 the line•of* stability* TJlus the two new bombarding particles H3

and He3 should be very useful additions to the family,' of particles

that can produce radioactive isotopes. * * 9 ♦ * ♦ . Last but not least, it has been conclusively shown that 8 *■ * * » it, is* possible to make cyclotron bombardments with only a few cubic '♦ » 9t centimeters of the gas with which the bombardment is being made and *■ ® ** # ' * that it is possible to recover tljis gas after* a bombardment for re- ® • REMtENCES © @ ® % © ® @ -'-Smith, J. R. C., and Ccmie, D. B. "Measurements of Artificial Radioactivity in Liquid Tracer Samples Using C H . " J. Appl. Phys. 12 (19U1), p. 79. • ® ® ® ^Solomom, A. K. "Half-life of C1!." Phys. Rev., ®60 (I9lll), p . 27 9 • ® ® o Lithium-Gamma-Strahlung Quanl§nenergie h0=17«5 Mev." Helv. Phys. Acta, 21 (19U8). p. 200. A © ^ X ® ® . * ? e ®Sherr, R.®S., Muether, 5. R., and ^hite, M. G. "Radioactivity of CIO and O1^ Phys. Rev.,®75 (19U9), p. 282/

^Perey-Mendez, V., and BroWh, H# "The Beta-Spectruro‘of .0^5"., • Phys. ftev.^ 76 (19^9), p. 689. ®® & ® * a e ^ ® » lOSnell, A. H. ®"A New Radioactive Isotope of Fluorine."* „ r. Phys. Rev., 5 l @(l93l),° p. ll+3 °(A). ® « © U © ©' © ©_ ® 0 ® ®_ ? HDuBridge, L. A°, Barnes, S. <8uck, I. H., and Strain, G. V. "Proton Induced Radioactivities." Phys. Rev., <53 (1938), p . 14*7* @ • ® ® ® © ° 1 4fuber, 0., Sherrer, P., and Waffler, H. "Der Karnphotoeffekt> mit Lilhium-Gammastrahlung. ®I. Die 'ieichten Elementl bis zurn Calcium." Helv*! d’hys. Acta.,®l6 (194U), p. 33* o ^ © (g? © o ■^Blaser'i® J. P., Boehm, F.,®Marier, ip. "The Posi'Sron Decay of Fl8.w. P h y s R e v . , 75 (l9k9), p. 1953 . 0 © ' c ^Knight, ®J. D. et^il, "Activities from pBLtuim Bombardment ® Neutron Irradiation of Lithium Salts: (t, n) Reaction on^Dxygen o® and Sulphur." N. N. E. S.®9 (1950), p. 326,®® © 9 ^ R i d e n o u r ^ L . ®N., and Henderson, W. J. "Artificial Radio- AStivity Produced by Alpha-Part^cles." ®Phy s. Rev., 52 (1937), pf 889? 8 ® ® ® ® 0 % # 'fj) # 9 ^ ^ ^ ^°Qhichoki,° J., and Soltan, A. "Radiofilicium Produit*par Bombardment du Soufre avec des Neutrons Rapides." Comtes rendus, • 207 (1938), p. U23,. ® , . » * ' *, ^ ’* »■ ^ '* * - <•: % .. „ ^Allen, V/. D., and Hurst, C. "The Scattering of D-D Neutrons." Proc. Phys. Soc., London., 52 (19U0), p. 501c-. * l*;’ ^ © 'K fc >> 0 A « (•• >*■ -®’- ' ' ' ,-y 'S' Phillips,JD. D. -"Inelastic Collision Crgss Sections of*Various ® Elements for ll; Mev Neutrons." A® E.^C. U., °(19i:9), #l|0li. f **./ *, *’ r#) &'J - 1*, _ ® it) S' ‘S® - * '♦ i! '*! 1 /s- i») ’A’ r. 0 0 0 'S' ^ * L*‘ " I Q ^ '~J '*J ~ ,y, ,s> ^ ^ xyLuscher, E.,®et al*,*iM«Uber®die EnergieabhangLgkeit der Prozlss % S32(np)p32 und .p31(n p )Si31-.» • HelVa. Phys. .Acta; 23 (l950)y p. 561. „

O ® * ® © ’ * S 3 s. W « «’ ® ® ® « ,® *.-> e ® * ® * “ ® ? © © s - © ® *g, ^^Leith, C. *E., Bratenahl, .A,, and^ Moyer, B. J. . '.’Radioactivity of Cu60.» ghvst Rev., 72 (19U7), p. 732%i® ® ® * * ‘ ® ® « (V) v S @ (

® ® ^-Thornton, R. L;. "The Radioactivity .Produced 'in Nickel by s © ® ' » (?) Deuteron’Bombardment5." .Phys. Rev.,®5l (1937),' p. 893* © _ ® G ^ ^ * ® ® 0 ® ^ ^ ^ « • * * * •* ® oo ® ® ® ss ® g ® ftSJ ® ® 15 ®„ ® ® @ ^iCook,@C. S., and Langef, Li M..: v"Shape of@the Positron Spectrum (’ ®of C\Pl.« Phys.'Rev., % (19^0), p.® 227. ® H 0 ® a® ® ® ® ® ® ® ® 0 0-i, c-s ff a ° ® 0 ® s® © **® | f " QO -9) © ^ © ®® fi’ © © © rig 9 @ °Bouchez, R., and JCiyas, G. "Sup les Interfsites Absolves desa *’J Rayonnements Ends par ^ C u ets^klu." jf de Phys et Rad0.,0 (8)° 10® (19U9J, P.®iio.«© ® . ©e 0 v © <*•' n) * .<$> ® g ® o 0 ® ® ©

M_ '^Miller, D. Rs>, Thompson, R. <£., and Cunningham, B. B . -;. "Products ® of* High Energy Deuteron ’and Helium Ton BombSrdments of0 Copped." Phys. ® •fev., 7U®QL9U8), p,„3i*f. ®° ® ® 1 " / © (*> ^ (•) r.) 0 {j ® ® 0 ,, <'•© ® ® •, ^Hayward, R. W. "The Beta-Spectra of Zn^2 and. Chj62.« Phys.’’ - «" Rev.,. 78 (1950), p. $ (A). ^ .Oj rf. " ® s> R. gf. "The Beta-Spectra of Zn^2 and C u ^ . n Phys. Rev.,. 79 (1950), p. -5iil. " ? *, * , a - - „■ ,6 ® D_ i®; ' ,0' # ' / 'e' ® ^ io; ,• ^Li^ingood, J. J.„and Seaborg, G. T. "Radio Isotopes of Nickel®" Phys. R e v , 53 (1938), p. J65. ® * « * . ® @ OR 0 Huber, Ot , Lienharc^,* 0., and Waffler, H. "Der Kernphotoeffekt ® mit Li%hiurn-Gammastrahlung: II. Die Elements Titan bis Rubidium.” ® Helv. Phys.@ Acta., 17(1910*), @ e p. 195.® 0 ® o ® © ^Mailnschein,®F., and Meen/ J. L., Jr. “"Coincidence Experiments in0 Ni65, Ni57, A g .°, and In111*.* Phys. Rev., 76 (191+9), p. 899.* *. &• " * * $ "• * * , ' 3Opriedlander, G>., et* al., "The Decay Scheme of Ni57.ii Brpokhaven , National Laboratory, S-5 (l95l), p. 1*6. * * , ? ... ’* ' * • . 3,-lCurtis, B. R., and . Cork, * .■ ;ai ~ ~ o.0 ® * * o ^'2Sagane, R., Kojima, S., Miyamoto, G., and Ikawa, M« "Radio- ,« active Isotope's of Cu, Zn, Ga, and Ge." Phys. Math Soc. Japan Proc.,' ! u 51 (1939), p. 660. * „* / * ** *

33Mandeville, C. E.,« et al., "Radiations from Ge?? aril Ge?l." wPhys. Rev., 75 (3^1*9), p. 1528. ss * *»_ * & p ® '

®® 3^Mitchell,'A. C. G.,“Danger, and McDaniel, P. W 5.® "A « ’.Study of the Nudlear Radiations fiom Antimony and Arsenic." Phys. 'Rev.,.57 (191*0), p. 1107. „ is," O ® . -1 l*) o' ® ® ' o (.') -,-?Weil, G.. L,» "Beta-Ray Spectra of Arsenic, flubidium, sand Krypton.*-, Phys. Rev., 62 (l9U2),®p. 229. i1 0 ® ® ^ ® S) 0 ^ ® (S S (•' r ® o (i) ® ® ® (S® -JOPhillip, K., ‘ and - Rehbein, F. *Energiefra-gen beim Kunstlick ® Radioaktivin ?°Arsen." Zeits f. Physik, 121* (19U8), p . 225. ® 0 ® m (ii ® * ® 0 ® ®® 97 ® » ® ” ° ® ® ® ® % ^'McCown, D. A.®> Jfoodward, L. L., and Pqpl,®M. L.® "Radioactive® Isotope's of Ga sind Ge." Phys. Rev., fit (191*7 ),* p. 1131i® . ^ ®

,, ' ® 38ftQynoixis, s. . A» "Analytical Chemistry Division Quarterly ® ’ Heport for Period Ending October 10, 1950." B. N. L. # 867•(1950), p. 21*'.- * * ' . " .... , ft; *■ . ° ® ''

35m o c 1c, D. L., Waddel, R. C., Fagg, Li W., and Tobin, R. A# . "Photo-Induced Reactions at 20 4Iev»" ® Phys. Rev.,@7l* (191*8), p. 1536. '*■ @ © ® J® ^ $L ^ - l*0siier, J. A. "Palladium-Silver Chains in Fission." N. N. E. S. 2 (1950), paper 119. °° ® ® ©® © ® © . ® a® ,I t ® ® o o ® ® © ® ° ® ®@ ^Bergstrom, u., et> al°., "An Electromagnetic Isotope Separator."® Arkiv. f. Fysic., 1 (1950),®p. @28l. @ @ g ® © @ © .-35- e 1 @ 0@©v @ O ^^Helmholz, A. C. "Long-lived Radioactivity Cd from Deuteron © © po o Bombardment of Ag."0 Phys. Rev., J>0 (19U1), p* 16QA.s 8ft ° ® © a « © ^3radt,0H., et al. 0 "Die Silberiqpmere Ag*107 und a^g109.« Helv. Phys. Acta., 19 ®(19U6), p. 218S

^Gum^ J. Thompson, L. E»,* and Pool, ll.JL# "Silver and , Cadium Activities."0 Phys. Rev#, 76 (19U9), p..lSl^A). • * • %* . * . • *' ** ■* »* . » »■ * * . ^Gum,‘‘J. R. ,•and‘Pool, M. L. "Radxqactive Jsotopes of Ag and Cd." Phys. Rev., 80 {1950), p 0.315* “ * * * :i *« -

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J © AUTOBIOGRAPHY © ° © © © ^ © © © o© ■ e @ ( I, Thomas William Donaven, was born in Denver, Colorado,® o © a o © @ November d.5, 1923. My primary and secondary education was received© o o ® ° ° ® r> @ ® in the schools0in and around Dodge City, Kansas. Several honors were © ° ® ^ received in physics agd chemisstry.®® My undergraduate work was obtained

© ® ® a © at the Univdirsity of Missouri, where I received a B.S. in physics. O o 0 o ® @ ©6 ffl ® © c An M*A® i n 0phgrsics was also obtained at the same school* @ During®the® o O ® q © 9 d a ® 0 o ©.©. C* G © Ge©©© G © © © year 19h? - ho, I held the position of. Graduate® Assistant in the® e O © © Depa^tmei^t of Physics tlfere. °In 19Up - h9, I held the «0.oM.° Steward 0 0 e° ° ® 8° 0° S0O° ° • ® Felldwship at ^.hat scho®l. ° From 19U9 to 1952 I attended „the Ohio ® » ° " « 0 ° s o° • °s® ° ® © O ® © 0“^ _ _ ® © 0 0 O © © O 0 ® o ^ ' © © o State University, wjiere I held a Research Fellowship in Physics from a # ... * ® . ° a ® *• ® sS0° ° °° 1§5C? - $1 andean A •.E .. C.*Fellowship in*Physics from°T95l - ° ® ® ^ a o » 0 ^ 0 a ® ® Q® ® ® o ° .* * . . * ® . » » 9 .During this .timeeat Ohio State, UniVei’sity ny work was undey *the " o • * » « • * . . **. \ ® ® A • 0 © ° direction .of.Professor M. h. .Pool. . * * *• • • * . .

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