Observation of a J^PC = 1-+ exotic resonance in diffractive dissociation of 190 GeV/c pi- into pi- pi- pi+

The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the pi- pi- pi+ final state using a 190 GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1 GeV^2/c^2. The well-known resonances a1(1260), a2(1320), and pi2(1670) are clearly observed. In addition, the data show a significant natural parity exchange production of a resonance with spin-exotic quantum numbers J^PC = 1-+ at 1.66 GeV/c^2 decaying to rho pi. The resonant nature of this wave is evident from the mass-dependent phase differences to the J^PC = 2-+ and 1++ waves. From a mass-dependent fit a resonance mass of 1660 +- 10+0-64 MeV/c^2 and a width of 269+-21+42-64 MeV/c^2 is deduced.Comment: 7 page, 3 figures; version 2 gives some more details, data unchanged; version 3 updated authors, text shortened, data unchange

Exploring Cosmic Origins with CORE: Survey requirements and mission design

Future observations of cosmic microwave background (CMB) polarisation havethe potential to answer some of the most fundamental questions of modernphysics and cosmology. In this paper, we list the requirements for a future CMBpolarisation survey addressing these scientific objectives, and discuss thedesign drivers of the CORE space mission proposed to ESA in answer to the "M5"call for a medium-sized mission. The rationale and options, and themethodologies used to assess the mission's performance, are of interest toother future CMB mission design studies. CORE is designed as a near-ultimateCMB polarisation mission which, for optimal complementarity with ground-basedobservations, will perform the observations that are known to be essential toCMB polarisation scienceand cannot be obtained by any other means than adedicated space mission

On-line mirror alignment monitoring method for COMPASS RICH-1 RID D-9840-2011

COMPASS RICH-1 is a large size gaseous Cherenkov detector. Two reflecting spherical surfaces, covering a total area of about View the MathML source21m2 hosted in the radiator vessel provide image focusing. The segmented surfaces are formed by 116 mirrors, with individual degrees of freedom for angular adjustment. An original method has been developed and applied for the on-line monitoring of the mirror alignment. Relative tilts between neighbouring mirror elements create discontinuities in the image of continuous lines reflected by the mirror wall. The measurement of the discontinuities can also provide information about the absolute tilt with a resolution of 0.1 mrad. An independent check and calibration of this method has been performed in laboratory using, as reference, a laser interferometer. We present the technical solutions adopted to implement the dedicated setup, the results of the method calibration by laser interferometer, and the preliminary results obtained measuring the alignment of the RICH-1 mirror wall