Search for Decay Rate Variation of 7Be in Pt and Al

Online The decay rate variation of r Be implanted into platinum and aluminum host materials has been measured via detecting the 478 keV γ-rays from the first excited state of r Li populated in the electron capture decay of7r Be. The result （λpt - λA1）λ0 = （-0.17 ± 0.13）% is obtained. It is smaller than the theoretical estimate from the TB-LMTO calculation （0.38%）. This is quite different from our previous study which showed a 1arger decay rate variation （（0.8 ± 0.2）%） than the TB-LMTO calculation （0.30%） of 7 Be in palladium and gold. It is suggested that the effective quasi-free electron density near the implanted ions in different metal host materials may play an important role in r Be EC decay rate variation in addition to the electronic affinity and crystal structure of different host materials.