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Register a new userAn experiment of X-ray photon-photon elastic scattering with a Laue-case beam collider
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We report a search for photon-photon elastic scattering in vacuum in the X-ray region at an energy in the center of mass system of omega_{cms} =6.5 keV for which the QED cross section is sigma_{QED} =2.5 times 10^{-47} m^2. An X-ray beam provided by the SACLA X-ray Free Electron Laser is split and the two beamlets are made to collide at right angle, with a total integrated luminosity of (1.24 pm 0.08) times 10^{28} m^{-2}. No signal X rays from the elastic scattering that satisfy the correlation between energy and scattering angle were detected. We obtain a 95% C.L. upper limit for the scattering cross section of 1.9 times 10^{-27} m^2 at omega_{cms}=6.5 keV. The upper limit is the lowest upper limit obtained so far by keV experiments.
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Single crystals have high atomic electric fields as much as 10^{11} V/m, which correspond to magnetic fields of sim 10^3 T. These fields can be utilized to convert X rays into Axion Like Particles (ALPs) coherently similar to X-ray diffraction. In this paper, we perform the first theoretical calculation of the Laue-case conversion in crystals based on the Darwin dynamical theory of X-ray diffraction. The calculation shows that the Laue-case conversion has longer interaction length than the Bragg case, and that ALPs in the keV range can be resonantly converted by tuning an incident angle of X rays. ALPs with mass up to O(10 keV) can be searched by Light-Shining-through-a-Wall (LSW) experiments at synchrotron X-ray facilities.
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L. I. Shekhtman
, V. I. Telnov (Institute of Nuclear Physics andn Novosibirsk State Univ.
, Novosibirsk
2014
Photon beams at photon colliders are very narrow, powerful (10--15 MW) and cannot be spread by fast magnets (because photons are neutral). No material can withstand such energy density. For the ILC-based photon collider, we suggest using a 150 m long, pressurized (P ~ 4 atm) argon gas target in front of a water absorber which solves the overheating and mechanical stress problems. The neutron background at the interaction point is estimated and additionally suppressed using a 20 m long hydrogen gas target in front of the argon.
In the Deep Underground Neutrino Experiment (DUNE), the VUV LAr luminescence is collected by light trap devices named X-Arapuca, sizing (480x93) mm2. Six thousand of these units will be deployed in the first DUNE ten kiloton far detector module. In this work we present the first characterization of the photon detection efficiency of an X-Arapuca device sizing (200x75) mm2 via a complete and accurate set of measurements along the cell longitudinal axis with a movable 241-Am source. The MPPCs photosensors are readout by a cryogenic transimpedance amplifier to enhance the single photoelectron sensitivity and improve the signal-to-noise while ganging 8 MPPC for a total surface of 288 mm2. Moreover we developed a new photon downshifting polymeric material, by which the X-Arapuca photon detection efficiency was enhanced of about +50% with respect to the baseline off-shell product deployed in the standard device configuration. The achieved results are compared to previous measurements on a half size X-Arapuca device, with a fixed source facing the center, with no cold amplification stage, and discussed in view of the DUNE full size optical cell construction for both the horizontal and the vertical drift configurations of the DUNE TPC design and in view of liquid Argon doping by ppms of Xe. Other particle physics projects adopting Liquid Argon as target or active veto, as Dark Side and LEGEND or the DUNE Near Detector will take advantage of this novel wavelength shifting material.
We report the first results of a search for real photon-photon scattering using X rays. A novel system is developed to split and collide X-ray pulses by applying interferometric techniques. A total of $6.5times10^{5}$ pulses (each containing about $10^{11}$ photons) from an X-ray Free-Electron Laser are injected into the system. No scattered events are observed, and an upper limit of $1.7times 10^{-24}$ ${rm m^{2}}$ (95% C.L.) is obtained on the photon-photon elastic scattering cross section at 6.5 keV.
We present a new experimental method for measuring the process of Coherent Elastic Neutrino Nucleus Scattering (CENNS). This method uses a detector situated transverse to a high energy neutrino beam production target. This detector would be sensitive to the low energy neutrinos arising from pion decays-at-rest in the target. We discuss the physics motivation for making this measurement and outline the predicted backgrounds and sensitivities using this approach. We report a measurement of neutron backgrounds as found in an off-axis surface location of the Fermilab Booster Neutrino Beam (BNB) target. The results indicate that the Fermilab BNB target is a favorable location for a CENNS experiment.
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