Nuclear Data Section
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Memo CP-D/696

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12 May 2011
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N. Otsuka

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Thick target yield given in decay rate per charge (PRELIM.A070)
Memo CP-D/631

In preliminary transmission PRELIM.A070, the following entries give thick target
yields in dps/μA-h (DPS/MUAHR):
A0122, A0199, A0226, A0256, A0257, A0259, A0260, A0269, A0294(P.P. Dmitriev, N.N. Krasnov et al. from Obninsk)
A0211, A0212, A0331(G.Vakilova, S. Mukhammedov et al. from Tashkent)First of all, I appreciate systematic addition of English translation information toREFERENCE of these entries, which helped my analysis a lot.

Among three yields currently defined in EXFOR, (1) “physical thick target yield”(,TTY,,PHY), (2) “production thick target yield” (,TTY,,DT) and (3) “saturated thicktarget yield” (,TTY) - , only the physical thick target yield can take dps/ μA-h (c.f. Eqs
2, 4 and 8 of Memo CP-D/631).
Quantity
Physical thick target yield
Production thick target yield
Saturation thick target yield

Quantity code

Unit family,TTY,,PHY,TTY,,DT,TTY

TTT
TTY
TTY

Unit (Example)
dps/μA-h, MBq/Coul.
MBq/ μA
MBq/ μA

In PRELIM.A070, the quantity codes of above entries are changed from ,TTY
to ,TTY,,PHY as expected from above the table. However I learned that the “yield”
given in dps/μA-h (or MBq/ μA-h, MBq/Coulomb etc. belongs the unit family TTT) is
not always the physical thick target yield:
If we obtain the production thick target yield A t after irradiation time t, thecorresponding physical thick target yield y is
y = A(t )λ1 − e − λt. If irradiation time is enough shorter than the life-time of the product nuclide (λt <<1), y~ A(t)/t (i.e. physical thick target gives the slope of A(t) at t=0), and we cansimply convert the production thick target yield to the physical thick target yield
without correction due to decay during irradiation. But Sandor Takacs explained methat this approximation has been wrongly sometimes applied even for short half-lifeproducts.
In the A0211 article [1], their “yield” is defined by above the equation, and we may
use TTY,,PHY in PRELIM.A070. For other entries in PRELIM.A070, however, weshould probably use another code when the definition of the “yield” is not clear fromthe article.
For EXFOR A0168 (not included in PRELIM.A060), yields in MBq/ μA-h are codedwith ,TTY,,DT. In the original article [2], authors introduced the “physical thicktarget” with the equation and ,TTY,,PHY is more suitable than ,TTY,,DT.
In conclusion, I propose compilers to use ,TTY,,(PHY) instead of ,TTY,,PHY whendata are given in dps/μA-h (or other unit codes belonging to the unit family TTT) but
the definition of the quantity is not clear from the article. CAJaD may select more
appropriate code for each entry. Probably sometimes decision may depend on eachcompiler as we have been experienced for decision of isomeric transition contribution
M+ and (M).
Addition of the following new code to dictionaries should be considered if CAJaD
applies ,TTY,,(PHY) to some entries in the final TRANS.A070.
Dictionary 34 (Modifiers)(PHY)
Uncertain if yield is for infinitesimal irradiation
Dictionary 236 (Quantities),TTY,,(PHY) Thick/thin target yield (activity) per induced charge(Compilers uncertain if yield is for infinitesimal irradiation)
In old dictionary (e.g., TRANS.9073 April 1997), we can see the unit family field isblank for DPS/MUAHR in dictionary 24. I think people could not find a good solution atthat time.
I thank Sandor Takcs for his useful comments on this issue.
Reference[1] G. Vakilova et al., Sov. Atom. Energy 55(1983)598 (EXFOR A0211)[2] P.P. Dmitriev and G.A. Molin, INDC(CCP)-188 (1982) (EXFOR A0168)

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