Review Article
Challenges in Double Beta Decay
| | GERDA-I | Ge ( = 2039 keV) running |
| | FWHM | 4 keV | | EXPOSURE | 21.6 kg × yr | | MASS | 13.5 kg of Ge, only 10.9 used for this result (18 kg coaxial HPGe + 3.6 kg BEGe) | | BKG | | | Rejection | Single-site versus multisite events separation | | Rate | × 10−2 counts/(keV·kg·yr) on coaxial HPGe (with PSA) | | | × 10−2 counts/(keV·kg·yr) on BEGe (with PSA) | | Sources | K and Rn in LAr + Bi and Th in detector assembly + surface 's | | >2.1 × 1025 yr at 90% C.L. (in the Bayesian case >1.9 × 1025 yr) |
| | GERDA-II | Ge ( = 2039 keV) upgrade of GERDA-I, under construction |
| | FWHM | 3-4 keV | | MASS | 30 kg of Ge (18 kg coaxial HPGe + 21 kg BEGe) | | BKG | | | Rejection | Single-site versus multisite events separation | | Goal | 10−3 counts/(keV·kg·yr) (design value with PSA) | | 6.0 × 1026 yr in 5 years (optimistic: assuming zero background condition reached on both coaxial and BEGe detectors and detection efficiency of 66%) | | 2.2 × 1026 yr in 5 years (conservative approach: assuming the best background counting rate measured by GERDA-I and detection efficiency of 83%) |
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