Table 2.

Activity of the main contaminants in the materials considered for the COSINUS setup. Secular equilibrium is assumed for the decay chains. The rightmost column states the neutron yield due to $(\alpha ,n)$ and spontaneous fission reactions attained using the SOURCES4C code [25]

Material	${}^{238}$U	${}^{235}$U	${}^{232}$Th	Ref.	${}^{40}$K	${}^{60}$Co	${}^{137}$Cs	Ref.	Neutron yield
	(mBq/kg)	(mBq/kg)	(mBq/kg)		(mBq/kg)	(mBq/kg)	(mBq/kg)		(cm${}^{-3}$ s${}^{-1}$)
Stainless steel	$<0.2$	–${}^{\ast }$	$<0.1$	[30]	$<5.2$	1.9	$<0.6$	[31]	$3.0·{10}^{-12}$
Pb	$<0.01$	–${}^{\ast }$	$<0.07$	[30]	–	–	–	–	$1.2·{10}^{-13}$
Cu	$<0.065$	–${}^{\ast }$	$<0.002$	[32]	$<0.34$	0.21	$<0.03$	[31]	$6.6·{10}^{-13}$
PE	$<3.8$	$<0.37$	$<0.14$	[33]	0.7	$<0.1$	0.06	[33]	$9.4·{10}^{-12}$

${}^{\ast }$no measured value given, natural abundance assumed