本文报告了一个用塑料闪烁体环探测器作反符合屏蔽的NaI(T_1)γ能谱仪的结构及主要性能。它采用Φ76×76mmNaI(Tl)晶体作为主探测器和符合探测器,以自制的Φ500×520mm塑料闪烁体作环探测器。在有无井型反符合屏蔽条件下,能量范围0.1—2MeV时,谱仪的积分本底比为2.8,对~(137)Csγ源的康普顿减弱因子(积分比)为2.5。当源位于晶体表面中心时,谱仪对~(137)Cs源的能量分辨率和全能峰效率分别为9.5％和8.4％。 This paper reports the structure and main properties of a NaI (T_1) gamma spectrometer with a plastic scintillator ring detector for anti-coincidence shielding. It uses Φ76 × 76mmNaI (Tl) crystal as the main detector and coincides with the detector, with a homemade Φ500 × 520mm plastic scintillator ring detector. In the presence or absence of well-type anti-conforming shielding, the integral background ratio of the spectrometer was 2.8 for the energy range of 0.1-2 MeV and the Compton Abatement Factor (integral ratio) for 137 Csγ sources was 2.5. When the source is located at the center of the crystal surface, the energy resolution and the all-purpose peak efficiency of the spectrometer to the source of 137 Cs are 9.5% and 8.4%, respectively.