Response of a dielectric microcalorimeter operating with a feed-back of detection pulse signa

微量热计通过吸收器中保持在低于1k的低温下的温升来检测单个粒子的辐射。灵敏的温度计是微热量计的重要组成部分。0.99SrTiO_3-0.01SrTa_2O_6介电材料的电容量表现出温度依赖性，且在200 mK以下具有最小值。电容量的温度依赖性可用于微量热计的敏感温度计。通过施加恒定的直流电压，电容的变化改变了储存在介电电容器中的电荷。在电介质微热量计中，入射辐射引起的温升被转换成与电介质材料电容变化成正比的电荷。由于介电微量热计没有电流流过介质器件，因此具有抑制器件中约翰逊噪声和焦耳热产生的优点。材料的电容d(ln C_d)/dT与温度的关系是介质温度计的重要参数。制备了0.99SrTiO_3-0.01SrTa_2O_6介电样品。在100mK时，介质样品的d(ln C_d)/dT的实验值为-2.02。然而，对于0.99SrTiO3-0.01SrTa2O6介电样品制成的原型温度计，其d(ln C_d)/dT值不能得到重复性。经过多次研究，发现0.99SrTiO_3-0.01SrTa_2O_6介电材料中SrO与TiO_2之间的非化学计量关系影响了d(ln C_d)/dT值在1K以下的行为。我们用0.99SrTiO_3-0.01SrTa_2O_6介电材料制作了一个介电微量热计原型。在运行无液氦的紧凑型稀释制冷机冷却至100 mK以下后，用^<241>Am源发射的α粒子照射介电微热计。电介质微热计检测到5.5 MeV的α粒子。在电荷敏感前置放大器的输出端施加110 V的偏置电压，检测信号的脉冲高度为1.6 V。在这项研究中，我们证明了电介质微热量计具有优异的检测性能。少

The microcalorimeter detects a single particle of radiation by means of the temperature rise in the absorber kept at low temperatures below 1 K. A sensitive thermometer is important component in the microcalorimeter. The electric capacitance of 0.99SrTiO_3-0.01SrTa_2O_6 dielectric materials exhibits the temperature dependence and the minimum value below 200 mK. The temperature dependence of the electric capacitance can be utilized for the sensitive thermometer of the microcalorimeter. By applying a constant DC voltage, a change in the electric capacitance alters the electric charge stored in the dielectric capacitor. In the dielectric microcalorimeter, the temperature rise induced by the incident radiation is converted to the electric charge proportional to the change in the electric capacitance of the dielectric material. Because of no current-flow across the dielectric device, the dielectric microcalorimeter has advantage of suppression of the Johnson noise and the Joule heat generat … More ion in the device. The temperature dependence of electric capacitance d(ln C_d)/dT of the material is important parameter for the dielectric thermometer. We fabricated 0.99SrTiO_3-0.01SrTa_2O_6 dielectric samples. The experimental value of d(ln C_d)/dT of the dielectric sample was -2.02 at 100mK. However reproducibility in values of d(ln C_d)/dT was not obtained for prototype thermometers made of 0.99SrTiO3-0.01SrTa2O6 dielectric samples. After several researches, the behavior of the value of d(ln C_d)/dT below 1K was found to be affected by a nonstoichiometry between SrO and TiO_2 in 0.99SrTiO_3-0.01SrTa_2O_6 dielectric materials. We fabricated a prototype dielectric microcalorimeter using 0.99SrTiO_3-0.01SrTa_2O_6 dielectric materials. After cooled down below 100 mK by operating a liquid helium-free compact dilution refrigerator, the dielectric microcalorimeter was irradiated by alpha particles emitted from ^<241>Am source. The dielectric microcalorimeter detected 5.5 MeV alpha particles. By applying the bias voltage of 110 V, the pulse height of the detection signal was 1.6 V at the output of a charge sensitive preamplifier. In this study, we demonstrated potential of excellent detection performance of the dielectric microcalorimeter. Less