A new surface laboratory for measurements of low-level radioactivity.

A laboratory for measuring low-level radioactivity has been built at the AlbaNova University Center in Stockholm. Low-level concrete in combination with a 5 cm iron lining provide an average photon fluency rate from terrestrial sources at least a factor of 40 below that in the common laboratories of the Center. The radon activity inside the laboratory has been measured to (3+/-2) Bq m(-3).

Inclusion of electric octupole contributions explains the fast radiative decays of two metastable states in Ar+.

A laser probing investigation has yielded the lifetimes of the 3s(2)3p(4)(1D)3d (2)G(7/2,9/2) metastable doublet states of Ar+. The results, obtained with the CRYRING ion storage ring of Stockholm, are 3.0+/-0.

Importance of an M2 depopulating channel for a Kr II metastable state.

An experimental investigation of the radiative lifetime of the metastable 4s24p4(3P)4d4D7/2 level in Kr II shows an unusual situation regarding the importance of an M2 depopulation channel. While the first order M1 and E2 channels are expected to contribute in a dominant way to the decay, the experimental result, obtained using a laser probing technique on a stored ion beam, tau = 0.57+/-0.

Lifetime measurements of metastable states in Fe+.

The lifetime of two metastable levels in Fe+ has been measured by laser probing of a stored ion beam. In the dense spectrum of Fe+, the metastable levels a (6)S(5/2) and b (4)D(7/2) were selected and their lifetimes were determined to be 230 +/- 30 and 530 +/- 30 ms, respectively. The lifetimes are compared with previous theoretical results.