Jones, S

We present evidence for energetic charged particles emanating from partially-deuterided titanium foils (TiDx) subjected to non-equilibrium conditions. To scrutinize emerging evidence for low-temperature nuclear reactions, we investigated particle yields employing three independent types of highly-sensitive, segmented particle detectors over a six-year period. One experiment measuring neutron emission from TiDx foils showed a background-subtracted yield of 57 ± 13 counts per hour. (The neutron experiments will be discussed in a separate paper.) A second experiment, using a photo-multiplier tube with plastic and glass scintillators and TiDx registered charged particle emissions at 2,171 ± 93 counts/hour, over 400 times the background rate. Moreover, these particles were identified as protons having 2.6 MeV after exiting the TiDx foil array. In a third experiment, coincident charged particles consistent with protons and tritons were observed with high reproducibility in two energy-dispersive ion-implanted detectors located on either side of 25-micron thick Ti foils loaded with deuterium. Our overall data therefore strongly suggest low-level nuclear fusion in deuterided metals under these conditions according to the fusion reactions d + d → n(2.45 MeV) + He(0.82 MeV) and d + d → p(3.02 MeV) + t(1.01 MeV), with other nuclear reactions being possible also. Important advances were particle identifications, and repeatability exceeding 70% for coincident charged particle emissions. Metal processing and establishing non-equilibrium conditions appear to be important keys to achieving significant nuclear-particle yields and repeatability. Introduction For the most part, neutron observations reported as early as 1989 have not been widely accepted. Screening at close range between deuterons in TiDx is expected to be similar to that found in the D2 molecule and insufficient to produce measurable d-d fusion as concluded by Koonin and Nauenberg. Most early attempts at prominent laboratories to replicate such experiments were generally not successful and the situation has also been clouded by the controversy surrounding widely-publicized claims of aneutronic excess heat as reported by Huizenga. Since 1989, however, there have been a number of serious attempts to observe nuclear effects in metal deuterides. Particularly relevant to the present work are experiments of Cecil, Hubler, Menlove, Jones and Wolf. In all these cases, low-level neutron or charged-particle emissions from metal deuterides were seen by experienced individuals working with excellent detectors. The results were not widely published, particle identification was problematic and irreproducibility remained a significant issue. Now, about a decade later, we wish to revisit this problem with fresh ideas and considerable new experimental evidence. Encouraged by our neutron results (separate paper), and wishing to also measure charged-particle emissions, we designed two additional detection systems. The first system incorporated a plastic scintillator mounted on a glass scintillator, mounted in turn on a photo-multiplier tube (PMT). The second system incorporated the use of independent ion-implanted silicon detectors (I-IDs). To reduce background effects, both sets of experiments were conducted in an underground laboratory beneath the Provo campus. We were further motivated in this study by earlier experiments at BYU along these lines as well as experiments of E. Cecil, G. Chambers and G. Hubler and others. Many of the innovations presented here were developed by Particle Physics Research Co. Los Angeles, [10] in consultation with Brigham Young University. We observed charged-particle emissions in excess of 2000 counts per hour. Moreover, using an aluminum energy-degrader in the middle of a high-yield sequence of runs, we were able to identify the charged particles being emitted as protons carrying 2.6 MeV after exiting a TiDx foil, as we shall demonstrate. Detection of Charged Particles Using a PMT/Dual-scintillator System Our first charged-particle spectrometer (Fig. 1) incorporated a 0.0078 gm/cm (76-:m) thick plastic scintillator adhered onto a thicker glass scintillator (0.375 gm/cm) which was glued onto the face of a 12.7-cm diameter photo-multiplier tube (PMT). The detector was housed in a light-tight box equipped with electrical feed-throughs. PMT pulses were digitized at 100 MHz over a 160 :s window. Pulse-shape analysis allowed us to distinguish narrow plastic pulses from glass pulses which are broader in time. When a particle passed through the plastic into the glass, the resulting combined pulse was broad and therefore interpreted as a glass pulse. The integrated area under the pulse reflects the light output of the scintillator(s) which corresponds to the energy of the incident charged particle. As shown in Fig. 2, the plastic scintillator has a non-linear response in that the light output depends on particle energy and identity. The composite spectrometer is also an effective cosmic-ray veto counter since nearly all cosmic rays entering the thin plastic scintillator must also pass through the glass scintillator, producing a characteristic broad (glass-like) pulse seen by the PMT. Cosmic ray pulses were therefore identified and efficiently eliminated. This dual-scintillator counter is a novel detector having the advantage of achieving large-area charged-particle detection conveniently. [8] Fig. 1. Foil array and charged-particle spectrometer system. Fig. 2. Light output for particles stopping in plastic scintillator. Titanium foils for these experiments were 20 x 90 mm and 0.25 or 0.025 mm thick (both thicknesses were tried). The foils were placed inside a stainless-steel cylinder 35 cm in length by 2.5 cm outside diameter. The cylinder was evacuated to about 2 x 10 Torr while being heated with Ti foils inside to approximately 400 C. At this temperature, the cylinder was pressurized with deuterium gas at 15 psi. After a 30-second soak, the cylinder was re-evacuated, thus flushing out unwanted gasses from the cylinder. At approximately 500 C, the cylinder was pressurized with deuterium gas at approximately 40 psi and the inlet valve was closed. A drop in pressure (to about 10 psi for the 0.25 mm-thick foils) clearly demonstrated that the foils within the cylinder became deuterided. By measuring the mass of the foils before and after deuteriding, we found typical d-loadings of 0.5 to 1.4 deuterons per titanium atom. Typically five TiDx foils were assembled in a picket-fence-style array as shown in Fig. 1, then placed on the surface of the detector. The associated electronics were activated and non-equilibrium conditions in the foils were produced by Joule heating. We searched particularly for protons from the fusion of two deuterons according to the reaction d + d → p(3.02 MeV) + t(1.01 MeV). (1) The 3-MeV proton is sufficiently penetrating to escape from about 50 :m (or less) of titanium foil and produce a signal in the energy dispersive detector. On the other hand, exiting tritons have energies below the threshold for this detector. The PMT-detector has the virtue of a large surface area relative to ionimplanted silicon detectors (experiments described below), so that a relatively large sample can be studied in each experimental run. Fig. 3 displays the response of the charged-particle spectrometer to 5.45-MeV alphas particles from an americium-241 source. The pulse-area histogram reflects the 5.45-MeV energy of the alphas and shows the resolution of 760 keV. These data along with Fig. 2 permit energy calibration of the spectrometer for plastic-scintillator pulses, depending on incident particle type. Alphas of this energy all stop in the plastic scintillator and so produce characteristic narrow pulses. Fig. 3. Light output from dual plastic/glass Fig. 4. Spectrum obtained from a 52-minute Scintillator system for americium-241 source. Background run, dual-scintillator detector. Fig. 4 displays the spectrum obtained from a 52-minute background run. In an earlier study, we demonstrated that the majority of the background comes from minimum-ionizing cosmic rays and these produce predominately glass scintillations. The distribution of plastic-pulses is featureless over the background run as shown in Fig. 4. The glass-like pulses are seen to be more frequent but still at a very low rate. Radon was also of concern in these studies since it produces alpha energies up to ~10 MeV and is present in laboratory air. A prominent decay product, Bi-212, beta-decays to Po-212 which then decays via alpha emission with a half-life of 0.3 :s. Fast digitization of pulses enabled us to clearly identify this decay sequence and eliminate such events, which proved to be few. Fig. 5 shows results from a 21-minute run for a set of 3A-Joule heated, deuterium-loaded, titanium foils. We observed two clear groupings, corresponding to signals in the plastic scintillator and in the glass scintillator. Clearly, many particles registered only in the plastic scintillator while others penetrated through the plastic and produced dominating signals in the glass scintillator. Thus we observed two clear peaks completely different from anything ever observed during background runs. The charged particles penetrated through the plastic about one-third of the time to produce glass-dominated pulses, presumably at near-normal angles, while the remainder stopped in the plastic (see Fig. 6). Fig. 5. Spectrum from TiDx array, 21 minutes with dualFig. 6. Schematic of plausible origin of scintillator detector. 3MeV protons degrading through differing thicknesses of titanium at different angles in order to produce glass+plastic pulses of observed energies. For the particles producing plastic-scintillator pulses, the peak in Fig 5 is approximately 1.4 times the light output of the americium alpha peak (Fig. 3). The light-output/energy calibration plot (Fig. 2) shows that these could be (a) alphas having 7.2 MeV, (b) tritons having 3.7 MeV, (c) deuterons having 3.1 MeV, (d) protons having 2.4 MeV, or (e) electrons with 0.7 MeV (approximately; see Table 2). Protons with 2.4 MeV, with sufficiently off-normal angles to stop in the plastic scintillator, could arise from d-d fusion events originating about 12 :m deep in the TiDx foil, as diagramed in Fig. 6; see also Table 1. TABLE 1. Charged-particle identification matrix (Energies in MeV)