Design and fabrication of Cherenkov flux-flow oscillator

The Josephson Flux-Flow Oscillator (FFO) has been used as an on chip local oscillator at frequencies up to 650 GHz. The FFO linewidth of about 1 MHz was measured in the resonant regime at V <915 mu V for niobium - aluminum oxide - niobium tunnel junctions, while considerably larger values were reported at higher voltages. To overcome this fundamental linewidth broadening we propose a novel on chip Cherenkov radiation flux-flow oscillator (CRFFO). It consists of a long Josephson junction and a superconducting slow wave transmission line that modifies essentially the junction dispersion relation. Two SIS detectors are connected both to the long Josephson junction and the transmission line to evaluate available microwave power. The output power coming both from the long junction and the transmission line is estimated at different bias conditions

First implementation of the fully superconducting 500 GHz receiver with integrated flux-flow oscillator

An integrated quasioptical receiver consisting of a planar double dipole antenna, SIS mixer and a superconducting local oscillator with matching circuits has been designed, fabricated and tested. A Flux-Flow Oscillator (FFO) based on unidirectional viscous flow of magnetic vortices in a long Josephson tunnel junction is employed as a local oscillator. All components of the receiver are integrated on a 4 mm x 4 mm x 0.2 mm crystalline quartz substrate on a base of the same Nb-AlOx-Nb trilayer in one technological run. The receiver has been studied in the frequency range 360 - 490 GHz. A lowest DSB noise temperature of 470 - 560 K has been achieved within the frequency range 425 - 455 GHz. Test circuits each comprising a FFO and a SIS detector have been experimentally investigated at frequencies up to 850 GHz. A new reliable technique for measuring the spectral linewidth of the integrated oscillators has been developed; the possibility of frequency locking of a FFO to an external microwave source has been demonstrated. The spectral linewidth of a FFO has been measured in the frequency range 250 - 580 GHz; a linewidth as low as 200 kHz is obtained at 450 GHz

Commissioning of a high pressure time projection chamber with optical readout

The measurements of proton–nucleus scattering and high resolution neutrino–nucleus interaction imaging are key in reducing neutrino oscillation systematic uncertainties in future experiments. A High Pressure Time Projection Chamber (HPTPC) prototype has been constructed and operated at the Royal Holloway University of London and CERN as a first step in the development of a HPTPC that is capable of performing these measurements as part of a future long-baseline neutrino oscillation experiment, such as the Deep Underground Neutrino Experiment. In this paper, we describe the design and operation of the prototype HPTPC with an argon based gas mixture. We report on the successful hybrid charge and optical readout using four CCD cameras of signals from241 Am sources

Off-axis characterisation of the CERN T10 beam for low momentum proton measurements with a high pressure gas time projection chamber

We present studies of proton fluxes in the T10 beamline at CERN. A prototype high pressure gas time projection chamber (TPC) was exposed to the beam of protons and other particles, using the 0.8 GeV/c momentum setting in T10, in order to make cross section measurements of low energy protons in argon. To explore the energy region comparable to hadrons produced by GeV-scale neutrino interactions at oscillation experiments, i.e., near 0.1 GeV of kinetic energy, methods of moderating the T10 beam were employed: the dual technique of moderating the beam with acrylic blocks and measuring scattered protons off the beam axis was used to decrease the kinetic energy of incident protons, as well as change the proton/minimum ionising particle (MIP) composition of the incident flux. Measurements of the beam properties were made using time of flight systems upstream and downstream of the TPC. The kinetic energy of protons reaching the TPC was successfully changed from ∼0.3 GeV without moderator blocks to less than 0.1 GeV with four moderator blocks (40 cm path length). The flux of both protons and MIPs off the beam axis was increased. The ratio of protons to MIPs vary as a function of the off-axis angle allowing for possible optimisation of the detector to select the type of required particles. Simulation informed by the time of flight measurements show that with four moderator blocks placed in the beamline, (5.6 ± 0.1) protons with energies below 0.1 GeV per spill traversed the active TPC region. Measurements of the beam composition and energy are presented