Search for long-lived doubly charged Higgs bosons in p(p)over-bar collisions at root s=1.96 TeV

We present a search for long-lived doubly charged Higgs bosons (H+/-+/-), with signatures of high ionization energy loss and muonlike penetration. We use 292 pb(-1) of data collected in p (p) over bar collisions at root s=1.96 TeV by the CDF II detector at the Fermilab Tevatron. Observing no evidence of long-lived doubly charged particle production, we exclude H-L(+/-+/-) and H-R(+/-+/-) bosons with masses below 133 GeV/c(2) and 109 GeV/c(2), respectively. In the degenerate case we exclude H+/-+/- mass below 146 GeV/c(2). All limits are quoted at the 95% confidence level

Uncooled thin film pyroelectric IR detector with aerogel thermal isolation

Uncooled pyroelectric IR imaging systems, such as night vision goggles, offer important strategic advantages in battlefield scenarios and reconnaissance surveys. Until now, the current technology for fabricating these devices has been limited by low throughput and high cost which ultimately limit the availability of these sensor devices. We have developed and fabricated an alternative design for pyroelectric IR imaging sensors that utilizes a multilayered thin film deposition scheme to create a monolithic thin film imaging element on an active silicon substrate for the first time. This approach combines a thin film pyroelectric imaging element with a thermally insulating SiO{sub 2} aerogel thin film to produce a new type of uncooled IR sensor that offers significantly higher thermal, spatial, and temporal resolutions at a substantially lower cost per unit. This report describes the deposition, characterization and optimization of the aerogel thermal isolation layer and an appropriate pyroelectric imaging element. It also describes the overall integration of these components along with the appropriate planarization, etch stop, adhesion, electrode, and blacking agent thin film layers into a monolithic structure. 19 refs., 8 figs., 6 tabs

Effect of Substrate Composition on the Piezoelectric Response of Reactively Sputtered AlN Thin Films

Deposition parameters were found to have a marked effect on piezoelectric response of reactive radio frequency (RF) sputtered AlN thin films. The authors observed peizoelectric response values ranging from {minus}3.5 to +4.2 pm/V for 1 {micro}m thick AlN films deposited onto Ti/Ru electrode stacks. An investigation of the effects of deposition parameters, in particular the nature of the Ru/AlN interface, was conducted. The lag time between deposition of adjacent thin film layers appeared to have the greatest affect on the value of the piezoelectric response. This suggests that chemical reaction occurring on the Ru thin film surface is responsible for changing an important thin film property such as dipole orientation within the overlying AlN thin film

RF magnetron sputter-deposition of La{sub 0.5}CoO{sub 3}//Pt composite electrodes for Pb(Zr,Ti)O{sub 3} thin film capacitors

La{sub 0.5}Sr{sub 0.5}CoO{sub 3} (LSCO) thin films have been deposited using RF magnetron sputter-deposition for use as an electrode material for PZT (PbZrTiO{sub 3}) thin film capacitors. Effect of O{sub 2}:Ar sputter gas ratio during deposition, on LSCO film properties was studied. It was found that the resistivity of the LSCO films deposited at ambient temperature decreases as the O{sub 2}: Ar ratio was increased for both as-deposited and annealed films. It was also found that thin overlayers of LSCO tend to stabilize the underlying Pt//Ti electrode structure during subsequent thermal processing. The LSCO//Pt//Ti composite electrode stack has a low resistivity and provides excellent fatigue performance for PZT capacitors. Furthermore, the LSCO//Pt//Ti electrode sheet resistance does not degrade with annealing temperature and the electrode does not display hillock formation. Possible mechanisms for the stabilization of the Pt//Ti electrode with LSCO overlayers are discussed

La{sub 0.5}Sr{sub 0.5}CoO{sub 3} electrode technology for Pb(Zr, Ti)O{sub 3} thin film nonvolatile memories

Oxide electrode technology is investigated for optimization of Pb(Zr,Ti)O{sub 3} (PZT) thin film capacitor properties for high density nonvolatile memory applications. PZT thin film capacitors with RF sputter deposited La{sub 0.5}Sr{sub 0.5}CoO{sub 3} (LSCO) electrodes have been characterized with respect to the following parameters: initial dielectric hysteresis loop characteristics, fatigue performance, microstructure and imprint behavior. Our studies have determined that the fatigue of PZT capacitors with LSCO electrodes is less sensitive to B site cation ratio and underlying electrode stack technology than with RuO{sub 2} electrodes. Doping PZT thin films with Nb (PNZT) improves imprint behavior of LSCO//PZT//LSCO capacitors considerably. We have demonstrated that PNZT 4/30/70 // LSCO capacitors thermally processed at either 550{degrees}C or 675{degrees}C have almost identical initial hysteresis properties and exhibit essentially no fatigue out to approximately 10{sup 10} cycles

Surface Micromachined Flexural Plate Wave Device Integrable on Silicon

Small, reliable chemical sensors are needed for a wide range of applications, such as weapon state-of-health monitoring, nonproliferation activities, and manufacturing emission monitoring. Significant improvements in present surface acoustic wave sensors could be achieved by developing a flexural plate-wave (FPW) architecture, in which acoustic waves are excited in a thin sensor membrane. Further enhancement of device performance could be realized by integrating a piezoelectric thin film on top of the membrane. These new FPW-piezoelectric thin film devices would improve sensitivity, reduce size, enhance ruggedness and reduce the operating frequency so that the FPW devices would be compatible with standard digital microelectronics. Development of these piezoelectric thin film // FPW devices requires integration of (1) acoustic sensor technology, (2) silicon rnicromachining techniques to fabricate thin membranes, and (3) piezoelectric thin films. Two piezoelectric thin film technologies were emphasized in this study: Pb(Zr,Ti)O{sub 3} (PZT) and AlN. PZT thin films were of sufficient quality such that the first high frequency SAW measurements on PZT thin films were measured during the course of this study. Further, reasonable ferroelectric properties were obtained from PZT films deposited on Si surface micromachined FPW device membranes. Fundamental understanding of the effect of nanodimension interfacial layers on AlN thin film domain configurations and piezoelectric response was developed. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the US Department of Energy under contract DE-AC04-94AL85000

Observation of Three-Neutron Sequential Emission from ²⁵O

Background: Measurements of neutron-unbound states can test nuclear models in very neutron-rich nuclei that in some cases cannot be probed with other methods. Purpose: Search for highly excited neutron-unbound states of 25O above the three neutron separation energy. Method: The decay energy of 25O was reconstructed using the invariant mass spectroscopy method. A 101.3 MeV/u 27Ne beam collided with a liquid deuterium target. Two-proton removal reactions populated excited 25O that decayed into three neutrons and an 22O fragment. The neutrons were detected by arrays of plastic scintillator bars, while a 4 Tm dipole magnet placed directly after the target redirected charged fragments to a series of charged-particle detectors. The data were compared with detailed Monte Carlo simulations of the reaction process and subsequent decay. Results: The data show evidence of neutron-unbound level(s) in 25O at an excitation energy of about 9 MeV which decay sequentially by the emission of three neutrons to 22O. Conclusion: The observation of resonance strength in 25O at about 9 MeV is consistent with shell-model/eikonal calculations for the two-proton removal reaction from 27Ne.</p