subpage of Proceedings/ICCF-6
Cold Fusion and Electrophyslcal Processes In Ferroelectric Deuterated Crystal Is. Influence of Therml Neutron
BackgroundLeve1, D—H Substitution and Crystal Mass
A.G. Lipson, V. A. Kuz,netsov, T). M. Sakov, E.T. Saunin
Insti Lute of Physical Chemistry,
The Russian Academy of Sciences, Moscow 1 17915 Russia
Abs trac t
C’,hange i n neutron flux i ntensity upon the passing through K(D H ) PO crystals in the vicinity of Curie point depending
on thermal neutron background level , its mass and D—H substi tution index (x) has been studied. The semi —empi ri cal equi tinn that descri bes neutron emission processes in DKDP crystals near Tc quite c.orrec.tly, has been proposed.
I . Tntr•oduc tion
As i t was shown earl ier [ 1—3], upon the transi t ion through Curie point in crystals (DKDP) with x-0.98; 0.96 and 0.80 at the condi ti ons of external. thermal neutron bac.kground irradiation, the excess emission of fast neutron is observed. Tn common case it may be amplification or attenuation of external thermal neutron flux passing through crys tal in the vicini ty of Curie point. As result emission of neutron in these crystals can get posi Live or negative sign (with subtraction of background value) . Simul taneously in DKDP crystals the suppression of spontaneous deformati on, de and cracks forma ti on ara observed. In present work we will demonstrate that absolute value of neutron emission and i ts sign ( posi tive or negative one) is depend upon external thermal neutron flux, crystal mass and i ts substi tution degree-
2. Experimental part
The samples consisted of tri c single crys taLs or with x=O.96 and 1=0.80. Their Curie points are T =219 K and T = 190 K in accordance wi til calocyme tric
measurments. Samples wi th mass from g up to 11.0 g were cut from single—crys tal I ine plate in (001 ) direc temperature posi tion and polarization reversal or ferroelec. phase transi tion were moni tored by the registration of pirocurrent signals in the non—polarized samples near T with the
help thermostimulated depolari sation (TSD) technique. The samples were heated and cooled in a linear regime at a rate of O. 15 K/s.
To determine change in a neutron flux and to create flux of thermal neutron>59ne the experimental set up shown in A 1 has source of neutrons with intensi ty ‘ 200 n/s in solid angle of 4 was used for experiments with neutron of different intensi ty- The source was p] aced at a distance —6
cm from the surface of •the sarnpie, which in turn was located at a distance r cm from the neutron detector. The change in detector’s neutron background (N ) was reached by change in free
space vol ume insi de the PE box (addi on or remova of “neutrostop t• bl ocks). Measurements show, that irr the range of neutron detector background values of ISNx/N ‘270 (where M is
a detector counts for a cosmic neutron background) the ux of thermal neutron passing through I)KDP cr•ysæal is in a range of O. 1ST sP5 n/s*crn (where T —O. I n/s*cm cosmi c background
Typical results of taneous measurmerlt,s of a neutron ernissiTM1 and ‘TSD in DKDP crystals with x=O. 96 and x=O.80 are shown in fig. 2, 3. Tn the case of DKDP with 1=0.96 rn=2 g (fig. Pa) at background TX/ T = 100 the amp I i ti cati on of neutron emi ssi on
intensity ( AN) has place. The emi ssion intensi ty i s about of 20 ti mes more than for crystal temperature cyc led in the cosmic background condi t ions. Moreover i n the TSD spectrum the changes are observed, that indicate on change in domain structure of DKDP (1=0.96) under the acti on of ul tt•aweak thermal neutron f Inx (fig -P, curve I , P) .
In the case of T)KDP ( g) in the cosmic background condi tions a weak posi tive neutron emission is observed (
But at TX/ T = 100 the sign of AN is changed, that ts indicate
appearance of attenua tion of external ther•mal neutron i effect. The change in TSD spectrum at TX/ T > 100 in contr•ast to cosmic background condi t inns is corresponding to suppress toti o t?
| spontaneous de formations in partial y deutera ted DKDP
3. Di scussi on The balance of ampl i ficati on—attenuation processes crystal near Tc upon the passing through it of external neutron flux is deutermi nine by: a) the process of i nelastic, scattering of thermal on lattice deuterons , that is lead to ” posj ti vat’ emissi on > (in reference to background flux) ; |
e. rys ta I s
in DKDP thermal neutrons neu tron |
h) the process of capture of background thermal neutrons by tha (DTI] complex located in crystal , by the “nega ti
neutron emission <N >
Taki to ae.ecun-t a •or•evi ous work data 3] i t can be that
(1)
where P bac kground thermal neutron
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ICCF-6 October 13-18, 1996 Japan
scattering on lattice DKDP deu teron; P is probabili ty of
n deuteron—donor splitting by coherent multi phonon excitation (GMP,) with taking to account neutron diffusion depending on i x/ T or
probability of dd—reaction initiation by the neutron Mossbauer• effect [4, 5].
neutron yield (n/cm *s) in thermonuc lear old—reaction, to be occur on the spheres surrounding C.ME (on the isoenergetic surface e-22.5 kev
The captured in DKDP crys tal part of neutron flux <N can be obtained by the next way:
(2)
c where P ( DH) — is a probability of thermal neutron capture by
r DHI compl exes with •taking to account thermal neutron diffusion, which depends upon the I / TF is a thermal neu tron -r i ux x passing through the crystal ; V is a volume of crystal.
c
Therefore the total expression for balance of neutron effects in DKDP crystal. near depending on relative value or thermal neutron background ( i / i ) ; substi tution index (x) and crys tai mass (m=V p) wili assume the form:
This semiempiric•.al equation is valid only for crys ta I
| th mass more than some cryt•i caj vaiue | : |
3/4
(4) crit
1/2
where ( Nx/ N ) i s a minimum number ot therma i neutrons
( passing through the crystal for ferroelectric phase trans i ti or’ time) that can ini tiate t’ effect,” N (3) more than standard djvi at. ion (J higher then background ; a current
indi cation of detector which corresponds to flux T rnax maximum indication of detec tor in used geometry of experi merit.. Semi empirical equation ( 3), with “taking to account condition (4) makes it possible to compute theoreti cal dependences of’ N (T / T )
(x) and N (m), which are in a good agreement wi th experimental
nata obtained, make possible to conclude that. to observe neutron effects -in deute-r•ated non—equi I i crystals
it is nacessecy, in each case, t.o optimize crystal pat-amet.ec•s and externai thermal neutron background At m>mcri t as well as corresponding values TX/i and x wi th taki ng ae.e.oun e. rys i
structure tion, i t, possi to tain reproduci resul ts, that, in fact, are a value of balance be ampl i r i.cation and a t tenua tion or external ( background )
References
- Lipson , .gakov D.M. . Sauni.n P,.l. // Lett- 62 (10) 828
( 199b) _ fiakov 1). M. , Saunitm F,.l. // J.Tech.P11Yß.t,eLt;,
Gaunt n F,- , Kuznet.sc,v V. A – // Phys. 1996 ( to be pub t i shed).
- Kozima H // Nuovo (i imatlt;o A?’i’ , ( 1994).
- stein P. // Trans Fusion tl’ee.h. P6T , 461 (
Capti ons to ti gores
Pig. 1 . manta t arrangement I — Polyethlene (Co) , de Lee. top; ‘3 counters; 4 si e.orte oi l ; 259 Cd foi ; 6 cryostat, wi I)KDP (‘PSI) cell ) , – neutron source
Fig. BFee.t.ra and tteut.t•on emi ,qsi on i ntensi ty for DKDP crystals cooling ( heating) the vie,.init.y of T : curves t — TGI) spectra for N ‘N —100 e.ortdi ti on; curves 2 (dashed line) spee.tr•a for cosmic neut.r•on background conditions (NK/No=I ) ;
neu tron emi i on i nt,ensi with subtraction of tai ned out, and ) .
‘PSI) spec. tara and t.r•orj emi s-3Bion intensi ty
( x—c). 80) crystals upon e,ooline iti vicini ty of : curve I spec, trum rot’ e.oe,mie. bae.kgt•ound condi tinn (Nx/N —I) curve 2
emission i titernqity wt th subtrae,tion of background.
Fig. 3b. Just; the same as a, but tor Nx/N —100 ( IPST)
peak is t; ted on 4K -i n t,he Pie i d I ower temperatures (curve I); AN was negative sign (curve P).
Fig – 4. Neutron yield v€-wsUs crystal mass at; cosmic thermal neutron background ( N x/N — 1) (‘or c.v•ys s 96; O -80;
- 60) upon the tr•atiS t, i ti e.a[ e.ut•ves deri ved
f com equat.i ons , (4) ( Poi wi th standard devi ati ons are obtai ned from ment)
Pi E. b- Neu y i e i d versus e.r•ystal mass; for DKDP 96 and K—O.80) upon the i ti through at thermal neutron
Nx/ N Theot•eti cal e.utwv•es derived from ( 3) , (4)
(Points wi tti dev-iat’i are obtained from
Fig. 6. Neutron y i el d ver•sup, back-ground condi ti ons (Nx/N ) for g) et•yst.al upon the transi t, ion througlt Tc-
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ICCF.6 October 13-1b 19% Japan
Pig. 7. Neutron yi eld versus D—H substitition index (x) in e„osrnic background conditions (N / N —100, g)