This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Fisher, J.H.

Foster, C.C.

Holland, L.R.

Hollerman, W.A.

Jenkins, G.M.

Nisen, D.B.

Shelby, G.A.

Williams, E.K.

English

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APPLICATIONS 
MEASUREMENT OF FLUORESCENCE PHENOMENA FROM YTTRIUM AND 
GADOLINIUM OXYSULFIDE PHOSPHORS USING A 45-MeV PROTON BEAM 
W.A. Hollerman, J.H. Fisher, and G.A. Shelby 
Nichols Research Corporation, Huntsville, Alabama 35802 
L.R. Holland, G.M. Jenkins, D.B. Nisen, and E.K. Williams 
Alabama A & M  University, Normal,  Alabama 35762 
C.C. Foster 
Indiana University Cyclotron Facility, Bloomington, Indiana 47408 
Since 1989, Alabama A&M University and Nichols Research Corporation have been 
actively involved in research to determine proton-induced damage and its effect on rela- 
tive scintillation efficiency for various yttrium and gadolinium oxysulfide phosphors. The 
phosphor materials were selected for high efficiency, fast prompt fluorescence reponse, and 
minimal delayed fluorescence. Real time, in-situ measurements of the fluorescence spectra 
permitted observation of the spectral characteristics for the deterioration of scintillation 
yield due to particle induced damage. 
In December 1992, six different phosphors compounds (Gd2 O2 S:Pr, Gd2 O2 S:Tb, 
Gd202S:Eu, Y202S:Eu, YAG:Ce and ZnS:Ag) were exposed to a 45-MeV proton beam 
at the Indiana University Cyclotron Facility (IUCF) using the High Energy Materials Ir- 
radiation Chamber (HEMIC) located in the K600 spectrometer cave. The HEMIC will 
provide physicists and material scientists the capability of exposing a variety of phosphor 
samples in a controlled temperature environment to ion bombardment with energies from 
45 to 200 MeV. 
The HEMIC consists of a specially constructed 6-way stainless-steel cross 504-mm long 
and 101.6-mm in diameter. The incident beam impinges on a phosphor sample painted 
on a 51-pm thick and 25-mm wide copper ribbon. The phosphor ribbon can be translated 
to any one of 16 different irradiation positions that are each 13 mm apart. The ribbon 
is maintained in a slightly stretched condition to avoid gravity sag and provide a smooth 
sample surface. Samples are applied to the copper ribbon using spray technology with a 
polysiloxane paint binder. 
A crossed Czerny-Turner design Jerrell Ash Monospec 18 grating spectrometer with 
an EG&G type 1453A 1024-element linear silicon photodiode array is used to detect the 
spectral output from the phosphor being irradiated. A 300 groove/rnm diffraction grating 
was used to center the resulting fluorescence spectra at a wavelength of 500 nm. The spec- 
trometer was mounted on an x-y translation stage to provide accurate sample alignment 
at IUCF. 
An Omega Engineering OS42 temperature transducer with a close focus head was used 
to detect the temperature from the back of the phosphor coated ribbon. The back of the 
ribbon was painted with a lampblack-based polysiloxane paint to increase the emissivity 
of the sample to allow for simple measurement of the sample temperature. The use of the 
OS42 provided a non-contact method to measure the ribbon temperature at the irradiation 
position. A zinc selinide infrared window with a hard optical coating was used as a vacuum 
seal for the HEMIC chamber. The vacuum integrity of HEMIC was tested to pressures of 
less then Torr which is sufficient for use at IUCF. 
Beam current and the subsequent total proton dose hitting the copper ribbon is mea- 
sured at a facility-supplied Faraday cup and current integrator. All resulting spectroscopic, 
temperature, and beam data were collected, stored, and analyzed using a Macintosh IIfx 
computer system running the LabView 2 Software program from National Instruments 
Corporation. 
The development of HEMIC is a natural outgrowth of previous efforts completed by 
the authors in 1989 to 1991 with the development of the Fluorescent Materials Test Cham- 
ber (FMTC) for low-energy (around 3 MeV) protons at the Alabama A&M University 
Pelletron accelerator laboratory. 
Data obtained at IUCF indicated that the measured proton dose required to reduce 
the fluorescence brightness to half its original value (half-brightness dose) at 45 MeV is 
between 2 and 22 times larger when compared to corresponding values measured previously 
by the authors at 3 MeV. Although fewer protons interact with the phosphor at 45 MeV, 
each of the individual particles that do interact causes more damage to the material than 
equivalent protons at 3 MeV. The average incident beam current at IUCF was about 
170 nA over an area of 7 mm2. 
The measured 45 MeV half-brightness proton dose at 150 "C is between 0.1 and 1.5 
times larger than equivalent data observed at ambient temperature. The difference in 
proton half-brightness dose due to elevated sample temperature at 3 MeV is similar to 
the data taken at IUCF. The wavelength, net shape and amplitude of individual phosphor 
peaks is similar at 45 MeV when compared to equivalent data taken previously by the 
authors at 3 MeV. Experimental data also suggest that the magnitude of fluorescence light 
emitted at 150 "C is smaller than was observed at ambient temperature at both 3 and 
45 MeV. One particular Gd2 O2 S:Tb irradiation measurement indicates that the magnitude 
for the resulting fluorescence was increased about 63 times when the temperature was 
reduced from 150 "C to 113 "C. 
This research was completed as part of the Fluorescent Materials and Bonding: Ex- 
tended Energy (FMAB:EE) program under contract DASG60-90-C-0144 for the U.S. Army 
Space and Strategic Defense Command (USASSDC). The authors would like to thank the 
management and technical staff of IUCF for allowing the FMAB:EE team to have access 
to 36 hours of beam over the 1992 Thanksgiving weekend. The FMAB:EE team would 
especially like to thank Dr. C. C. Foster of the IUCF staff for his tireless effort in the 
successful competion of this test event. 
1. J.B. Birks, Proc. Phys. Soc. (London) A63, 1294 (1950). 
2. J.B. Birks, Proc. Phys. Soc. (London) A64, 874 (1951). 
3. J.B. Birks and F.A. Black, Proc. Phys. Soc. (London) A64, 511 (1951). 
4. F.A. Black, Phil. Mag., 44, 263 (1953). 
5. I. Broser and H. Kallmann, Z. Naturforsch, A, 2, 439 (1947); ibid. 2, 642 (1947). 
6. W.A. Hollerman, J.H. Fisher, G.A. Shelby, L.R. Holland, and G.M. Jenkins, IEEE 
Trans. Nucl. Sci., NS38, 184 (1991). 
7. L.R. Holland, G.M. Jenkins, J.H. Fisher, W.A. Hollerman, and H.A. Shelby, Nucl. 
Instrum. Methods B 56, 1239 (1991). 
8. W.A. Hollerman, J.H. Fisher, G.A. Shelby, L.R. Holland, and D.B. Nisen, Nucl. In- 
strum. Methods B 68, 29 (1992). 
9. W.A. Hollerman, J.H. Fisher, G.A. Shelby, L.R. Holland, and G.M. Jenkins, IEEE 
Trans. Nucl. Sci., NS39, 2295 (1992). 


Measurement of Fluorescence Phenomena from Yttrium and Gadolinium Oxysulfide Phosphors using a 45-MeV Proton Beam

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Measurement of Fluorescence Phenomena from Yttrium and Gadolinium Oxysulfide Phosphors using a 45-MeV Proton Beam

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