A low-loss, ultrahigh vacuum compatible helium cryostat without liquid nitrogen shield

An ultrahigh vacuum compatible compact helium cryostat with a 48 h hold tim e for a 2.5 l of liquid helium capacity has been realized. The design explo its the large enthalpy of the gas phase helium, by using two layers of vapo r-cooled radiation shield in place of the conventional liquid nitrogen jack et. The mechanical rigidity, the absence of liquid nitrogen bubbling, and a low helium boil-off rate make this cryostat particularly suitable for appl ications that require a low vibration environment such as scanning probe mi croscopy. (C) 2001 American Institute of Physics.