PFC/JA-89-24 Rev.
t-Rav Spetra in the Fleischmann.
Pons. Hawkins Eapment
R. D. Petrasso, X. Chen, K. W. Wenzel,
R. R. Parker, C. K. Li, and C. Fiore
Plasma Fusion Center
Massachusetts Institute of Technology
Cambridge, MA 02139
April1989
This work was supported in part by the U. S. Department of Energy Contract No.
DE-AC02-78ET51013.
Presented at the American Physical Society Meeting, May 2, 1989, Baltimore,
Maryland. Accepted by Nature.

-2y-Ray Spectra in the Fleischmann.
Pons. Hawkins Experiment
R. D. Petrasso, X. Chen, K. W. Wenzel,
R. R. Parker, C. K. Li, and C. Fiore
Plasma Fusion Center
Massachusetts Institute of Technology
Cambridge, MA 02139
Abstract
Fleischmann, Pons, and Hawkins (FPH)1, 2 recently announced that significant fusion heating was occurring in their cold fusion experiments. As compelling evidence of fusion processes, they reported the detection of 2.2 MeV
y rays that result from neutron-capture-on-hydrogen.
We have carefully analyzed the published y-ray spectra of FPH. We have also performed detailed terrestrial y background measurements and neutroncapture-on-hydrogen experiments. From our analyses we conclude that the
FPH y line is specious on the basis of three quantitative considerations: (1) it has a line width a factor of 2 smaller than the detector instrumental resolution would allow at 2.2 MeV; (2) there is no evidence of a Compton edge at 1.99 MeV
(i.e., 2.22 MeV 0.23 MeV), and this edge should be distinctly prominent; and (3)
FPH's estimate of the neutron source rate, based on their purported y signal, is a factor of 50 too large. Additionally, from terrestrial y background considerations, we argue that FPH's y "line" actually resides at 2.5 MeV rather than 2.2 MeV. Based on these arguments, we conclude that the y signal of FPH cannot be the 2.2 MeV neutron-capture-on-hydrogen y ray. We can offer no plausible explanation for the feature, other than it is possibly an instrumental artifact unrelated to a y-ray interaction.

-3-
I. Introduction
Fleischmann, Pons, and Hawkins 1 (henceforth FPH) recently announced
2 the observation of significant heating in their cold fusion experiments, a result which they attribute to copious fusion production. As compelling evidence of the occurrence of fusion processes, FPH reported to observe the 2.22 MeV y-ray line that originates from neutron-capture-on-hydrogen
3 ,4 n + p -+ D + y (2.22 MeV). (1)
They contend that the neutron in (1) is generated via the reaction
D + D -+ n + He 3 (2) and, therefore, conclude that (a) the 2.22 MeV y ray identifies that process (2) is occurring; and (b) that a neutron source rate of the order of 4 x 104/s is derivable from their y signal rate. They further state that most of the heat generation occurs not through process (2), but through a hitherto unknown nuclear fusion process.
This paper focuses solely on the identity of their reported y-ray line, which we henceforth call the Signal Line. We will argue herein that FPH's conclusion of having observed the 2.22 MeV line of Equation 1 is unfounded. We will do this on the basis of three quantitative considerations: (1) the line width is a factor of
2 smaller than their instrumental resolution would allow; (2) a clearly defined
Compton edge, which should be evident in their published data at 1.99 MeV, does not exist; and (3) their estimated neutron rate is in error by a factor of 50, i.e., it is 50 times too large. These conclusions are, in part, based on neutron-captureon-hydrogen experiments using a well-calibrated neutron source (1.5 x 106 n/s
Pu/Be source) that was submerged in water. The results show a line at 2.2 MeV of the proper line width for our spectrometer and theirs. Also evident in our spectra are other critical identifying features of the 2.2 MeV y ray, i.e., the
Compton edge (at 1.99 MeV), and the first (1.7 MeV) and second (1.2MeV) pair escape peaks.

-4-
II. Inconsistencies in the y Line of Reference 1
In this section we raise three quantitative objections regarding the nature and consequences of the reported 2.2 MeV y line of FPH 1 (Figure 2 herein). The first concerns its line width; the second, the absence of the Compton edge 5 that should have been clearly present in their published data (Figure 2); and the third, their overestimate of the neutron source rate by a factor of 50. In Section
IId we argue that FPH's Signal Line occurs at 2.5 MeV, not 2.2 MeV.
A. Energv Resolution
We have measured terrestrial y-ray background at MIT in order to verify the FPH results. Figure la shows a typical y-ray terrestrial background spectrum obtained with a 3" x 3" NaI(Tt) crystal spectrometer system. Citation
12 discusses many details of our measurements for various sites, shielding conditions, crystals, and it also specifies germane spectrometer parameters.
Throughout the terrestrial environment, the main features of this spectrum are quite similar.
7 , 8 Of particular importance to this work, Fleischmann, Pons, and
Hawkins showed a similar y-ray spectrum on local (KSL-TV/Utah) 2 ,11 and national (CNN) television (Figure 1b). 2 This spectrum was obtained in the course of FPH's experiments, as confirmed by M. Hawkins 6 (of FPH). Their spectrometer system was comprised of a Nuclear Data ND 6 portable analyzer with a 3" x3" NaI (T) crystal 6 ,13,1, 2 . A 3/8"-thick Pb annulus encompassed the scintillator 6 , 13 , 2 . By comparing Figures 1 a and 1b, especially the K 40 (1.46 MeV) and T 2 0 8 (2.61 MeV) lines, one can see that our resolution is comparable to or better than the FPH spectrometer, a point which we will return to shortly.
In the interval from 1.46 MeV to 2.61 MeV, the energy resolution of a
NaI(Tt) spectrometer, which is the property that determines the line width, can

-5be well described by the formula 1 4 , 1 5
(3)
AE is the full-width-at-half maximum of the line, E is the energy of the photon, and R(En) is the measured "reference" resolution at energy En. R(En) can be accurately determined by a C0 60 source (using the line at 1.33 MeV), or it can be fairly well approximated by the K 4 0 -decay line at 1.46 MeV.
1 6 For example, the value of R (En = 1.46 MeV), as determined from Figure 1 a, is about 5.5%. Using this value in Equation 3, the predicted FWHM for the 2.22 MeV line is about
4.5%. (See Table la for a complete listing of our measured and predicted line widths.) If instead the C0 6 0 source is used (1.33 MeV; for which
R (1.33 MeV) = 5.1%) as the reference, the predicted 2.22 MeV line width is about
4.0%. For comparison, we also list in Table lb the resolution data that is based on the FPH televised spectrum 2 and laboratory calibrations.
13
We now report on the measured line width obtained from neutroncapture-on-hydrogen experiments that we recently performed in our laboratory
(Figures 3 and 4). These experiments involved placing a 1.5 x 106 n/s Pu/Be
17 neutron source in a water tank. (
94
Pu 2 3 9 emits energetic a particles which produce neutrons through (a, n) reactions with Be.
5 , 1 5 ) The neutrons are thermalized in water, and we observe the emitted neutron-capture y rays with our spectrometers. The measured line width at 2.2 MeV is about 5% (Table 1a).
Note that the expected line width of the 2.2 MeV y ray is reasonably well predicted by Equation 3. As a consequence, this calls into serious question the identity of the Signal Line as a y line. Specifically, Figure 2 shows the Signal

-6-
Line to have a resolution of 2.5%. This is about a factor of 2 smaller than predicted via Equation 3 on the basis of the known resolution (Table 1b) from either the K 4 0 decay line (1.46 MeV)
13 , 16 , 2 or from the C060 (1.33 MeV) source.
1 3
Since we know from Table 1 that the FPH spectrometer has a resolution at best comparable to our own for the entire region from 1.46 to 2.61 MeV (see also
Figures la and 1b), it is inconsistent that their line width at 2.22 MeV is a factor of two below the predicted value.
B. Spectral Shape
There is another inconsistency with the published Signal Line (Figure 2).
If we assume a resolution of 2.5% at 2.22 MeV, then there should be a clearly defined Compton edge 5 at 1.99 MeV. For example, in Figures 3 and 4 the
Compton edge is evident even for our measured resolution of only 5%. For a resolution of 2.5%, the definition of the Compton edge would be distinctly sharper. Therefore, the lack of a Compton edge at 1.99 MeV for the Signal Line
(Figure 2) negates the conclusion of FPH that they have observed the 2.22 MeV neutron-capture-on-hydrogen gamma.
It is also worthwhile pointing out that in our (Pu/Be) neutron-capture experiments, a conspicuous e+ e- annihilation single escape peak exists at 1.7
MeV (Figures 3 and 4a) as well as a double escape peak at 1.2 MeV (Figure 4a).
Such features unambiguously identify the primary y rays to have an energy of
2.2 MeV (see References 3 and 4) and are a necessary consequence of the physical process of detection of gamma rays in a finite size NaI scintillator.
C. Neutron Rate According to the 2.2 MeV y Rate
Based on both their gamma Signal Line and neutron measurements, FPH

-7claim to have observed a neutron rate of the order of 4 x 10 4 /s.
1 This claim cannot be correct for the following quantitative reasons. The Pu/Be neutron source used in our experiment is absolutely calibrated to within 10% of 1.5 x 106 n/s.
1 7 In obtaining the data in Figure 3, we used a setup similar to that of
FPH 1 , 2 , and as described by M. Hawkins
6 and R. Hoffman.
1 3 Our Pu/Be source was submerged 6" into a large water tank. The measured 2.2 MeV y rate was 1.7 x 10 3 /MeV-s (see Figure 3). Scaling this rate to a neutron source of 4 x 104 n/s, i.e., the level given by FPH, gives a total y rate of about 4.5 counts/s in the line.
This value is a factor of 50 higher than the rate calculable from Figure 1 a of FPH
(i.e., 0.081 counts/s ).18 While differences of a factor of 2 in rates might possibly be explained on the basis of geometry, a factor of 50 is inexplicable.
D. Energy Location
A further point concerning the identification of the Signal Line shown in
Figure 2 is the precise value of the energy at which the peak occurred. From
Figure 2, the background in the neighborhood of the peak is seen to be approximately 80 counts per channel, a level which would correspond to about
400 counts per channel for a 48-hour accumulation time. (The data in Figure 2 was accumulated for a period of 10 hours.
1 ) On the other hand, in the Utah terrestrial y-ray background measurements, the level in the vicinity of 2.2 MeV was found to be in the range of -4000 counts per channel.
1 3 The only relevant part of the entire y-ray spectrum (i.e., between 1.46 and 2.61 MeV) where the background was as low as 400 counts was at an energy in the vicinity of
2.5 MeV.
1 3 Thus, we argue that the peak in the spectrum shown in
Figure 2 is at 2.5 MeV, not 2.2 MeV.
The importance of properly identifying the energy of the feature claimed

-8-
by FPH can hardly be overemphasized. Thus, it seems extremely peculiar that they chose to display only the energy range 1.9 2.3 MeV in their published
Figure 1 a, thereby not providing the supporting evidence of the K
40
(1.46 MeV) and T 2 08 (2.61 MeV) features which must be present in their spectra in order for their identification to be correct.
III. Conclusions
We have analyzed published
1
,
2 and unpublished
6
,1
3 information regarding the y-ray spectra relevant to the Fleischmann, Pons, Hawkins experiments. Additionally we have compared this data with results of 7-ray experiments specifically designed to test critical features. One set of experiments involved measuring the natural background y radiations and establishing the accuracy of an absolute energy calibration and detector resolution between 1.46 MeV (K
4 0
) and 2.61 MeV (T
2 08
). Another set of experiments involved detecting the 2.22 MeV y line by submerging a (Pu/Be) neutron source into a water bath. The latter measurements clearly identified the 2.22 MeV capture y ray as well as other critical structures (i.e., the Compton edge, the first and second escape peaks, and the line width). The analysis showed: (1) the FPH line width at the reported 2.2 MeV y ray to be a factor of two smaller than their instrumental resolution would allow at that energy; (2) that there is no indication of the Compton edge which should be distinctly evident at
1.99 MeV; and (3) that the neutron source strength reported by FPH is in error by a factor of 50, i.e., their actual strength should be 50 times smaller.
Furthermore, we argue their purported y line actually resides at 2.5 MeV, not at

-9-
2.2 MeV. Therefore, while it seems clear that FPH have observed a change in their y spectra bearing some correlation with detector location
6 ' 1 3 '1, we conclude that it is unrelated to the 2.22 MeV neutron-capture y rays. We can offer no plausible explanation for the feature other than it is possibly an instrumental artifact with no relation to a y-ray interaction.
Acknowledgements
We gratefully acknowledge the assistance of our colleagues Mr. Christian
Kurz and Mr. Frederick F. McWilliams. For the use of a spectrometer system, we thank Professor George W. Clark. For clarifying discussions, we thank Mr.
Marvin Hawkins and Mr. Robert Hoffman of the University of Utah. For valuable suggestions and criticisms throughout the course of this work, we are especially grateful to Dr. George R. Ricker, Jr. and Professor Dieter J. Sigmar.
We are indebted to Ms. Janet K. Anderson for assembling this document. For locating important references, we thank Ms. Kathleen A. Powers. Supported in part by the U S. Department of Energy Contract No. DE-AC02-78ET51013.

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References
1. M. Fleischmann, S. Pons, and M. Hawkins, J. Electroanal. Chem. 26i
(1989) 301-308; and errata.
2. CNN-TV; KSL-TV (Utah); 3/24/89 and thereafter.
3. B. Hamermesh and R. J. Culp, Phys. Rev. 22 (1953), 211.
4. R. C. Greenwood and W. W. Black, Phys. Letts. fi (1966) 702.
5. Glenn F. Knoll, Radiation Detection and Measurement, John Wiley &
Sons, Inc. (1979).
6. Marvin Hawkins, University of Utah, private communications (1989).
7. M. Eisenbud, Environmental Radioactivity, Academic Press, New York and London (1973).
8. J. A. S. Adams and W. M. Lowder, The Natural Radiation Environment,
The University of Chicago Press, Chicago and London (1964).
9. Michael C. Lederer, Jack M. Hollander, and Isadore Perlman, Table of
Isotopes, 6th Edition, John Wiley & Sons, Inc. (1967).
10. As explained in Reference 9, the immediate parent of the final decay product is identified. For example, K
4 0 0+ decays into an excited nuclear state of Ar 4 0 , which actually then emits the 1.460 MeV photon discussed throughout the text.

-11-
11. We believe we have viewed all the cold fusion y spectra shown on
KSL-TV (Utah) that occurred up until 4/19/89. (This information was assembled by Utah News Clips, Inc., Salt Lake City, Utah.) As best we can tell, all spectra are identical to that of Figure 1b.
12. The terrestrial y-ray background and neutron-capture-on-hydrogen y-ray spectra were measured at MIT in order to check the FPH results. Two 3" x 3" NaI(T) scintillation detectors were principally used in the measurements (one from Canberra and one from Harshaw). These detectors have the same crystal size as the one used by FPH, 6 ,13,2 and are expected to have comparable resolution. The amplifiers used were EG&G
Ortec Model 113 preamplifier and Model 572 amplifier, respectively. The spectra were recorded with both multichannel analyzers (Norland Model
5300) and CAMAC pulse height analysis modules (LeCroy Model 3512,
3587, 3588). The background y-ray spectra were measured at several different locations (in two buildings about 100 m apart) and with different shielding arrangements. For the same shielding conditions at different locations, the measured y-ray spectra are similar and their intensity variation is within 25 percent. The ratio of spectral features from 1.46 to
2.61 MeV varies weakly with diverse shielding conditions, but the absolute level (referenced to K 4 0 (1.46 MeV)) can vary by a factor of 20, i.e., from no shielding to entombment in 4" thickness of Pb. The data shown in Figure la was obtained with the detector surrounded by 4" of lead, except at the front end of the detector which viewed a large water tank.
The data shown in Figures 3 and 4 were obtained with the detector shielded with a 3/8" thick, 15" long lead pipe and that was located over a water tank. FPH also used 3/8" thick Pb for their detector shielding 6 , 1 3 , 2 .

-12-
(From the data we obtained (see Table 1), our spectrometers have somewhat better resolution.)
13. Robert Hoffman, University of Utah, private communications (1989).
14. Harshaw Radiation Detectors, Scintillation Counting Principles, 6801
Cochran Road, Solon, Ohio, 44139 (1984).
15. C. E. Crouthamel, Applied Gamma-Ray Spectrometry, 2nd Edition by F.
Adams and R. Dams, Pergamon Press, Ltd. (1970).
16. From Figure 1b, the K 40 -decay line allows one to estimate the FPH resolution as about 8% (see also Table 1b).
17. W. F. Reilly, M.S. Thesis, MIT (1959); and Frederick F. McWilliams, MIT
Reactor Radiation Protection Officer.
18. FPH state that their neutron count rate is measured over a 0.4 mm x 10 cm Pd cell and that the y measurement is over a 0.8 mm x 10 cm Pd cell.
1
If the total reaction rate is proportional to the volume of Pd rod, as stated
by FPH, the inconsistency in the reported neutron rate is by a factor of 200 rather than 50.

-13-
TABLE 1 a) Resolution of MIT spectrometers
Source
Energy (MeV) 1.17 1.33 1.46 2.22
Identity
Natural Background
Co CP" K
4
.055 n(p,-y)d
2.61
T-12
.043
(.041)
Co6
.056 .051
Pu/Be neutron source .05
(.045)
b) Resolution of the Reference 1 spectrometer
Energy (MeV) 1.33 1.46
Reference Identity
R. Hoffman'
3
C
.056 .065
2.22 2.61
K* n(p,y)d Tl
2
'
TV News
2
~ .08 ~.05
(.049)
Reference 1 .025
(.053)
Table 1 Comparison between the energy resolution of the 7-ray spectrometers used in MIT measurements (Table 1a) and the one used in the FPH experiments (Table 1b).
The resolution is defined as the full-width-half-maximum (FWHM) divided by the peak energy. The numbers in the parenthesis are predicted values based on the detector resolution at 1.46 MeV (see text). In Table lb the prediction is based on the resolution value (0.065 at 1.46 MeV) provided by R. Hoffman".

-14-
C c- o
0a) -
6--
3 agAc
2 2 8
S(.912) asBi 2 1 4
(1.12)
40
(1.460)
Dominantely
83Bi
2 14
(1.764) s3B 214
42.117 1
2
2.
2 0 4
1
(2.615)
0
.4 .9 1.4 1.9 2.4 2.9
Energy (MeV) b)
Fig. 1 Comparison of the y-ray background spectrum measured at MIT
(top) and the y-ray spectrum shown on television by FPH
2 ,6
(bottom). a) The background spectrum measured with a 3" x 3"
NaI(Tt) detector at MIT. Some important terrestrial y-ray lines have been identified in this figure.
7 -' 0 The spectrum is averaged over an 84-hour run. b) The y-ray spectrum of FPH.
2 , 6 The main characteristics of the two spectra are similar; one can also tell that the two detectors have comparable spectral resolution. In Figure
1b, note the curious structure at about 2.5 MeV as well as that beyond the T 2 08 peak (2.61 MeV), which appear to be artifacts. (The
Figure lb spectrum can be obtained from KSL-TV in Utah.
6 , 1 1 )

-15--
800
100
400
200 00
00
2000 2200
/ K*V
2400
Fig. 2 A reproduction of the purported 2.2 MeV y-ray Signal Line of FPH
(Figure la of Reference 1, errata.). The resolution, based on the
Signal Line width, is about 2.5%. With such resolution, one would expect to see a clearly defined Compton edge at 1.99 MeV. No edge is evident. Also, a resolution of 2.5% is inconsistent with their spectral resolution, as clearly evident from Table 1b. Furthermore, we argue the Signal Line resides at 2.5 MeV, not 2.2 MeV as is depicted by FPH.

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2000 .
,
1500single escape peak
1000-
Compton edge
0
C
0
500
(n,7) peak
(2.22)
0
1.5
I
1.8 2.1
I
I I
2.4 2.7 3.0
Energy (MeV)
Fig. 3 y-ray spectrum measured by a 3" x 3" NaI(T) spectrometer during a neutron-capture-on-hydrogen experiment, which utilized a
(Pu/Be) neutron source submerged in water. Because of the finite size of the crystal (which is identical to that of FPH (Reference 1)), we also see an escape peak and, of particular importance to this paper, the Compton edge (identified in the figure). The single escape peak is caused by the loss of the 0.511 MeV photons which are generated during e+-e- annihilation. The Compton edge is determined by the maximum energy an electron can obtain in a single Compton interaction. The energy gap between the Compton edge and the incident photon energy is 0.23 MeV for 2.22 MeV
y rays. (In Figures 3 and 4, the digitization energy width is 0.024
MeV/channel.)

-17-
4000 n
3000 double escape peak single escape peak (n,y) peak
(2.22)
Compton edge
4_j
0
1000-
0+
150a)
100-
D
0
K4
(1.460)
50-
~
'T12z b) (2.615)
0 -F I I I I I I I I
.5 1.0 1.5 2.0 2.5 3.0
Energy (MeV)
Fig. 4 The full y-ray spectrum measured at MIT in a neutron-capture-onhydrogen experiment, which utilized a (Pu/Be) neutron source submerged in water. a) The y-ray spectrum due to (n, y) reaction.
One can see the single and double pair escape peak, and of particular importance to this paper, the Compton edge. b) The y-ray background measured with the same experimental setup and at the same location during a 24-hour period prior to the neutron experiment. See Citation 12 for the experimental arrangement.