Calorimetry of Heavy Charged Particle by Superconducting Transition-Edge Sensor

Heavy ion cancer therapy allows the tumors to destroy while sparing surrounding, healthy tissues. By controlling the incident energy of heavy ions, the penetration depth can be adjusted precisely to the tumor area. The ionizing chambers are usually used for the determination of absorbed dose in the heavy ion irradiation fields; however, uncertainty in measurement of these detectors is expected to remain by more than 5%, and this has a negative influence on the therapeutic effect. Now we began to develop the precision heavy ion beam detector applying the superconducting transition-edge sensor (TES). Using the Ir/Au-TES coupled to a tin absorber, we have succeeded to detect the helium ions which were injected from Heavy Ion Medical Accelerator in Chiba. Although pulses are fully saturated because the temperature change is beyond the transition region, the signal length reflects the incident energy of each injected heavy ion. These results indicate the possibility of the precision heavy ion energy detection applying the TES detector.