High voltage capacitors for low background experiments

Abstract

Low background experiments place stringent constraints on amount of radioactive impurities in the materials used for their assembly. Often these are in conflict with the constraints placed on the materials by their roles in the experiment. This is especially true for certain electronic components. A high value, high voltage capacitor for use in low background experiments has been developed from specially selected radiopure materials. Electroformed copper foils are separated by polyethylene napthalate (PEN) foils and supported within a PTFE teflon spiral coil tube. The electrical performance as well as radiopurity are scrutinized here. With some minor modifications to tune the performance for the application, this capacitor can be well suited for a variety of applications in low background experiments. Here the use of the capacitor for high voltage (HV) decoupling in the operation of high purity germanium (HPGe) detectors is demonstrated.

Use of poly(ethylene naphthalate) as a self-vetoing structural material

“…Radiopurity screening was performed at the Gran Sasso National Laboratory (LNGS). The results of these measurements together with earlier screening results of Teonex Q51 film [6] and a laminate produced on PEN film [7] are shown in Tab. 1.…”

“…1. The earlier results are from two experiments where PEN has been chosen for its radiopurity, where it was used as low-background signal links for the CUORE experiment [10], and for the production of HV capacitors for the GERDA experiment [6]. According to the LNGS results, the pellet samples have a much higher 40 K contamination compared to the Teonex Q51 foil, which is suspected to be due to surface contamination of the pellets; therefore, a new screening campaign is ongoing for a new batch of TN-8065S.…”

Use of poly(ethylene naphthalate) as a self-vetoing structural material

“…Radiopurity screening was performed at the Gran Sasso National Laboratory (LNGS). The results of these measurements together with earlier screening results of Teonex Q51 film [6] and a laminate produced on PEN film [7] are shown in table 1. The earlier results are from two experiments where PEN has been chosen for its radiopurity, where it was used as low-background signal links for the CUORE experiment [10], and for the production of HV capacitors for the GERDA experiment [6].…”