Physics Seminar DATE: 2012-12-07 16:00 - 17:00 PLACE: Tsukuba Campus building No.4 room#345 TITLE: physics seminar / Reactor theta_13; the Ultimate Measurement? CONTACT: Takasumi Maruyama SPEAKER: Pau NOVELLA  (Marie Curie Fellow/CNRS-APC, Paris) LANGUAGE: English ABSTRACT: A new neutrino oscillation mode has been observed in around 2011-2012 by reactor neutrino experiments. This oscillation mode was expected under the 3 neutrino oscillations model characterised by the PMNS mixing leptonic flavour matrix , where the so-called "solar" and "atmospheric" modes are modulated by the the mixing angles θ12 and θ23, respectively. The new oscillation is modulated by θ13. Amazing progress has been obtained thanks to the precise contributions of the reactor neutrino experiments (alphabetically ordered: Daya Bay, Double Chooz, RENO). Consistent evidence towards θ13 oscillations had been obtained from electron neutrino appearance by T2K and MINOS experiments and the tension between combined Solar experiments and KamLAND results. sin^2(2θ>13) is now known to be around 0.1 -as large as the CHOOZ limit allowed it to be- while the current precision is around 15%, dominated by the Daya Bay measurements. In this seminar, the global reactor θ13 measurement situation will be reviewed. The final best reactor θ13 measurement (full statistics envisaged by end of ~2015) will dominate our knowledge on this parameter for a long time. No other technique, with current technologies, is expected to offer cleaner input on the value of θ13. We will cover discussion on the experimental progress to ensure a precise but also the most accurate measurement of θ13. The impact of the accuracy on the knowledge of θ13 will be highlighted within the phenomenological context of a coherent 3-neutrino oscillation model. Back