Microbeam irradiation effects on transmission diamond detector

Kada, Wataru; Sato, Takahiro; Iwamoto, Naoya; Onoda, Shinobu; Grilj, V.*; Skukan, N.*; Makino, Takahiro; Koka, Masashi; Jaki, M.*; Oshima, Takeshi; Kamiya, Tomihiro

Thin film CVD diamond detector is now under investigation for the utilization as a transmission detector for ionized particle in single-ion-hit by replacing materials of the beam extraction window in a microbeam line of the AVF cyclotron at JAEA/Takasaki. In this research, a spectroscopy-grade 50 m thick-film Single Crystalline (SC) CVD diamond detector with size of 4.6 mm 4.6 mm was characterized using Ion Beam Induced Charge (IBIC) and Transient Ion Beam Induced Current (TIBIC) systems. The detector was irradiated with 1-3 MeV H and 15 MeV O microbeams. Significant decrease of pulse height of IBIC signals was observed at 15 MeV O irradiation, however, this peak degradation easily recovered in a short time by release of bias voltages. This temporal degradation effect was enhanced in areas damaged by previous ion irradiation. Therefore, the temporal peak degradation seems to be caused by the polarization effect due to charge captured by defects in diamond or/and at the surface.