Experimental study of the X transition in helium in narrow gaps
Panov V.I., Sobyanin A. A.
Quantitative measurements of the temperature shift of the λ transition in liquid 4He contained in thin plane parallel gaps with well controlled geometry and thickness 0.28 <d <0.54//m were performed. The value of the critical index η = 1.58 ±0.09 characterizing the dependence of the temperature shift of the Я point on the gap thickness, ΔΤλ =Ad~nf is determined. The average value of the unknown parameter Μ =0.6±0.3, contained in the phenomenological Ψ theory of superfluidity of helium II, is calculated near the Я point from the results obtained for the coefficient A.