PoS(INTEGRAL 2010)113 The X-ray polarimeters on-board the NHXM mission Fabio Muleri *a , Ronaldo Bellazzini b , Alessandro Brez b , Enrico Costa a , Sergio Di Cosimo a , Sergio Fabiani a,c , Francesco Lazzarotto a , Massimo Minuti b , Michele Pinchera b , Paolo Sofﬁtta a and Gloria Spandre b a INAF/IASF Rome Via del Fosso del Cavaliere 100, I-00133 Rome, Italy b INFN Pisa Largo B. Pontecorvo 3, I-56127 Pisa, Italy c Università di Roma Tor Vergata, Dipartimento di Fisica via della Ricerca Scientiﬁca 1, 00133 Rome, Italy E-mail: fabio.muleri@iasf-roma.inaf.it The New Hard X-ray imaging and polarimetric Mission (NHXM) makes a synergic use of broad band spectroscopy (0.3-80 keV, 120 keV goal) and polarimetry (2-35 keV) as complementary di- agnostics of the same astrophysical systems. Here we describe the polarimeters on-board NHXM. Two Gas Pixel Detectors, ﬁlled with different mixtures which are based on Helium and Argon, are placed alternatively in the focus of one out of the four telescopes. The instruments are sensitive in the 2-10 keV (LEP, Low Energy Detector) and 6-35 keV (MEP, Medium Energy Detector) energy bands. The performance is comparable, with a Minimum Detectable Polarization at 99% conﬁ- dence level of 9.7% (LEP) and 13% (MEP) for a 1 mCrab source and an observation lasting 100 ks. Spectroscopy with moderate resolution (20% at 6 keV) and timing (8 μ s) will be performed contemporaneously to polarimetry. Unique capabilities among next mission of X-ray polarimetry is the possibility to image the source with an angular resolution which basically is that of the optics, about 15-20 arcseconds, and to extend the energy band above 10 keV. 8th INTEGRAL Workshop “The Restless Gamma-ray Universe”- Integral2010, September 27-30, 2010 Dublin Ireland * Speaker. c  Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/