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SPONTANEOUS ACCELERATION OF FREELY ROTATING HELIUM II AS A MANIFESTATION OF A NEW TYPE OF QUANTUM PHASE TRANSITION
E. Andronikashvili, J. Tsakadze, S. Tsakadze
To cite this version:
E. Andronikashvili, J. Tsakadze, S. Tsakadze. SPONTANEOUS ACCELERATION OF FREELY ROTATING HELIUM II AS A MANIFESTATION OF A NEW TYPE OF QUANTUM PHASE TRANSITION. Journal de Physique Colloques, 1978, 39 (C6), pp.C6-180-C6-181.
�10.1051/jphyscol:1978680�. �jpa-00218360�
JOURNAL DE PHYSIQUE
Colloque C6, supplgment au no 8, Tome 39, aoiit 1978, page C6-180
SPONTANEOUS ACCELERATION OF FREELY ROTATING HELIUM I 1 A S A MANIFESTATION OF A NEW T Y P E OF QUANTUM PHASE T R A N S I T I O N *
E.L. Andronikashvili, J . S . Tsakadze and S . J . Tsakadze.
I n s t i t u t e o f P h y s i c s , Adademy o f S c i e n c e s o f t h e Georgian SSR, T b i l i s i , U.S.S.R.
Rbsum6.- On montre expbrimentalement que dans 1'He I1 e n r o t a t i o n "auto-accblbrbe", l e r 6 s e a u de l i g n e s de v o r t e x prLsente une i n s t a b i l i t b .
Abstract.- New experiments on r o t a t i n g He I1 d i s p l a y a jump-like change i n t h e number of v o r t i c e s and i n the v o r t e x l a t t i c e c o n s t a n t .
During t h e i n v e s t i g a t i o n of t h e p r o p e r t i e s of the r o t a t i n g helium we have d i s c o v e r e d and thorou- ghly s t u d i e d a t our l a b o r a t o r y /I-8/ the a b i l i t y of t h i s l i q u i d t o r e t a i n t h e s t a t e of m e t a s t a b l e r o t a - t i o n ( t h e absence of v o r t i c e s i n helium 11, presence of q u a n t i z e d v o r t i c e s i n helium I, e t c ) f o r a l a n g time.
This f a c t suggested an i d e a t o E.L. Andronikashvili and J.S. Tsakadze / 9 / t h a t t h e formation o r decay of v o r t i c e s may r e p r e s e n t t h e phase t r a n s i t i o n of t h e f i r s t o r d e r (accompanied by t h e a b s o r p t i o n o r r e l e a s e of energy e q u a l t o t h e t o t a l energy of t h e formed o r decayed v o r t i c e s ) . However, t h i s p o i n t of view could n o t be confirmed on t h e b a s i s of t h e mea-
surements of t h e r o t a t i n g l i q u i d helium d e n s i t y . N e v e r t h e l e s s , we should r e t u r n t o t h e problem of t h e n a t u r e of t h e phenomena observed i n r o t a t i n g l i q u i d helium t a k i n g i n t o account our new experimen- t a l r e s u l t s .
We have a l r e a d y r e p o r t e d a p e c u l i a r phenome- non - t h e s e l f - a c c e l e r a t i o n of t h e v e s s e l f i l l e d w i t h helium I1 r o t a t i n g with small slow down / l o / . It should be r e c a l l e d t h a t i n t h i s work we have used a c y l i n d r i c a l v e s s e l suspended i n t h e magnetic f i e l d w i t h o u t a s u p p o r t . The v e s s e l was f i l l e d w i t h l i q u i d helium and r o t a t e d i n helium vapors above t h e l e v e l of t h e l i q u i d i n a c r y o s t a t . The r e c o r d i n g of t h e r o t a t i o n r a t e was r e a l i z e d by t h e system c o n s i s t i n g of a p h o t o s e n s i t i v e element and an e l e c t r i c c i r c u i t connected t o t h e computer c o n t r o l l i n g t h e f i x a t i o n and t r e a t m e n t of t h e experimental r e s u l t s . A f t e r t h e i n i t i a l a c c e l e r a t i o n r e a l i z e d by t h e asynchronous e l e c t r o m o t o r with r o t o r a x i a l l y f i x e d t o t h e v e s s e l , the a p p a r a t u s could r o t a t e f o r h o u r s , smoothly slowing down due t o f r i c t i o n a g a i n s t t h e s a t u r a t e d
helium vapor. A more d e t a i l e d d e s c r i p t i o n of t h e a p p a r a t u s i s given i n t h e paper / 1 1 / . The c y l i n d r i - c a l v e s s e l w i t h a h e i g h t of 70 mm, i n n e r diameter of 15 rnm and w a l l t h i c k n e s s of 0.15 mm was made of p l e x i g l a s .
We have r e p e a t e d l y observed t h e c a s e s of sponta- neous a c c e l e r a t i o n of t h e a p p a r a t u s f i l l e d w i t h he- lium I1 a f t e r a r a t h e r long p e r i o d s i n c e t h e begin- ning of r o t a t i o n ( a s was p a r t i a l l y r e p o r t e d i n t h e paper of J . Tsakadze and S . Tsakadze / 1 2 / ) . The mea- surements were c a r r i e d o u t a t T = 1.46 K. The por- t i o n of t h e curve of t h e dependence of t h e r o t a t i o n r a t e l o g a r i t h m of on time t corresponding t o spon- taneous a c c e l e r a t i o n of t h e a p p a r a t u s i s shown i n f i g u r e 1 .
F i g . 1 : Time dependence of t h e l o g a r i t h m of a n g u l a r v e l o c i t y of f r e e l y r o t a t i o n v e s s e l f i l l e d w i t h He I1 (w' = 1.2713
s-'1'
We e x p l a i n t h e phenomenon of s e l f i - a c c e l e r a t i o n of Helium I1 f r e e l y r o t a t i n g a t a low f r i c t i o n , a s a r e s u l t of simultaneous disappearance of a l a r g e number of v o r t i c e s , t h e moment of momentum of which i s t r a n s f e r r e d t o t h e v e s s e l . I n o t h e r words, a t t h e a n g u l a r v e l o c i t y a t which s e l f - a c c e l e r a t i o n of t h e r o t a t i n g l i q u i d t a k e s p l a c e , v o r t e x l a t t i c e i s i n a m e t a s t a b l e s t a t e i n which t h e d e n s i t y of v o r t i c e s exceeds t h e d e n s i t y which should correspond t o t h e given v e l o c i t y of t h e v e s s e l . This " o v e r s a t u r a t i o n "
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1978680
amounts t o 2, 5 %.
The jump-like change of t h e number of v o r t i c e s i s accompanied by a jump-like change of t h e v o r t e x l a t t i c e c o n s t a n t . S i m u l t a n e o u s l y , t h e phenomenologi- c a l wave f u n c t i o n Y d e s c r i b i n g t h e s t a t e of t h e con4 d e n s a t e a l s o changes i n a jump-like way.
T h i s phenomenon can be c o n s i d e r e d a s a s p e c i a l t y p e of quantum phase t r a n s i t i o n . Helium I1 i s known t o be a c o h e r e n t macroscopic system which may be des- c r i b e d by a s i n g l e - p a r t i c l e wave f u n c t i o n 'f'(r,t). -3- At e q u i l i b r i u m r o t a t i o n w i t h two d i f f e r e n t v e l o c i t i e s we d e a l w i t h two d i f f e r e n t s t a t e s d e s c r i b e d by d i f - f e r e n t f u n c t i o n s Y and'4 which d i f f e r from one
fll fl2
a n o t h e r by t h e i r e i g e n v a l u e s of t h e moment of t h e l1 and 12. S i n c e i n o u r c a s e t h e t r a n s i t i o n from s t a t e l1 i n t o s t a t e l 2 i s jump-like, t h e p r o c e s s un- d e r c o n s i d e r a t i o n i s a phase t r a n s i t i o n . I n t h e r e - view /13/ t h i s c o n d i t i o n i s d e m o n s t r a t e d by means of a phenomenological wave f u n c t i o n . Even i f a s i n g l e v o r t e x i s formed i n r o t a t i n g h e l i u m 11, a phase t r a n - s i t i o n t a k e s p l a c e . The phase diagram o f r o t a t i n g h e l i u m I1 f o r t h e f o l l o w i n g s t a t e s : w i t h o u t v o r t i c e s w i t h a s i n g l e v o r t e x , two v o r t i c e s e t c , i s d e s c r i b e d i n r e v i e w / 1 3 / . I n t h e p r e s e n t c a s e we come a c r o s s a phase t r a n s i t i o n of q u i t e a new t y p e . T h i s p h a s e t r a n s i t i o n of q u i t e a new t y p e . T h i s phase t r a n s i - t i o n i s connected w i t h jump-like change of t h e t o t a l number of v o r t i c e s and t h e . l a t t i c e c o n s t a n t ( t h e d i s -
t a n c e betwee; v o r t i c e s ) . T h i s phenomenon i s e n t i r e l y new a s t h e phase t r a n s i t i o n t a k e s p l a c e n o t i n t h e system of atoms o r m o l e c u l e s b u t i n t h e system of v o r t i c e s , e a c h of them i n v o l v i n g i n t o i t s moment a macroscopic number o f h e l i u m atoms. As i t was n o t e d a above, t h e t r a n s i t i o n i s c h a r a c t e r i z e d by t h e pos- s i b i l i t y o f f o r m a t i o n of m e t a s t a b l e s t a t e s and l a r - ge r e l a x a t i o n t i m e s .
I t s h o u l d be p o i n t e d o u t t h a t i n t h e l i g h t of t h e s t a t e d f a c t s and t h e i r i n t e r p r e t a t i o n t h e pro- blem of t h e phase t r a n s i t i o n c h a r a c t e r i n r o t a t i n g h e l i u m 1-1 s h o u l d be c o n s i d e r e d e x c l u s i v e l y from t h e quantum mechanical p o i n t of view.
I n c o n c l u s i o n i t s h o u l d be mentioned t h a t ac- c o r d i n g t o Packard h y p o t h e s i s /14/ t h e decay of me- t a s t a b l e v o r t i c e s may c a u s e t h e a c c e l e r a t i o n of p u l - s a r s , which i s u s u a l l y a t t r i b u t e d t o s t a r q u a k e s . Our e x p e r i m e n t s e x p l i c i t l y c o n f i r m t h e v a l i d i t y of t h i s p o i n t of view. I n c a s e of a s t a r q u a k e f i r s t t h e h a r d s h e l l of p u l s a r and t h e n t h e s u p e r f l u i d n e u t r o n li- q u i d a r e a c c e l e r a t e d , w h i l e i n t h e c a s e of t h e decay of m e t a s t a b l e v o r t i c e s t h e a c c e l e r a t i o n of t h e s h e l l
f o l l o w s t h e a c c e l e r a t i o n o f t h e l i q u i d . It i s c l e a r t h a t i n t h e f i r s t c a s e a c c e l e r a t i o n i s s h a r p e r and r e l a x a t i o n i s l o n g e r t h a n i n t h e second c a s e . There i s i n d i c a t i o n i n l i t e r a t u r e t h a t one of t h e o b s e r - ved a c c e l e r a t i o n s of t h e Crab n e b u l a p u l s a r d i f f e r s from i t s o t h e r a c c e l e r a t i o n s b o t h by t h e s h a p e of t h e a c c e l e r a t i o n c u r v e and by t h e d u r a t i o n o f r e l a - x a t i o n p r o c e s s e s / 1 5 / . It i s p o s s i b l e t h a t d u r i n g
t h i s v e l o c i t y jump t h e a c c e l e r a t i o n a s s o c i a t e d w i t h t h e decay of m e t a s t a b l e v o r t i c e s was r e a l i z e d .
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