  The B-mode detection of Cosmic Microwave Background polarization will require
new technological developments, able to get sensitivities at least 2 orders of
magnitude better than for the E-mode. This really ambitious goal cannot be
reached simply by either improving the present technology or by adding more
detectors to current design, at least in the frame of having a new space
mission operating within a decade. Thus, the scientific community have to take
important decisions about the most suitable technologies on which converge the
needed effort. Basically, at present two receiver families do exist: bolometric
and radiometric. Both of them are continuoulsly improving their basic
performances, but the optimal approach to B-modes may require some decisions
have to be taken in short time scale. In any case, radiometric and bolometric
receivers have to deal with some common sources of systematics as well as they
both require some cryogenics. Thus, we should expect that systematics and
cryogenics may play as watershed line in designing future experiments aimed at
measuring the B-mode of Cosmic Microwave Background.
