A proton‐recoil telescope with thin polyethylene radiator has been designed for neutron spectroscopy and for neutron detection with known efficiency in the energy region from about 2 to 20 Mev. Five radiator thicknesses may be chosen over this energy region. Protons recoiling near zero degrees from the radiator pass through two proportional counters and terminate in a NaI(Tl) crystal. Triple coincidences gate an analyzer for observing the spectrum from the crystal. A spectrum of 13.7‐Mev neutrons was observed with a width at half‐maximum of 5.3&percent; and 6&percent; background. The efficiency with this resolution at 13.7 Mev is 3.6×10−6.