Evidence of delayed light emission of TetraPhenyl Butadiene excited by liquid Argon scintillation light
Evidence of delayed light emission of TetraPhenyl Butadiene excited by liquid Argon scintillation light
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液态氩闪烁光激发四苯基丁二烯延迟发光的证据
DOI：
10.1103/physrevc.91.035503
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发表时间：
2014
影响因子：
3.1
通讯作者：
E. Segreto
中科院分区：
文献类型：
--
作者：
E. Segreto
四苯基丁二烯是与液态氩结合使用最广泛的波长移动器。后者发射波长为127 nm的闪烁光子，需要将其下移以通过具有玻璃或石英窗的光电倍增管检测。四苯基丁二烯已被证明具有极高的转换效率，对于127 nm光子可能高于100%，而没有关于其发射的时间依赖性的精确信息。它通常被假定为指数衰减的一个特征时间的顺序为一纳秒，作为一个外推从测量激发辐射在近紫外线。这项工作表明，四苯基丁二烯，当激发127 nm的光子，重新发射光子不仅具有非常短的衰减时间，但也与较慢的，由于三重态去激发。这一事实可以有力地有助于澄清自20世纪70年代以来文献中报道的液氩闪烁光的异常，即长衰变时间常数的测量值的不一致性和中间组分的出现。当TPB与氦和氖结合使用时，也应该预期类似的效果，氦和氖发射波长短于127 nm的闪烁光子。
Tetraphenyl-butadiene is the wavelength shifter most widely used in combination with liquid argon. The latter emits scintillation photons with a wavelength of 127 nm that need to be downshifted to be detected by photomultipliers with glass or quartz windows. Tetraphenyl-butadiene has been demonstrated to have an extremely high conversion efficiency, possibly higher than 100% for 127 nm photons, while there is no precise information about the time dependence of its emission. It is usually assumed to be exponentially decaying with a characteristic time of the order of one ns, as an extrapolation from measurements with exciting radiation in the near UV. This work shows that tetraphenyl-butadiene, when excited by 127 nm photons, re-emits photons not only with a very short decay time, but also with slower ones due to triplet states de-excitations. This fact can strongly contribute to clarifying the anomalies in liquid-argon scintillation light reported in the literature since the 1970s, namely, the inconsistency in the measured values of the long decay time constant and the appearance of an intermediate component. Similar effects should be also expected when the TPB is used in combination with helium and neon, which emit scintillation photons with wavelengths shorter than 127 nm.