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NBSIR 83-2734

An Investigation of Lyoluminescence

Techniques for Application in

Radiation-Protection Dosimetry

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Center for Radiation Research

Washington, DC 20234

August 1983

Final Report

national bureau

OF STAUDARUS

UBRAfiy

SEP 1 5

NBSIR 83-2734

AN INVESTIGATION OF LYOLUMINESCENCE

TECHNIQUES FOR APPLICATION IN

RADIATION-PROTECTION DOSIMETRY

Richard E. Hanig

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Center for Radiation Research

Washington, DC 20234

August 1 983

Final Report on Work Performed by the Author

during the Period from January 1980 to January 1982

on a NBS-NRC Post-Doctoral Research Associateship

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

An Investigation of Lyoluminescence Techniques

for Application in Radiation-Protection Dosimetry

Richard E. Hanig*

National Bureau of Standards, Washington, DC 20234

ABSTRACT

A cooled liquid scintillation system with single-photon-resolution

photomultiplier tubes was employed to increase the sensitivity of luminol -enhanced lyoluminescence (LL). The problems of reagent purity and

mechanical mixing were studied. For the disaccharide trehalose, the

lowest dose significantly different from background was at the 1.2-rad

level for ^°Co gamma rays, with a relative standard deviation of 33 percent. The system suffers from poor reproducibility in the mixing of the

di saccharide with the solvent, and recommendations are made for improvements. Detector compounds of different hydrogen content were studied

for possible application in neutron dosimetry and for their ability to

retard free-radical recombination. The results were not conclusive.

Enhancement of the LL effect was accomplished by radiation sensitization

of solutions of trehalose with irradiations between 30 and 300 krad to

water. The di saccharide was then recrystallized from solution, along with

associated radiolysis products and, in some instances, with separately

added chemical dopants. Preliminary intercomparison of these doped' sugars

with untreated materials at doses of 1 , 5, and 10 rads indicates that

they give a better signal-to-background ratio than the untreated di sac- charide. A promising reaction model was postulated which assumed a twocomponent exponential decay of light, multiplied by a first-order

buildup term for the dissolving factor. The model seems to fit both

the ordinary and luminol -enhanced LL glow-curves.

*NRC-NAS Postdoctoral Research Associate, 1980-1982.

1
CONTENTS

Page

Abstract 1 List of Tables iii

List of Figures iii

1. Introduction 1 1.1 Brief Overview and Goals 1 1.2 Brief Summary of the Light Emiss'*' ocess in

Lyoluminescence 2 1.3 Radiometric Characteristics or Lyoluminescence

Dosimeters 3

1.4 Factors Affecting Lyoluminescence Response 5 1.4.1 Solvent Factors 5 1.4.2 Sensitizer Factors 7 1.4.3 Sample Factors 9

1.5 Luminol Chemiluminescence Assays and the Application

to Lyoluminescence 12

1.6 Lyoluminescence Readers 13

2. System and Procedures Chosen for This Work 15

2.1 System Chosen 15

2.2 System Setup and Calibration 16

2.3 Preparation of Readout Solutions and Samples 17

3. Brief Summary of Experiments Performed 19

3.1 Advantages and Disadvantages of Using Low-Temperature

Readout 19

3.2 Effect of Luminol 19

3.3 Influences of Increased Reagent Purity 20

3.4 Baseline Data for Different Detector Compounds 21

3.5 Attempts to Improve Reproducibility 22

3.6 Use of Dopants 23

4. Reaction Model 25

5. Conclusions and Recommendations 26

Acknowledgements ' 26

References 27
LIST OF TABLES

Table 1

Table 2

Figure

Fi gure

Figure

Figure

Figure

Fi gure

Figure

Fi gure

Figure

Figure 1

Figure 1

Page

Summary of the Properties of Lyoluminescence Materials

Used in Studies Appearing in the Literature 34

Factors Affecting Lyoluminescence Response 40

LIST OF FIGURES

1. Timer-Dumper. The sugar sample ('x^lO mg) is inside

the detachable hollow rod (B) connected to the wheel

(C). The wheel spins and pours the sugar into

the solution. The time span from turning the switch

(A) to "on" to pouring the sugar is ten seconds.

The vial is a liquid scintillation vial with the

top cut off and replaced with a plastic holder for

the timer- dumper.

2. Block diagram of LL reader using the housing of a LSC.

3. pulse height spectra (linear scale) taken with

RCA 8850 photomultiplier tubes, showing the single,

double, and triple photopeaks. (A) Spectrum taken

with a single tube. (B) Spectra taken with two tubes

brought into "register", so the peaks line up; the

distribution from one of the tubes is visually raised

for clarification.

4. Comparison of the pulse height spectrum of and of

luminol. In the scintillator PPO-toluene, produces

a burst of photons, creating the additional peaks with

greater pulse heights, whereas luminol in reasonable

concentration is a single-photon emitter and produces

only a single peak. The spectra are visually offset

for clarification.

5. Improvement in counting geontetry. (A) Present geometry.

(B) A1 reflectors added.

6. Typical lyoluminescence "glow curve".

7. Relative response-vs-dose for trehalose, dissolved in

0.1 N Na 2 C03 for LL readout.

8. Relative response-vs-dose for trehalose, dissolved in

luminol for LL readout.

9. Relative response-vs-dose for 2-deoxy-D-ribose, dissolved in luminol for LL readout.

0. Relative response-vs-dose for vitamin C, dissolved in

luminol for LL readout.

1. Enhancement factor-vs-sensitizing dose (^°Co gamna

radiation) for trehalose, dissolved in luminol for LL

readout. Three levels of ^°Co gamma-ray test exposures

were given to the solid trehalose. These are preliminary

data with a relative standard deviation between 20 and

50 percent.
LIST OF FIGURES (Continued)

Figure 12. Enhancement factor-vs-dopant concentration for three

dopant modes of trehalose, dissolved in luminol for

LL readout. Identical test exposures (5

gamma radiation) were given to the solid

rad of ^°Co

trehalose.
1 . INTRODUCTION

1.1 Brief Overview and Goals

There is a strong need to search for materials that exhibit phenomena

that would be applicable to fast-neutron dosimetry. For accurate fastneutron dosimetry, a dosimeter must respond over a range of nine decades

in energy and, over this energy range, its response must parallel the

fluence-to-dose-equivalent conversion factor (ICRP-71). An equally

important property for a fast-neutron dosimeter is the capability of detecting a neutron absorbed dose in mixed radiation fields having gammaray-to-neutron-dose ratios greater than ten. The dosimeter should also

be able to detect a fast-neutron dose equivalent as small as ^10 mrem and

have good signal stability. Other considerations are that it should be

non-toxic and cost effective for the nuclear industry.

There are no currently-avai lable personnel neutron dosimeters that

meet all of the above criteria, and specifically, there appear to be no effective neutron dosimeters for the energy range of 20 keV to 1 MeV.*

Lyoluminescence dosimetry (LLD), however, may have the potential to meet

many of the above criteria.

LLD is the evaluation of lyoluminescence in terms of absorbed dose

to the material of interest. Lyoluminescence is the emission of light

accompanying the dissolution in water of certain previously-irradiated

solids. Examples of lyoluminescent materials are alkali halides (including LiF commonly used in thermoluminescence dosimetry) and saccharides.

The energy dependence of the response of the saccharides is particularly

attractive because saccharides are nearly tissue equivalent for both

neutron and gamma radiation. The mechanism of light emission for alkali

halides has been postulated as being both the recombination of hydrated

electron-hole pairs and the recombination of trapped free radicals, both

^Robert Schwartz, National Bureau of Standards (private communications).

1
entities being radiation induced. The latter mechanism is also used to

explain the response of saccharides. To improve the radiation sensitivity

of saccharides, a sensitizer such as the chemiluminescent compound luminol

is added to the solution. Upon dissolution of the irradiated solid sac- charides, the luminol is oxidized by the radiation- induced free radicals

that are trapped in the matrix of the solid.

The goal of this research is to ii. ^tove the sensitivity and reproducibility of lyoluminescence by using different instrumentation, using

purer reagents and sensitizing agents, and using new and doped phosphors.

Also modeling for the light output vs time may help in evaluating future

spectral and kinetic data.

1 .2 Brief Summary of the Light Emission Process in Lyoluminescence

For a complete understanding of the mechanism of lyoluminescence

(LL) it appears that more precise spectral and kinetic data are needed.

The character of the observed light may depend on several competing

mechanisms and on conditions of dissolution, type and nature of radiation

dose and, of course, on the type of phosphor.

For alkali halides or other inorganic materials, LL is believed to

be caused by electrons freed from F centers (Ah-66). It. is postulated

that dissolution in water results in the hydration of the electron-hole

pairs created by radiation, and in turn these pairs recombine with the

emission of light.

% It has been shown (Lo-61) that in organic materials such as sac- charides, trapped free radicals are involved in the LL process in a manner analogous to the reactions of the trapped electrons from the F centers in the alkali halides. According to Atari and Ettinger (At-73b)

when solid saccharides are irradiated, some of the energy is stored in

the form of stable free radicals. When the material is dissolved, the

free radicals can react freely in the solvent. Possible reactions may

2
include recombinations of free radicals, reactions with dissolved oxygen,

or reactions with the solvent resulting in the emission of luminescence.

For example, Ettinger (Et-82a) has speculated on a reaction mechanism he

labels the Russell-Vassiliev scheme. Once an alkyl radical has been

generated by ionizing radiation the following is one of the reactions

that take place:

R +02"^ RO2 .

And out of many possible reactions,

RO2 + RO2 non- radical products

is one of a small minority during which light is emitted.

Other mechanisms for LL involve the generation of singlet oxygen or perhaps decomposition of hydroperoxide. Reactions that may compete with

the ones mentioned above involve perhydroxyl (HO2 ) and superoxide anion

(O2 ”) mechanisms. For details see Ettinger (Et-82a) and the references

listed there. Mechanisms involving luminol have been discussed in the

literature (Wh-63a, Wh-63b, Bo-75, Ma-73, Bo-68, Sc-76, He-70).

1 .3 Radiometric Characteristics of Lyoluminescence Dosimeters

The materials whose LL response have been studied by various investigators are briefly summarized in Table 1 (pages 35 through 40). The

dose range over which the response was studied as well as the range of

linearity of dose and response are included whenever such information was

provided. The gamma- ray energy dependence has been studied in only a few

cases (Pu-77 and Et-77a).

It is not clear in most of the cases cited whether or not the low

value of the range studied is a detection limit. For many of the studies

cited, the dose rates were not specified. The LL response may be dose3
rate dependent, although Ettinger and h1s coworkers (Et-77a) found no dose-rate dependence for saccharides In the range of 3 rad/mln to 18.5

krad/mln.

It appears that the radiometric properties of LL dosimeters may be

altered by the method of readout. Avotinsh and his coworkers (AV-81)

have extended the linear range of L1F LL by using a rotating disc method

and slow dissolution In sulfuric acid.

Although most of the studies on LL dosimetry have Involved the use

of gamma radiation (usually ®°Co or ^^^Cs sources), It would appear that

the most Important use of LL would be In neutron personnel dosimetry.

Ettinger et al . (Et-77a) have pointed out that saccharides, because of

their atomic composition, approximate soft tissue for neutrons and mesons. Saccharides are somewhat deficient In hydrogen, however (a con- tent of about 1 % vs 10% for tissue), which may be of concern In the

100-eV to 10-MeV range. On the other hand, the amino acid valine, with

a hydrogen content of 9.4 percent, may be very suitable for neutron

dosimetry. Ideally, a suitable compound should have 10 percent hydrogen,

be a solid that Is not deliquescent and be soluble In water or other

solvents to which sensitizers may be added. A compound that seems to

meet all these requirements Is di ethyl dithlocarbamic acid diethyl ammonium

salt. The author has tried this compound in luminol solutions and unfortunately there was no response at a gamma-ray exposure level of 1 rad.

Some aspects of sensitivity will be mentioned later.

Although amino acids appear to be less sensitive than saccharides,

Ettinger's group has investigated the neutron response of valine relative to its ®°Co gamma-radiation response for 2.5-MeV, 7.5-MeV, and

14-MeV neutrons. They found a relative response of 0.8 in the 7.5- and

14-MeV range, and a relative response of 0.5 at 2.5 MeV. These data

appear to be more reliable than the data by Ahnstrom and Ehrenstein

(Ah-59) who observed that the neutron response of crystalline glucose

relative to its ^°Co gamma response produced 5 to 7 times more lumi- nescence.

4
Puite (Pu-77) studied the neutron response for mannose. He found

that the LL per rad relative to ^°Co gamma rays was 0.24 for neutrons in

a degraded fission spectrum, 0.45 for 5.3 MeV neutrons and 0.60 for

15 MeV neutrons. See also Si-76.

For a more complete discussion of energy dependence see the review

articles by Ettinger and Puite (Et-82a, Pu-82) and the papers by

Bartlett (Bar-81, Bar-80).

1 .4 Factors Affecting Lyoluminescence Response

In conducting LL research or in using LL for practical dosimetry,

attention must be given to controlling a number of factors which may

affect the light output from the sample. Based on the available literature, a summary of these factors is given in Table 2 (page 41). The

table includes only those factors associated with sample treatment and

readout, and does not include dose, dose rate, energy or LET factors

which must also be considered as for any dosimeter system. A brief discussion of the factors applicable to practical dosimetry listed in the

table is given here. For details, the reader should consult the reference

1 is ted.

1.4.1 Solvent Factors . In studies on the alkali halides. Atari and

Ettinger (At-73a, At-74a, At-57) used distilled water and TlCl solutions

as solvents. Compared to water, the fluorescent TlCl solution enhanced

the light yield 200 times for a 500-krad dose. The degree of enhancement

decreased with decreasing dose, dropping off linearly from 10^ krad down

to 1 krad, and fading to zero enhancement below 1 rad.

Ettinger (Et-82b) has achieved LL enhancement from the amino acids

glutamine, threoine and serine, in solutions containing Tb^^ ions at a pH of 2. The increases after phototube spectral -response corrections were 700, 330, and 245, respectively, for these amino acids. For sac- charides, only glucose showed a slight enhancement using the above solu5
tions. Thwaites and co-workers (Th-76) indicate that, for irradiated

amino acids, the light yield can be extended by using a solution of NaOH

instead of distilled water. This enhancement is probably related to the

pH of the solutions.

Laflin and Baugh (La-79) have observed LL in an aqueous solution of

micelles containing di phenyl isobenzofuran (DPBF) at a concentration of

10" 5 mole/liter with an enhancement for irradiated carbohydrates of 10

as compared to pure water.

Some of the problems of reproducibility of LL may have been solved

by Avotinsh and co-workers in the case of LiF (Av-81). They use a rotating disc made of a single crystal of LiF which, after irradiation,

is dissolved in concentrated sulfuric acid. The dissolution time is

very slow and is a function of angular velocity of the disc. In the

Mrad range, after initial start up, the light output is constant in time.

The pH of the solvent affects the dose-response relationship by influencing the yields of reactive products that cause luminescence.

Ettinger et al. (Et-77a) indicate that small variations in pH, not

exceeding 0.2, do not change the yield by more than 1 to 2 percent.

Atari and Ettinger (At-74a) showed that the slope of the dose-response

curve is dependent on the pH of the trehalose di hydrate phosphor solution.

In the studies on glucose by Ahnstrom and Ehrenstein (Ah-59) it was found that the intensity of luminescence was a function of the pH of the

solution. These investigators found a twenty-fold increase in intensity

after alkalinization of their aqueous solutions with NaOH. Similar

results were reported by Buchan and Ettinger (Bu-75) who found that all

the carbohydrates studied showed enhancement of light output in alkaline

solutions. Glucose monohydrate was found to be the most sensitive to pH

changes. There are also other earlier results reported by Klimentov

(Kl-73) on solid polyhydroxy compounds (mannitol, saccharose, raffinose,

etriol, xylitol) which confirm the above general trends with pH.

6
Ettinger (Et-82a) has concluded that due to significant lack of re- producibility with alkaline solvents, neutral or slightly acidic solutions

should be used in practical LL dosimetry; also, that the selection of

buffers should be done with care, for the gain in stabilization with

respect to the influence of pH may be accompanied by a loss of sensitivity

due to LL quenching by foreign ions and molecules introduced into the

solvent. For pH profiles of LL and a more complete discussion, see Ettinger (Et-82a).

With respect to oxygen concentration in the solvent, Ettinger et al

.

(Et-77a) indicate in their studies with saccharides, that variations in

the oxygen concentration close to the value of equilibrium with air have

no observable effect on the light yield. In a related study. Atari and

Ettinger (At-73b) compared the effect of oxygen or nitrogen dissolved in

water with freshly-distilled water. They found that water saturated with

nitrogen had a quenching effect in some cases but not in others, while

water saturated with oxygen has an enhancing effect in some cases and a quenching effect in others. The details on material and radiation dose

can be found in the references cited in Table 2.

The oxygen effect has also been studied by Baugh and Laflin (Ba-80).

By using acetone and water solutions, they slowed down the dissolving

processes, thereby keeping oxygen in equilibrium, and found that the

abundance of oxygen determines the shape of the dose-response curve. Briefly summarizing their conclusions, it can be said that the primary

alkyl radicals need sufficient amounts of oxygen in order to be converted

to peroxy free radicals which are the ones that produce the light yield

upon recombination at or near the solid-liquid interface during dissolution.

1.4.2 Sensitizer Factors . A number of investigators have shown that

significant enhancement of light yield can be obtained through the use of sensitizers. Atari and Ettinger (At-74a, At-74b) sensitized their

solutions using luminol (5-amino-2,3 dihydrophthalazine-1 ,4 dione) plus

7
Nd2 C 03 and chlorohemin dissolved In water. With this solution, they

found an increase in the LL response by a factor of 10® for glucose and

a factor of 20 for trehalose dihydrate. The author has found a luminol

enhancement of trehalose di hydrate LL by a factor of 100 over pure buffer

solution.

A major problem using luminol is the prp^-nue of self-glow or chemiluminescence associated with the dissolv.u oxygen and impurities such as ions of iron, cobalt and nickel. The self-glow increases sharply with

the temperature. The author has found that purifying the luminol solutions with Chelex 100, a chelating resin, decreased the self-glow by 25

percent. Also, lowering the temperature from ambient to 6®C decreases

the self-glow by a factor of 10.

Klimentov (Kl-73) has found a steady increase in light yield with

dissolved oxygen in a luminol -sol id polyhydroxy compound system, with a saturation value of approximately 2.3 mg/100 ml.

In considering the signal-to-"chemical noise" ratio, Chang and

Patterson (Cha-80) have found halide ion enhancement of chemiluminescence

of trace metal ion catalyzed by luminol oxidized by hydrogen peroxide.

Their technique should be looked into in reference to improvement of

luminol-enhanced LL, in order to determine whether the halides will act

in conjunction with other impurities to worsen the system or perhaps will

work alone to enhance the light output.

In another study Ettinger et al. (Et-77c) indicated that lucigenin

(N,N-dimethyl-9, 9-biacridinium dinitrate) is a sensitizer with properties

similar to luminol. They also found that the light yield is dependent on the concentration of the lucigenin, with the light enhancement increased

by a factor of about 10*+ at a concentration of 10~® mole/ml, but then

decreased as the concentration was increased further. For details see reference (Et-82a).

8
Both lucigenin and luminol have the problem of self-glow and of decreasing LL reproducibility, which may indicate the need for a low-pH

system for good reproducibility with sensitizer-enhanced LL. A chemiluminescence system using bis-(2,4,6-trichlorophenyl ) oxalate (TCPO) has

been evaluated by Williams et al. (Wi-76). This system can operate at a pH of 4 and should be investigated as an enhancement technique for LL.

Sensitization can also be achieved by the addition of certain impurities to the solution. Ahnstrom and Ehrenstein (Ah-59) found that light

intensity could be increased by the addition of peroxides to the solutions, such as hydrogen peroxide, benzoyl peroxide, or the ether dioxane.

They observed a ten-fold increase in luminescence intensity by this method.

1.4.3 Sample Factors . In the study on alkali halides (At-75) the LL

properties of different NaCl samples appear to depend on the origin of

the samples. For six samples of NaCl of different origin, light yields

differed by factors of up to five for a 100-rad dose. These differences

were attributed to differing amounts of impurities and differing heat

treatment histories. It was observed that pre-irradiation annealing

(600°C for 5 hours) or crushing enhanced the response. A study of preirradiation annealing of NaCl showed that although higher temperatures

improve sensitivity, they also result in increased fading of the lumi- nescence.

Klimentov (Kl-73) has measured light output vs. annealing temperature

for various solid polyhydroxy compounds. His curves, which are in terms

of percent maximum light yield vs. the ratio of annealing temperature to

the melting point of the hydroxy compound, show plateaus that rapidly

decrease to zero light yield within 15 percent of some critical temperature ratio that is different for each compound used.

The response of monosaccharides has been found to remain stable for

a period of seven months when the samples were stored at room temperature.

Samples of trehalose heated to 80°C for two hours after irradiation dis9
played no change in light output, and heating to 60°C for 60 hours gave

a decrease of only 18 percent (At-74b). On the other hand, in the amino

acid study (Et-77b), valine, typical of the amino acid group, was found

to have lost 20 percent of its response over a one-year period when stored

in a desiccator at room temperature. Bartlett (Ba-79) has found that for

the mannose-water system there is a loss of light yield of 10 percent for

the first six hours; thereafter the decay is slower, the response decreasing from 90 to 60 percent of the initial response in the ensuing 240 days.

These results were for doses around 4000 rad; however, Bartlett has found

that there is an enhancement of the response upon storage for doses

greater than the saturation dose (10^ rads)— a fact that is of theoretical

importance. Since there were no corresponding changes in electron spin resonance (ESR) absorption, Bartlett postulated that the local concentration of oxygen near the free radical sites in the irradiated mannose is

a determining factor in the LL response.

Atari et al . (At-73a) have indicated that particle size is an important factor affecting LL output for NaCl . In their work, they con- trolled particle size by sieving, although the actual sizes they used

are not indicated. Buchan and Ettinger (Bu-75) have shown a dependence

of light yield on the particle size for LL of xylose in water. Samples

studied ranged from about 50 to 350 ym in size, with light yields being

greatest for the larger particles. Bartlett (Ba-79), however, using a mannose-water system, displays curves for two different particle sizes

with median diameters of 68 and 120 pm which indicate that the smaller

size produces higher photon yield. Kannan (Ka-79), who used a mannosewater system and covered a dose range of 4x1 0^ to 7x10^ rads, found improved reproducibility of LL output by using grain sizes from 75 to 180 pm

and pre-irradiation annealing at 45°C. In this experiment there was no significant fading of the LL signal for mannose in 72 hours, but for a similar glucose-water system a 41-percent fading occurred in 25 hours.

The mannose response faded by 13 percent after 213 hours.

10
Humidity is an important factor when the materials are hygroscopic.

Atari and Ettinger (At-73b) found that samples of glucose, xylose, and

mannose stored 16 hours in a relative humidity of 60 percent, lost 20

percent, 40 percent, and 50 percent, respectively, of their luminescence.

For most saccharides, exposure to daylight for 48 hours, or to a tungsten lamp, had no effect on the response (At-73b). For trehalose

dihydrate, exposure to direct sunlight for a period of 5 hours produced

a loss of 10 percent in light yield. Exposure to UV gave an increase in

LL output for the saccharides (At-73b). A similar situation was observed

by Ettinger et al. (Et-77b) for proteins and nucleic acids. When these

materials were exposed to a broad spectrum of UV radiation in the range

of 180 to 370 nm, the light emitted on dissolution was found to be proportional to the energy fluence of the UV. Proteins are also reported

to be sensitive to the UV component of daylight. Bleaching by visible

light was observed in pepsin but not in trypsin.

The temperature at which dissolution takes place is reported by

Atari et al. (At-73b; Et-77a; Et-77c) to have a marked effect on the

light yield. The decrease in yield is of the order of 2 to 4 percent

per °C in the temperature range from 6°C to 60°C.

The fact that impurities in the sample can affect light emission

during dissolution was considered by Atari and Ettinger (At-75). In

their studies with alkali halides they found large differences in light

yields due to the effect of impurities. They indicate that the most

common impurities for the alkali halides are OH", Cu^ and O2 ” ions. Of

these, they found the Cu^ ion to have the greatest effect, with light

emission enhancement of more than one order of magnitude resulting from

dissolving the NaCl powder in water containing a 10"^ M concentration of

Cu^. Klimentov (Kl-73) has measured various LL responses in the presence

of free radical scavengers. The most notable results are that the

hydroxy compounds-luminol system is unaffected by the presence of

transition-metal salts (Cu"^^, Ni'^^, Fe'’'^), whereas 3-naphthol , hydro11
quinone, sodium iodide, sodium sulfite and sodium nitrite all reduce the

light yield of the following compounds: etriol, pentaerythritol and

xylitol

.

In reference to impurities of sugars, the author was able to purchase

from Baker Chemical Co. sucrose and lactose that had an order of magnitude

less trace metal impurities than reagent-grade chemicals, and attempted

a LL study coupling these with luminol passed through a chelating resin.

These substances produced unaccountably high backgrounds for the low

doses ('^'l rad) that are of greatest interest. Takovar obtained a similar

result for reducing sugars and pure water (see Et-82a). The most successful combination appears to be the non-reducing sugar trehalose and

luminol, which can be read out at the 1-rad level. However, "trehalose

ultrapure" is not available commercially.

1 .5 Luminol Chemiluminescence Assays and the Application to Lyolumi- nescence

There are well-established procedures (Mc-73, Bo-75, Sh-77) to handle

the luminol -generated chemiluminescence assays of trace metals (Co(II),

Cu(II), Fe(II)) and of compounds such as hemin and vitamin B 12 containing

iron and cobalt, respectively, as the central atoms. Trace analysis

using the metal -luminol system is based on the metal ions' ability to

promote the hydrogen peroxide oxidation of luminol in basic aqueous

solution to produce chemiluminescence (CL). In the presence of excess

luminol and hydrogen peroxide, CL intensity is proportional to the limiting concentration of the metal ion present. Usually the metal ion will

possess oxidation states requiring a one-electron transfer that aids in

the peroxide reaction with luminol to form an excited aminophthalate

anion, which then returns to the ground state emitting a photon (Bo-75).

Luminol has also been used to measure the production of H 2 O2 which specifically assays the concentration of blood glucose when it is enzymatically oxidized (Bo-75, Se-78). Other known luminol reactions are

the hydrogen peroxide enhancement of the oxidation of luminol by the

12
superoxide radical (O2 ) (Sc>76) and the luminol enhancement of LL in

saccharides. These may be related since there is evidence that superoxide radicals are generated when dry saccharides are irradiated (At-74b).

There are several mechanisms proposed for the LL effect in saccharides (Et-82); the correct one must enable one to explain both LL as such

and its enhancement by luminol, i.e., the activation of luminol chemiluminescence by the radiolytically-produced and subsequently trapped free

radicals stemming from the saccharides. Baxendale (Ba-73) has proposed a mechanism for luminol interacting with free radicals formed in aqueous

solution during pulse radiolysis. For the luminol-amplified LL, the

mechanism would probably involve decomposition of hydroperoxides which

could provide the hydroxyl radicals needed in Baxendale's mechanism.

Ettinger and co-workers (Et-77c) used luminol to increase the sensitivity of their LL system. It would appear that luminol -enhanced LL is

based on the presence in the solvent of excesses of luminol and dissolved

oxygen as compared to the limited number of free radicals liberated upon

dissolution of the organic solid under investigation. The resulting CL

intensity should be proportional to the concentration of free radicals

trapped in the organic solid irradiated. The limiting aspects to this

system will be the amount of trace metal impurities in the reagents and

the autoxidation which causes free radicals to be formed in the organic

solids used, even in the absence of ionizing radiation.

1 .6 Lyoluminescence Readers

LL can be quantitated using a photomultiplier (PM) tube and the

associated electronics for the luminescence readout. The LL detection

method used by the British researchers (At-73a) is a relatively simple

one. A borosilicate glass cell containing the solvent is placed above

the window of a PM tube inside a light-tight box. The irradiated samples

are added to the cell by remote control and stirred automatically. The

signal from the PM tube is fed to a DC amplifier and from there to a

13
voltage- to-frequency converter and scaler. The light yields are recorded

as number of counts per unit sample weight. The amount of sample used

varied between 2 and 15 mg depending on the sample material; when water

was the solvent, the volume used was 5 ml.

The shape of the light decay curve indicates the presence of two or more diffusion controlled LL reactions diffp-' m time scale. Because

of its greater intensity and direct re^ to dose, only the shortlived peak, which appears to have two components, was measured. The

light intensity was found to peak in approximately 0.1 second and then

to die off, at first quickly and then more gradually. For this reason

the light output was integrated over a 3-second period (At-73a; At-74a).

In an alternate readout method used by Puite (Pu-77; Pu-82), a glass cup covered with a light-tight rubber membrane and containing 15 mg

of the sample was placed above the closed shutter of a PM tube. After

the shutter was opened, 4 ml of distilled water were injected through

the membrane. In this method the light output was integrated over 10

seconds.

An improvement in the sensitivity of the readout system is possible

by the use of a liquid scintillation counter (LSC) which has two PM

tubes, and therefore, an almost 4-tt counting geometry, and automatic

temperature control, down to 6°C for the Packard Model 3320 "Tricarb",

Packard Instrument Co., Downers Grove, IL* (Zi-78; Ha-80). The temperature control is useful in stabilizing (and at low temperature reducing)

the "self-glow" or chemical background of the luminol (Et-82).

There are well established procedures (St-69; Sc-70; Go-79) to

handle the luciferin-luciferase-generated chemiluminescent assay of

*Throughout this paper, commercial product identification does not imply

a recommendation or endorsement by the authors or their institutions, nor

does it imply that they consider the identified product to be the best

available for the purpose.

14
adenosine triphosphate (ATP) using a liquid scintillation counter as a single-photon counter. Also, there is wide use of LSC in health physics

establishments and the conversion of one to an LL reader (if the system

becomes sensitive enough for personnel dosimetry) may be far cheaper

than building or buying an ATP photometer.

It should also be noted that (1) the author has compared SAI Technology ATP Photometer Model 3000 with a Packard LSC Model 2002 and found

preliminary results indicating that for a tritium check source, the LSC

gave one hundred times the counts for a number of one-minute counts; and

that (2) Ettinger (private communication) has stated that Packard appears

to make the most sensitive chemiluminescence photometer.

2. SYSTEM AND PROCEDURES CHOSEN FOR THIS WORK

2.1 System Chosen

The system chosen for this work was similar to that used earlier by

the author (Ha-80). It consisted of an LSC at an operating temperature

of 6°C, counting electronics, and a pre-cooled sample-delivery assembly,

in which capsules filled with about 10 mg of the sugar under investigation were emptied into modified LSC vials, each containing 2 ml of an aqueous luminol solution of suitable concentration. The Packard LSC has

a six-second delay in counting, for moving the sample-delivery assembly

down a shaft and placing it into a shielded counting chamber. In order

to allow for this delay and to be able to record the entire LL emission,

the sample-delivery assembly incorporated a small modified timer system

(Tatone "1/2 A Tick Off" model airplane fuel shut-off timer, Tatone Products, San Francisco, CA) which supported the sample capsule and dumped

its contents after the assembly had entered the counting chamber. Fig- ure 1 shows the assembly in the chamber.

All the counting electronics used in the present application were

external to the LSC (see the block diagram. Figure 2). However, an NBS15
constructed electronic splitter (not shown In Figure 2) enabled a user

to switch easily back to normal Instrument operation.

Single-photon-resolution RCA 8850 PM tubes were employed, operating

at a nominal 2650 V, with a maximum response at X = 390 nm, which Is

well within the range of the luminol-ampl if led LL response of X = 424 nm.

2.2 System Setup and Calibration

Throughout any given experiment, a scintillator source of in

PPO-toluene was used to calibrate the system and select a discriminator

level suited for luminol-sensitized LL readout. A pulse-height spectrum

was taken for (Figure 3a) and was visually compared with a published

pulse-height distribution of a ^^Fe nearly-monoenergetic electron and

photon source (Ho-73), in order to check out the system. Figure 3b is

a pulse-height distribution obtained with both PM tubes, after they

had been brought in "register", i.e., after their individual amplifier

and voltage settings (« 2650 V) had been adjusted to line up the various

spectrum peaks in order to make the discriminator level the same for

both tubes.

The reason for the choice of in PPO-toluene for calibration purposes lies in the similarity of the pulse-height spectra of in PPOtoluene and luminol. Figure 4 shows a comparison between these pulseheight spectra (luminol light emission in the steady state). Luminol,

in reasonable concentrations (lO"^ M), is a single-photon emitter with

respect to the resolving time of the system and, as such, produces a single photon peak. For very high light outputs which might result from

luminol-enhanced LL, distortions in the pulse-height spectrum due to

pulse pile-up would cause multiple peaks, just as those shown in Figure 3

for the beta-emitting in the liquid scintillator, in which bursts of

photons resulting from beta-particle absorption in the scintillator

causes double and higher-order photopeaks. While, in principle, it is

possible to correct for spectral distortion (He-65, Ha-80), it is preferable to avoid pulse pile-up altogether when one desires to obtain light

16
intensity as a function of time. In the experiments described in this

paper, counting rates as a rule were kept below 80,000/s.* The last

part of the calibration was concerned with setting the discriminator level

just below the single-photon peak. Once that level was chosen, it was

kept through all experiments. Each time the system was used, the first

non-zero channel and the single-photon peak height were checked. Also

measured was the signal-to-noise ratio in the single-photon peak of

in the liquid scintillator; this ratio was found to be 10 to 1 and was expected to be at least as high for the luminol -enhanced LL.

It should be noted that a considerable improvement in geometry

could still be made by introducing aluminum reflectors about the sample.

In the present geometry (Figure 5a) the counting efficiency for a quenched source**, which fairly well resembles a chemiluminescent

source, was measured to be 11.5 percent, whereas the geometry in

Figure 5b from an identical LSC setup with photomultipliers of almost

identical characteristics produced a 19.4-percent efficiency.

2.3 Preparation of Readout Solutions and Samples

All glassware and plastic items are acid-washed (10% nitric acid)

and rinsed with deionized water (purified using a Millipore system).

Luminol (Eastman Kodak) solutions are prepared in 0.1 N Na 2 C03 (Baker)

at a pH of 11. This is close to the optimum pH (Et-82a). The concen- tration of the luminol is adjusted based on the dose to be administered

*Measurements with pulses from a pulse generator, shaped similarly to the

pulses from luminol (total pulse width of 2 ys, equal rise and fall times

of 0.5 ys) established that at a counting rate of 500,000/s the system

exhibited a 4-percent counting loss. Taking into account that the pulses

from the luminol would be random, it was decided to reject measurements

resulting in a counting rate higher than one-third of this rate, in order

to allow for pulse sorting. As a rule, the counting rate, in fact, was

kept to within one-sixth this number, i.e., to within ^^^80, 000/s.

**The ^H source in PPO-toluene used as a check source during the experiments had no additional quencher added. It was counted with a 73.3-

percent efficiency (summing the response of the PM tubes).

17
to the sample in order to avoid saturation of the electronics. For

doses less than or approximately equal to 1 rad, 5 rads and 10 rads

from a y-ray source, concentrations of 3.6 x 10“‘+M, 1.8 x lO"*^!^,

and 9 x 10"^M, respectively, are used. Two milliliters of the solution

are pipetted into the liquid-scintillation vials, sealed and refrigerated at 6°C for at least two days to allow them to come to equilbrium.

The temperature was selected to lower the " -glow" of the luminol

when it is used in the LSC which is a'l.i. ut 6°C.

Acid-washed glass beads (w 500 ym in diameter) are placed at the

bottom, and then a weighed sample (a 10 mg) is placed on top of the

beads inside the capsule and stoppered (see Fig. 1). The glass beads are used to help disperse the sample as it contacts the solution.

The capsules are given the appropriate radiation doses. (Some are left unirradiated and used as controls.) Each capsule is then opened,

placed into its individual small plastic container with a dessicant,

and left over night. Subsequently, the capsules are refrigerated to

6°C.

The readout of the samples is performed with dark-room illumination

to avoid large self-glow of the luminol solutions as each vial is transferred from the refrigerator to the LSC and its contents poured one at a time into one of the LSC vials containing the luminol solution, using

the timer-dumper (see Fig. 1). Readout of the LL is accomplished using

the LSC in the manual mode. Prior to each readout, the system is checked

with a source and then the multichannel analyzer (MCA) is set at 0.1

s/channel. A typical LL "glow-curve" (counts vs. time) is shown in

Fig. 6. A fixed number of channels is summed and used throughout the

experiment to represent the response corresponding to a certain dose.

Some of the curves are found to have more than one peak, probably due to

mixing problems; in this case, suitable alternate starting and stopping

points are chosen for obtaining the sum of the region of interest for

all curves of the particular experiment.

18
3. BRIEF SUMMARY OF EXPERIMENTS PERFORMED

The following is a brief summary of the experiments performed and,

where appropriate, mention is made of any difference in the procedure

from that stated in Section 2.

3.1. Advantages and Disadvantages of Using Low-Temperature Readout

The self-glow of luminol was measured at room temperature and at

6°C. At the lower temperature, the self-glow was lower by a factor of

10 than at room temperature. This means that the luminescence peak rides

on a much lower baseline and increases the range of doses that can be

assayed at a given luminol concentration; also, the larger signal-tonoise (self-glow) ratio that ensues makes noise subtraction less of an influence on accuracy. However, the lower temperature seems to cause more samples to lose their signal (fade). This may be due to high humidity conditions at readout, even though the samples are initially dessicated. It takes about 25 seconds to transfer the sample from the

refrigerator to the timer-dumper and then into the LSC; during this time

water condensation may occur. An exhaustive set of tests would have to

be performed to determine the cause of fading.

3.2. Effect of Luminol

The sensitivity of the system without luminol was measured. ®°Co

y-ray doses of 50, 150, 450 and 1350 rads were given to samples of trehalose di hydrate. The solution was 0.1 N Na 2 C03 . If other buffers are used, it should be made certain that they are not free-radical scavengers.

Figure 7 is a curve of response-vs-absorbed dose to water (briefly re- ferred to as dose) for this experiment. There are three replicates for

each point showing relative standard deviations of up to 25 percent from

the mean. The lowest dose administered (50 rad) was seen not to produce

a response significantly different from background.

19
The system was then used with luminol at a concentration of 4.0 x

a pH of 10.88, a temperature of 4°C, and a sample weight of approximately 14 mg. The doses to trehalose samples were 0.15, 0.30, 0.60 and

1.20 rads of ^°Co y-^^ays. Figure 8 shows the corresponding response-vsdose curve. There were three replicates per point and the average relative

standard deviation from the mean was 35 percent. The three lowest doses were not significantly different from background. The luminol improved the

sensitivity by a factor of 100; however, the reproducibility was poorer.

In this experiment, purified luminol was used (see discussion in the next

section). Whether the luminol was purified or not made no difference in

reproducibility. EDTA, a chelating agent for trace metals, was also used;

it had no effect.

3.3 Influences of Increased Reagent Purity

Luminol was passed through a column containing Chelex 100 (BioRad)

(mesh 200-400 sodium form), at a pH of 8 in order to take out trace

metals that might contribute to self-glow. The pH was adjusted back to

11 with Na2 C03 (Baker-Ul trex grade). The concentration of luminol was measured on a Cary spectrophotometer (X = 347 ym, e = 7680M"i), and

adjusted to 4.0 x lO’^^M. The process lowered the self-glow by 25 percent.

Compared to the temperature effect and labor involved, it was deemed

unnecessary to repeat the luminol purification process for each experiment.

However, an experiment was designed to use very pure sugar samples with

the purified luminol. J. T. Baker Chemical Company produces a grade of

reagents called Ultrex, having one-tenth the amount of trace metals such

as Ni, Co, Fe, as compared to "reagent grade" chemicals. The trace

metals could be one reason for high background. The only disaccharides

that can be purchased at this purity were lactose and sucrose. Unfortunately, they produced a background that was very much higher than that

of trehalose (non-reagent grade purity). The high background does not seem to depend on whether the sugar is a reducing sugar or non-reducing

one. (Lactose is a reducing sugar and trehalose and sucrose are not.)

20
3.4. Baseline Data for Different Detector Compounds

A number of compounds other than di saccharide were tried. A car- bonic acid derivative mentioned earlier and NH4CI were chosen for their

hydrogen content, which could be useful for neutron dosimetry. They

gave no meaningful response. Stearic acid was assayed, because it was thought that perhaps a long-chain molecule might hold trapped free

radicals further apart as compared to other compounds and retard freeradical recombination. It produced a signal-to-background ratio of 2:1

at the 0.1-rad level in an aqueous solution of luminol and 10 percent

alcohol. The relative standard deviation from the mean of the signal

for identically exposed samples was 85 percent. The mixture of water

and alcohol leaves the measurement of pH somewhat ambiguous. Also there

may have been age problems associated with the luminol. This experiment

needs to be repeated.

Deoxy-D-ribose was tried as a lyoluminescence phosphor because it

has a G-value of 650 per 100 eV (So-74). The relationship between G-value

and lyoluminescence is one that should be explored. The doses were

0.15, 0.30, 0.60, and 1.20 rad. For this compound no meaningful area of

the glow curve could be defined; the light output reached a peak that

was maintained for over twenty-four seconds. Figure 9 is a response-vsdose curve for the area in the vicinity of maximum peak height. The

electronics of the system was very close to saturation for the last

three doses. The 0.3-rad level is significantly above background; however, the 0.15-rad level is not. There are three replicates per point,

and the experimental parameters are the same as described for the

trehalose- luminol experiment.

The last set of compounds examined, mainly for future experiments

involving dopants, were dextrose, fructose and vitamin C (which has a structure similar to a monosaccharide). Dextrose produced a high background and fructose gave poor reproducibility (relative standard deviation of 60% at a 1.2-rad level). Figure 10 is a response-vs-dose curve

21
for vitamin C in luminol. The largest relative standard deviation is

25 percent, but only the 1.2-rad dose produced a response significantly

above background. There are three replicates per point, and the experimental parameters are the same as described for the trehalose-1 uminol

experiment.

3.5. Attempts to Improve Reproducibility

These experiments involved mechanical mixing, and sample-mass and

baseline corrections to the observed response. The MCA was interfaced

to a Tektronix microcomputer. Model 4051. Sample-mass and luminol

baseline (self-glow) corrections could be made to the peak areas. Four

treatments were tried: no mixing (the standard method described earlier),

mixing with a paddle hooked onto the timer-dumper, pre-stirring of the

luminol for aeration, and pre-stirring and mixing. Unfortunately the

mixing with a paddle was mechanically unreliable (it would not always

start) but there were strong trends toward improved signal -to-background

ratio. The analysis is complicated because there are four treatments

and two corrections (mass and baseline subtraction). For the "no mixing"

case, mass and baseline corrections optimized the combination of signal

to-background ratio and reproducibility. For all other cases, some sort

of mechanical mixing improved the signal -to-background ratio as compared

to "no mixing" by 20 to 400 percent. However, after corrections were

made, no treatment had necessarily any clear-cut better reproducibility.

Baugh et al . (Ba-77) point out that, in mannose, lyoluminescence (per mg)

increased non-linearly with mass of the irradiated sample up to 13 mg

and then increased more gradually up to 18 mg. It can be postulated that

just weighing the samples is not enough; the range of masses must be kept

very small. This will need further verification. To implement some of the

trends found in the mixing experiments would call for a major modification

or a completely new system. This point will be addressed later.

22
3.6. Use of Dopants

The sensitivity of lyoluminescence is dependent on the number of

free radicals trapped in the matrix of the solid. The problem of enhancement of LL has been addressed by a number of authors (Bu-77, Ch-79,

Bar-79, Et-81). In the present study, a different approach was used.

The author investigated a solid's ability to trap radiolyticallyproduced free radicals by increasing the number of lattice defects in

the material. A simple method of introducing suitable dopants to the

material (in this case, trehalose) was to prepare solutions that were

subjected to large doses of radiation, then to recrystal ize the material

containing the radiation products as the dopants; and finally to isolate

the product which might be responsible for any enhancement effect. In

spite of poor reproducibility, a definite trend towards enhancement can

be reported. Since the poor reproducibility may be due mainly to inadequate mechanical interfacing, this method should be pursued.

Sample preparation involved irradiating three 1-M solutions of trehalose with ^^Co Y-'^acliation at a dose rate of M3 krads/min to levels

of 32, 96, and 288 krads, respectively. (A fourth solution remained un- irradiated for use as a control.) The major irradiation product is

glucose and, although the conditions of irradiation (concentration and

ambient atmosphere) were different from the work of Adam. (Ad-77), his

value for glucose formation from trehalose (G = 2.3/100 eV) was used.

Using this value in the formula (Dr-71):

Concentration (moles/liter) = G«D(rads) *1 .037 x 10"^ ,

with the above doses, gives 78, 234, and 702 parts per million (ppm) of

glucose formed. Solutions of trehalose doped with 235 and 700 ppm glucose were prepared; also, for comparison with an inorganic dopant, solutions of trehalose were doped with NaCl to the same levels as above. All

samples were kept in an oven at 45°C for four days, then placed in a refrigerator at 6°C until they crystallized. Of the samples irradiated

23
in the kilorad range (doped by radiation), those given higher doses crystallized first, whereas the opposite was true for the chemically-doped

solutions. All samples were chopped up, dried at 45°C for one hour, and

sifted to a particle size of less than 250 vim in an acid-washed plastic

sieve (Nalgene). (The plastic sieve is used to avoid metal contamination

to the luminol solutions.) The samples were irradiated with ®°Co yradiation at levels of 1, 5, or 10 rads at a rate of 'v>68 rad/h. The

luminol concentration was 9.0 x 10"^ M in 0.1 N Na 2 C03 . The MCA was set

at 0.1 s/channel.

Figure 11 is a graph of enhancement factor versus sensitizing dose.

The enhancement factor can be defined for a fixed concentration of luminol

as the ratio of signal-to-background of the sensitized sample divided by

the ratio of signal-to-background of the unsensitized sample. (Background

here is defined as the signal of the undosed sample.) The concentration

of luminol was chosen so that the signal from an unsensitized sample

exposed to 10 rad would be different from its background signal; in this

case, the signal-to-background ratio for the unsensitized sample was 1.2.

Figure 12 is a graph of the enhancement factor versus dopant con- centration, with the 5-rad curve of Fig. 11 being repeated for comparison.

The concentration of glucose is approximately equal to the amount that is

created by the sensitizing radiation. For a comparison of the action of

organic and inorganic dopants, the NaCl concentration was chosen equal to

the glucose concentration. In both figures, there are four replicates per

point, with the other experimental parameters being the same as in Section

3.4. The relative standard deviation of the un-normal i zed data is between

20 and 50 percent. The exact shapes of the curves can only be estimated.

The sensitizing radiation appears to increase the signal considerably,

while only slightly increasing the background. However, whereas the en- hancement due to the chemical dopants appears to lower the background

considerably, the signal remains essentially the same. Therefore, it

would appear that some product other than glucose in the radiation sensi24
tization process is causing the enhancement. The next logical step would

be to try chemical dopants in the sample or the trace chemicals mixed with

the luminol, in order to lower the background, and to try radiation sensitization of the sample in order to increase the signal.

4. REACTION MODEL

Finally, it should be noted that a glow-curve fit was accomplished

for LL without enhancement using Marquardt's nonlinear least-square

technique (Be-69). The curve-fit assumes a two-component (fast and slow)

exponential decay of light multiplied by a first-order buildup term for

the dissolving factor, in the form of

counts/channel = Cx + Cse'^^^lEl - C2 > C4.

By neglecting the very first point in the curve (the 100-ms flash of light

mentioned earlier) and cubing the buildup factor term, it was possible to

achieve a chi square of '\^2 . For six spectra (three dosed to a 1-rad level

and three unirradiated), all constants except C3 agreed to within 20 percent, C3 being the ratio of the slow component to the fast component at

t = 0. C3 decreases with an increase in dose, but at the 1-rad level

this trend is not significant. C2 and C4 may be related to the kinetics

of the system, however, a diffusion model and the work of Baxendale (Ba-73)

should be taken into consideration for a complete understanding of the

system. In this particular case, values of C2/C4 « 10 and C5/C2 « 3.5

were obtained. For the case of no luminol (just LL), the values were

C2/C4 « 60 and C5/C2 « 7.5. It appears that, since the curve fits simultaneously two processes (irradiated and unirradiated luminol -enhanced LL)

with five constants, there are only three degrees of freedom. Curvefitting was also planned for the data from the enhancement experiments

to see if there were any shape changes due to added dopants; however,

lack of reproducibility in the shape of the glow curve due to mixing

problems made this unattainable.

25
5. CONCLUSIONS AND RECOMMENDATIONS

Radiation sensitization and the use of dopants seem to improve the

sensitivity of lyoluminescence in the presence of luminol. It also

appears that solutions ought to be well aerated, in order to eliminate

oxygen mixing effects that take place at the liquid-solid interface and

lead to high backgrounds and poor reproducibility. The two effects

(mixing and sensitization) are independent in their increase of signalto-background ratios (a factor of 4 for mixing and a factor of 8 for

sensitization), and could combine to produce an overall increase of

signal-to-background ratio by a factor of 32 at the 10 rad level. This means that even without optimizing the conditions, doses as low as 0.31 rad could be measured.

Reproducibility of the results, to date, has been poor. However,

higher signal-to-background ratios and improved reproducibility may be

achieved with a new readout system. The author proposes one in which

the sugar is kept in a suspension of acetone which will not dissolve the

sugar. Then, as the suspension is mixed, a well -aerated low-temperature

aqueous luminol solution is infused into the system. The dissolution

would be slowed down, and perhaps made more reproducible. In a continuous

flow system the possibility exists for using much larger samples, and

this would increase the sensitivity of the method.

This work was partly performed while the author was the recipient of

a National Research Council fellowship at the National Bureau of Standards.

The author wishes to thank M. Ehrlich, C. Soares, B. Coursey, R. Johnson,

C. Dick, K. Eggert and H. Gerstenberg for helpful discussions and technical

aid.

26
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Phosphor." Int. Symp. Biomed. Dosimetry, IAEA, Paris (1980).

Et-81 Ettinger, K. V. and Anunuso, C. "Enhancement of Lyoluminescence

by Energy Transfer to Rare Earth Ions." I.J.A.R.I. 673

(1981).

Et-82 To be published in I.J.A.R.I.

Et-82a Ettinger, K. V. and Puite, K. J. "Lyoluminescence Dosimetry,

Part I: Principles." I.J.A.R.I. 1115 (1982).

Go-79 Gorus, F. and Schram, E. "Applications of Bio- and Chemilumi- nescence in the Clinical Laboratory." Clin. Chem. 2^, No. 4,

512 (1979).

Ha-80 Hanig, R. Thesis: "The Application of Liquid Scintillation

Counting Methods in Lyoluminescence Dosimetry." Purdue

University (1980).

He-65 Herberg, R. "Channels Ratio Method of Quenched Correction in

Liquid Scintillation Counting," in the Packard Technical

Bulletin, No. 15, Dec. 1965. Packard Instrument Company, Inc.,

2200 Warrenville Rd., Downers Grove, IL 60515.

30
He-70 Hercules, D. M. "Physical Basis of Chemiluminescence," in

The Current Status of Liquid Scintillation Counting , E. D. Bransome, Jr., Ed., Grune & Stratton, New York, pp. 315-

336 (1970).

Ho-73 Houtermans, H. "Probability of Non-Detection in Liquid Scintillation Counting." Nucl. Instr. & Methods 112 , 121-130 (1973).

Ka-79 Kannan, A. "Lyoluminescence Studies with a Photon Counting

System." I.J.A.R.I. 258-260 (1979).

Kl-73 Klimentov, A., and Mikhal 'chenko, G. "Investigation of the

Radiolysis of Solid Organic Hydroxy Compounds." Khimiya

Vysokikh Energii _7, 513-518 (1973). Translated by Consultants

Bureau, a division of Plenum Publishing Corporation (1974),

227 West 17th Street, New York, NY 10011.

La-79 Laflin, P. and Baugh, B. J. J. Chem. Soc. Chem. Commun. (1979)

239. [A colloidal suspension of sodium lauryl sulphate with

di phenyl isobenzofuran (DPBF) in water was prepared as a solvent for mannose. Enhancement by a factor of 10 was gained.]

Lo-61 Lofroth, G. "Yields in the Radiation Degradation of Solid

Carbohydrates." Acta. Chem. Scand. 1997-2006 (1967).

Ma-73 Mantaka-Marketou, A. E., Marketos, D. G., Rakintzis, N. Th.,

Vassilopoulos, G., and Nikokavouras , J. "Luminol Chemiluminescence Induced by Internal Irradiation, Gamma-Radiolysis."

Zeitschrift fiir Physikalische Chemie Neue Folge 8^, 106-112

(1973).

Mc-73 McCapra, F. "Chemiluminescence of Organic Compounds," in

Progress in Organic Chemistry 8, 231-277 (1973).

31
Pu-77 Puite, K. and Crebolder, D. "Lyolumlnescence Dosimetry in

Photon and Fast Neutron Beams." Phys. Med. Biol. 1136

(1977).

Pu-82 Puite (Part II). (See Et-82)

Sc-70 Schram, E. "Use of Scintillation Counters for Bioluminescence

Assay of Adenosine Triphosphate (ATP)," in The Current Status

of Liquid Scintillation Counting , E. D. Bransome, Jr., Ed.,

Grune & Stratton, New York, pp. 129-133 (1970).

Sc-76 Schram, E., Demuylder, F., DeRycker, J. and Roosens, H. "On

the Use of Liquid Scintillation Counters for Chemiluminescence

Assays in Biochemistry," in Liquid Scintillation Science and

Technology , A. A. Noujaim, C. Ediss, and L. I. Weibe, Eds.,

Academic Press, Inc., New York, pp. 243-254 (1976).

Se-78 Seitz, W. "Chemiluminescence Detection of Enzymically Generated Peroxide," in Methods of Enzymology, Vol . LVII: Biolumi- nescence and Chemiluminescence , Marlene A. Deluca, Ed.,

Academic Press, New York, pp. 445-462 (1978).

Sh-77 Sheehan, R. L. and Hercules, D. M. "Analytical Study of Chemiluminescence from the Vitamin B-12-Luminol System." Anal. Chem.

446 (1977).

Si-76 Simmons, J. and Bewley, D. "The Relative Effectiveness of

Fast Neutrons in Creating Stable Free Radicals." Rad. Res.

65 , 197 (1976).

So-74 Von Sonntag, C., Neuwald, K. and Dizdaroglu, M. "Radiation

Chemistry of DNA Model Compounds." Rad. Res. 1 (1974).

32
St-69 Stanley, P. E. and Williams, S. G. "Use of the Liquid Scintillation Spectrometer for Determining Adenosine Triphosphate by

the Luciferase Enzyme." Anal. Biochem. 381-392 (1969).

Th-76 Thwaites, D. I., Buchan, G., Ettinger, K. V., Mallard, J. R. and Takavar, A. "A New Sensitive Technique for the Study of

Radiation Effects in Amino Acids." I.J.A.R.I. 27^, 663-664

(1976).

We-60 Westermark, T. and Grapengiesser , B. "Observations of the

Emission of Light on Dissolution of Irradiated Solids in

Certain Liquids." Nature 188 , 395-396 (1960).

Wh-63a White, E. H., Zafiriou, 0., Kagi , H. H. and Hill, J.H.M.

"Chemiluminescense of Luminol: The Chemical Reaction." J. Am.

Chem. Soc. 86, 940-941 (1963).

Wh-63b White, E. H. and Bursey, M. M. "Chemiluminescence of Luminol

and Related Hydrazides: The Light Emission Step." J. Am.

Chem. Soc. 86, 941-942 (1963).

Wi-76 Williams, 0., Huff, G. and Seitz, W. "Evaluation of Peroxyohalate Chemiluminescence for Determination of Enzyme Generated

Peroxide." Anal. Chem. 1003 (1976).

Zi-78 Ziemer, P., Hanig, R. and Fayerman, L. "A Review of Lyoluminescence Dosimetry and a New Readout Method Using Liquid Scintillation Techniques," in Proceedings of the Health Physics Society

11th Midyear Topical Symposium on Radiation Instrumentation,

W. Wadman, Ed. (1978).

33
Summary

of

the

Properties

of

Lyoluminescence

Materials

Used

in

Studies

Appearing

in

the

Literature

O I T3 ^

(U d) T3 S- OI r—

lO to

C (O c_> o c o (T3 CT. CD o 1 i. to CO o fO TD o > 3 <u CO o 1 Q. c O r—^ O -t-> i- 03 10 o to o U- CO JD to s- CL z o

0) 0)

O 03 to &- to

L.M

C o o O 0) 03 CO "O o S- (U (U <T3 O 03 to c S- •o 03 dl z to « o s- (U i- r— •r" 4-> dJ <D to Q. (O 5 E to r— O +J w* W a c -a O 3 -)-> co .c CO JD <LI c r— CO 3

s- O' O)

O +J

O •—

3 a. (U o to 4-> _l S- Cl. to .o r— •r~ t— (>0 t/3 1/) o to

Co•1“ 4J -K fO O) T3

I- (/) rO

=3

O S-

-)->

Q

(O OO

LT) o

cr o (/» OJ c

•rO

T3 S- 3 -»-> 3 » in d) ?- ^ 

c ?- >-

d; -o

O) S- 03 lO c o s- 00 o 00

03 #»—

o O q: ... r— r—

?*“

X

(U 1 X

X

to to tD C' to o c o CVJ o evj Q O o

+J o +J o o o o

.c

M

m

O. Q. o Q. '— 3 r— 3

0) o E •r“ <u i4-> o

to r^— >1 •> .C

oo o o

O4-> Ci. E c 3

03 #. > s- S- 1— S- s- i- d3 d3 1— 03 d) 03 o +J 03 +J 4J -!-> 00 03 03 x: 03 03 03 3 3 4-> 3 3 3

03 • • d) (U 03 03 -o

(/) -o o o -o •r" <u •1“ •r* •r" s- r— “O s- t- i- S- o

03 •f— o o o o 3

•r"r

r** 1 S- <d J= .d .c tf-

<13 3: o o o u +J E

03 •r“ E / E E E 3

s: n-* 3 ' 3 3 3

fO •p- •r— •p“ -O ' T3 -o "O +J o O O O •r— 00 OO OO OO _l

(UOc

03

S- tn ' o

03 CO o o

03 to to 00 to

4- 1 1 1 1 1 03 03 +-> +-> 03 QC •=t 1 3 < < 3

34

*Saturation

dose

indicates

the

dose

for

which

response

isa

maximum,

with

subsequent

decrease

in

light

yield

at

higher

doses.
Dose

Range

Studied

Saturation

(photons-y;

or

neutrons-n)

Dose*

CO O) 3

0) OS 00 c c s- r—

CO

p o 0* •r“ a; o o o 1 .O lO S- s- S- S- S- S- i- Ol c +-> VA o ITS J- ITS ITS 10 lO fO lO fO o o • o • S- •r* 0) •5 0) (U 0) 0) O) (U c -o (U TS lO i/) E CO o s- c e O c c c c c c <u <u s- (U 4- 3 O o >0 (/) ITS o •r— • r- •r- •r* •r* •o •r- •r* o o VA s- fO JO •r“ > (U r— f— r— c T3 +-> T3 +J 0) o

(U »+- -o 4-> JO (U 3 3 c 3 CVJ +J T3 * 3 • lO. 4-> +-> O) cr o <T> (U CA o X S- X X X X X X Ol CO S- CO E fO z <T3 o c o o o ITS o o o o o o TS fO O) • • O) r— T3 •n" JO (/) s. (U CO s- i~ s- S- S- s- o O) o o s- c e 3 4-> M VA D. sz TO Q. CL £0. Q. CL Q-h- i/) c CO c os o o »> ITS 0) Q. ITS Ql CL Q. Q. CL a. LU r— •r“ r— lO > •r~ _i 4-> CO +-> E -o < _J s- eC =c c < <c < _J lO _i lO .c o +->

•o

<a

sT3

s- o

<u +J

</) 00

+Jc

O)

O)

(Jc

d)

s-<u

14-(U

u

«0

LOo

VOA

</) T3

»o

S- oX

00

<->iS J" .—

>- o .—

— cr» CD CD CD CD CD CD X o o <XI o O O O O 1— O r— r— f— ro o r-“ t— o o O o o o o O -*-> 4-> o +-> M 4-> 4-> •P o

4-> •p

in CO CO CO CO CO CO CSJ O O O O O O O O O o r“ r**“ 1

r— r— 1— r— r— I

CO > 3 s- S- s- s- s- s- s- s- t

4- o; <U 0) 0) O) <u 0) O) o r— +-> -p -p -p -p •p +J -p oo 3 lO fO lO lO lO lO lO lO OO 3 3 3 3 3 3 3 3

OJ T3

VO

lO 001 1 rv. 1 > 1 .c p < J— LU

JO1 -(-> LU

VOI

VO VOI o00

JO

s_<u +J

(A 0) 3 -t-> O <T3 O) s- 3 +-> CT-r- cC C

S- -o O) r— o • .

•r“ c

lO 3 (A o •r— r— -o lO C

s- 4- •r“ 10 OJ O) o>

(U

O o p— OS E E E

-p E < ns E •r- • r— lO 3 0) O) (U E 1

•r- E E E

21 o c c c 10 >> E lO lO ns .C c •r" -p E <U +J p P

-P r— 3 <U E 3 3 3

ea lO fO r— x: .E r— r— f—

_J > > > CJ3 Ol. t— o o o

JO

C\J 00I -»->

35

*Saturation

dose

indicates

the

dose

for

which

response

isa

maximum,

with

subsequent

decrease

in

light

yield

at

higher

doses.
Dose

Range

Studied

Saturation

(photons-y;

or

neutrons-n)

Dose*

X X

X

CM o

O o OJ P iA P CO S3 00 -o -O T3

i- (O i- ea p ra

(O 1- (0 P <tJ P

(U a; (U CID Ct/O Cro

•

1- o •1- o •

1- O

_J f— _j 1— _J r—

T3

fO

J-o

X

cn

o

•a

fO

s-

(U +J

(/) >1

</)

(Uo

c

(U

s-0)

l*-0)

^ > >-

IX>o o

IS)o

o o o

•»-> +J 4J

ro m 00 o o o

S)o

o

-4->

ooO

<S)O

o

-t-> mO

>-

IX> o

00O

IS)o

o

o

o

+J

onO

JD

I

LlI LU

r».

I

Si

I 4->

Si

I

Si

p>.

P>^

I

Si

I P

p^

I •pUJ

ix> o

op

(U> p p P p p p P P p

,

O) (U (U (U <u 0) 0) (U 0> o +J -p -p -p -p -p •P •P 4-> (S) <0 fO <TJ (O fO ro «o la 3 3 3 3 3 3 3 -S

O)c 1 •r" CO lO r— «

c f— O o • • (O CO O JZ •r" CO

•r“ u o £= >> Q. U (U P >0 o T3

<u +J o fO * . (U (U •r“ •p o o >> p CO i,

c 0) C a P OJ

<0 •r* p -p (U CO C fO lO z; .a Q. o 0) I, N lO CO •r“ (U .c o

0) p p O (O p Q. CO p— o p

-p P c >0 N CO .X (C3 >) Q. o o u

c P (U X C >» r— s: P OJ 3 fO 3

< 00 C5 o UJ _I < o. 1— Q. 00 00

(O

r>.

I p

UJ

36

We-60

Alginic

acid

Water

up

to2

x

10®

(y)

At-74a

Trehalose

Water

1

to

10®

(y)

10®

Linear

to

10®

rads

*Saturation

dose

indicates

the

dose

for

which

response

is

a

maximum,

with

subsequent

decrease

in

light

yield

at

higher

doses.
Dose

Range

Studied

Saturation

(photons-y;

or

neutrons-n)

Dose*

s- S- •1- -O 1— S- i- 1 (L) (O

fO (O E <U *1- (U (0 1 S- CO -t-> (U (U JB .f— +J (U 2 OJ •r~ O O CD c C ID +J -o c c C CD O u "O Q.T3 >1

•1— •r- -O •r- 3 -

1- 3 4-> •I- TD r— c O S-

</) r“ r— fO > O o 3 r— »0 (U (U >, S- O O -M

(U s- ID (D o O S- ^ CD o 4-> Q. +J •r-

« . • •a . T3 CD ^1— <u s •— o X XlD S- O T3 c <o E X CD S- fO cu CD >>— CO O

z: o o o fO <D *1— o (U (U o o D3 S_ c C f— fO o -o c

S- S- r— <U t— 3 •r- s- 4-> S- 1— Ol •P“ (U -t-> C U 0) TQ. Q. c <0 cr+J CD CL COO E +J <J O 3 N E

Q. Q. O •i“ *r- fO CD >> Q. O •I- o 3 c O) 1— •!- 3 < —

1

O r- r— lO CD eC -t-> _I f— C 4-> O r— 1—

o<TJ i- LDo

IDoIDo

,—

f s —

T3

<0 CD O S-

^

.i«—-N, O r—~ 00 o —'• >- r— — O r— X

X X

CD o CD X o ro cn O • fO o r—~ 1— r— CvJ

1

O o o

o -«-> +j o o O

o +J •4-> +J M 4-> m o o o • O o Q. o ' ' o Lf) CO 3 CVJ

<u E c

<L) o •r“ +J c r—

CD ^1— (O >1 E3 r— c to +J c

c CD c r— CO o

<u 3 a> O 3 •!- > O CT» c s- i- O +-» S_ i- r— (U •r“ •r— (U 0) <U 3 d) (U o 3 U E +J +J 3 r— 4J oo CT 3 3 »o (O o- O to to ct _J 3 3 C CO 3 3

<t3

s- OJ O) (U <u

OJ CO CD CD CD -M o o o o (U (LI (U

to p— p— Ol r— CD CO CO

to to to CO (O o o O O

JZ JC .c o JC tv o O U

0) <u OJ f— <U 3 3 3 3

S- S- s- >0 S- CVJ r— r— p“

t— h- 1— X »— • CD CD CD

<11 U

c

(U

s- to

"tO- oIX C» JO

CO

to X cn o <Ti Ol IX IX IX IX X LO CD X

M- 1 1 1 1 1 1 1 1 CU +J +J •r- •!-> +J x: <U x:

OH ca: LlJ M c LcJ < 3 CJ

37

*Saturation

dose

indicates

the

dose

for

which

response

is

a

maximum,

with

subsequent

decrease

in

light

yield

at

higher

doses.
Dose

Range

Studied

Saturation

(photons-y;

or

neutrons-n)

Dose*

1 to

cu i- to O r— (O o o cu to s_ > > o (U 5 o CU o cu > O) Q. (U 0) •1- -O C 00 O ro 1 > ro 1 >

•r- c s s (U +J q; •r- -a <o o (O o

to •M (U > S- •!- r— 03 CU o s- ^ o S- JO

Ol ro > a; o (O "D i- JD to +J CO. 03 +J Q. 03

4-> r— •r- s oo • O. 3 . u 3 T3 3 "O o <u +J (Ti . X m s- 03 s. to 0) s- to i- 03 i- z i- <J o •> CVJ (tJ to o o (O S- 03 03 i- 03 03 i- 03

QJ r— to •> i- 1— cu CU .> <D CU • •> QJ (U

<U C 0) TD o. to Q. C ro c "O C O C -O c O C

<4- O Z c 1— (O CL O o •r“ »o *1— o o •r* 1— Ol o +-* <o (O 5 < +-> 1. 1— ro S. f— ro _J

oro

i.

J-O

o

X

00

IT)o

'—c

to ro o O

>- X X 00 to O Lf) o Li'l CVJ n— r— o

o o o +J O +J 4-> +J o o +J cti CO o o O tn r— Lf) r— t—

O) +J

to>1

t/) +Jc

O)> S- s- S- S- r— cu cu cu cu cu o +J -»-> +J +J oo fO 03 03 03 03 3 3 3 3 3

1

o cu

03 c -M

•r- o 03

S- E C

cu

-l-> CU CU cu CU S- 03 to to to to >>

s: o cu o o o £0. o +-> c c c

3 03 c c c •r— 1— i. 03 03 03 _l O T3 s s: s: to

cuCJc

(U O JO 03 fO

s- 00 CO o cu 1 00

4- s- 1 1 1 1 CU 03 +-> -(-> 3 +J Od 00 ca: LU CO- UJ

38

*Saturation

dose

indicates

the

dose

for

which

response

is

a

maximum,

with

subsequent

decrease

in

light

yield

at

higher

doses.
Dose

Range

Studied

Saturation

(photons-y;

or

neutrons-n)

Dose* c

s- o

<0 SO) m +J

{A

O)

+->O

M

• O I— <u XX »o o O CM E c

S_ IT) E 0» CL O O) 3

CL

O l— < +-> E -»-> 4-

O

-o

fO

s0) +J

CO GO

4-> E

<LI >O

tn

(OE

Q)

+-> 03

OJUE

O)

s-01 4-

OJ a:

O)oE

O) CM 3 E

r—

O

4- E EO CO E •—I

+-> I 3 O

Qi F— E O

I— -l-> 03E^E I—'

(U I -E OE

CU

+-> 03

CU +J

03E

•r“E

>)

Q.

J3O00PUJ

39

*Saturation

dose

indicates

the

dose

for

which

response

isa

maximum,

with

subsequent

decrease

in

light

yield

at

higher

doses.
Table 2

Factors Affecting Lyolumlnescence Response

Solvent Factors References

Type At-73a, At-74a, At-75, Av-81 , Et-82,

La-79

pH Ah-59, At-74a, Et-77a, Bu-75, Ka-79,

Kl-73

Dissolved oxygen concentration At-73b, Ba-80, Er-62, Et-77a, Kl-73

Volume Et-77a, Et-82

Impurities

Sensitizer Factors

At-74b, Ka-79, Kl-73

Type At-74a, At-74b, Bu-77, Ch-79,

Et-77c, Et-82b

Concentration Et-77c, Kl-73

Impurities Ah-59

Particle size

Sample Factors

Ba-79, Bu-75, Ka-79

Puri ty At-75

Heat treatment history At-75, Kl-73

Storage temperature At-74b, Et-77b, Ka-79

Storage time after exposure At-74b, At-74b, Ba-79, Ka-79, Pu-77

Exposure to light At-73b, Et-77b

Exposure to humidity At-73b

Temperature at dissolution At-73b, Et-77a, Et-82

40
il

^U.S

GOVERNMENT

PRINTING

OFFICE

1982-37?

731
I>

i!

O< - -i oQ CO O

3Q S

COVItNMIllT

OfftCt

7]|
counts

per

channel

counts

per

channel

pulse height

Figure 3. pulse height spectra (linear scale) taken with

RCA 8850 PHOTOMULTIPLIER TUBES^ SHOWING THE SINGLE^

DOUBLE^ AND TRIPLE PHOTOPEAKS. (a) SpECTRUM

TAKEN WITH A SINGLE TUBE. (b) SpECTRA TAKEN WITH

TWO TUBES BROUGHT INTO "REGISTER"^ SO THE PEAKS

LINE UPJ THE DISTRIBUTION FROM ONE OF THE TUBES

IS VISUALLY RAISED FOR CLARIFICATION.
Figure 4. Comparison of the pulse height spectrum of and

OF LUMINOL. In the SCINTILLATOR PPO-TOLUENEy

PRODUCES A BURST OF PHOTONS^ CREATING THE ADDITIONAL PEAKS WITH GREATER PULSE HEIGHTS, WHEREAS

LUMINOL IN REASONABLE CONCENTRATION IS A SINGLEPHOTON EMITTER AND PRODUCES ONLY A SINGLE PEAK.

The spectra are visually offset for clarification.
tVu $

GOVERNMENT

PRINTING

OFFICE

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^U.S

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PRINT'NC

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RESPONSE, ARBITRARY UNITS

ro oi

w M - i 0

a

m

n

1

2

>

r0

>n

0

0

a

0

X

a

<5

i

>

fi

0

1

1

a
(O

^CM O

o

S

UJ

0)O

o

O

CO

lU

(0

UOlOVd 1N3IAI30NVHN3

Figure

11.

Enhancement

factor-vs-sensitizing

dose

(°^Co

gamma

radiation)

for

trehalose,

dissolved

in

luminol

for

LL

READOUT.

Three

levels

of

^^Co

gamma-ray

test

exposures

were

given

to

the

solid

trehalose.

These

ARE

PRELIMINARY

DATA

WITH

A

RELATIVE

STANDARD

DEVIATION

BETWEEN

20

AND

50

PERCENT

BEFORE

NORMALIZATION.
UOiOVd lN3naONVHON3

Figure

12.

Enhancement

factor-vs-dopant

concentration

for

three

dopant

modes

of

trehalose^

dissolved

IN

LUMINOL

FOR

LL

READOUT.

IDENTICAL

TEST

EXPOSURES

(5

RAD

OF

^^Co

GAMMA

RADIATION)

WERE

GIVEN

TO

THE

SOLID

TREHALOSE.
3. (Publication Oat«

August 1983

U.S. OePT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See Instructions}

1. PUBLICATION OR

REPORT NO.

NBSIR 83-2734

2. Parformlnf Orxan. Report No.

4.

TITLE AND SUBTITLE

An Investigation of Lyo luminescence Techniques for Application in Radiation-Protection

Dosimetry

5.

AUTHOR(S)

Dr. Richard Hanig

6.

PERFORMING ORGANIZATION (If joint or other than NBS, see Instructions)

national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, O.C. 20234

7. Contract/Grant No.

S. Typo of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, Stote, ZIP)

NBS

10.

SUPPLEMENTARY NOTES

I I Document describes a computer program; SF-185, FIPS Software Summary, Is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature Survey, mention it here)

A cooled liquid scintillation system with single-photon counting photomultiplier

tubes was employed to increase the sensitivity of luminol- enhanced lyoluminescence

(LL). The problems of reagent purity and mechanical mixing were studied. For the

disaccharide trehalose, the lowest dose significantly different from background was

at the 1.2-rad level for ^®Co gamma rays, with a standard deviation of 33 percent.

The system suffers from poor reproducibility in the mixing of the disaccharide with

its solvent, and recommendations are made for improvements. Detector compounds of

different hydrogen content were studied for possible application in neutron dosimetry

and for their ability to retard free-radical recombination. Tlie results were not con- clusive. Enhancement of the LL effect was accomplished by radiation sensitization of

solutions of trehalose with between 30 and 300 krad to water. The disaccharide was

then recrystallized from solution, along with associated radiolysis products and, in some instances, with separately added chemical dopants. Preliminary intercomparison

of these doped sugars with untreated materials at doses of 1, 5, and 10 rads indicates that they give a better signal -to-background ratio than the untreated disaccharide. A promising reaction model was tried which assumed a two-component exponential decay of light, multiplied by a first-order buildup term for the dissolving

factor. The model seems to fit both the ordinary and luminol -enhanced LL glow-curves.

12. KEY WORDS (S/x to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

chemiluminescence; liquid scintillation counter; luminol; lyoliominescence

;

lyoluminescence enhancement by radiation sensitization; lyoluminescence glow curve

fitting; saccharides

13. AVAILABILITY

1^ I Unlimited

I I For Official Distribution. Do Not Release to NTIS

r I Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

^31 Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

58

15. Price

$ 10.00

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