Abstract
Full Text
Physics
N. M. Anton’eva, Corresponding Member of the Academy of Sciences of the USSR B. S. Dzhelepov, G. S. Katykhin, V. B. Smirnov
Study of the Decay of $\mathrm{Rh}^{100}$
The radiation of the isotope $\mathrm{Rh}^{100}$ was investigated by means of a magnetic spectrometer of the “Kätron” type with scintillation registration of electrons ($\Delta H\rho/H\rho = 0.5\%$) and scintillation $\gamma$-spectrometers: a single spectrometer, a coincidence spectrometer ($2\tau = 5 \cdot 10^{-8}$ sec), and a total-absorption spectrometer with a NaI crystal with a well.
The isotope $\mathrm{Rh}^{100}$ was obtained either by the reaction $\mathrm{Ag} + \mathrm{p}$ (660 MeV), or as the daughter product of the decay of $\mathrm{Pd}^{100}$ ($^{1}$).
According to ($^{1,2}$), the following decay chain occurs:
\[ \mathrm{Pd}^{100} \xrightarrow[\,]{3.7\ \text{days}} \mathrm{Rh}^{100} \xrightarrow[\,]{20.8\ \text{hours}} \mathrm{Ru}^{100}. \]
Thus, by chemically separating the Rh fraction on fluoroplastic-4, we obtained $\mathrm{Rh}^{100}$ either mixed with other Rh isotopes, or $\mathrm{Rh}^{100}$ in equilibrium with $\mathrm{Pd}^{100}$, or (by separating Rh from Pd 3–4 days after irradiation of the target) pure $\mathrm{Rh}^{100}$.
Identification of the observed $\gamma$ transitions was carried out by observing the growth and decay of the intensities of the $\gamma$ lines and of some conversion lines in the Pd and Rh fractions.
Analysis of the corresponding curves obtained for the Pd fraction (the Pd fraction was separated $\sim 5$ days after irradiation of the target) gave, respectively, the values $T_{1/2} \simeq 20$ hours and 3.7 days. The intensity of these same $\gamma$ lines in the Rh fraction decayed with $T_{1/2} \simeq 20$ hours. From these data it follows that the corresponding $\gamma$ transitions belong to the decay of $\mathrm{Rh}^{100}$. In addition, for a number of $\gamma$ transitions the values $K-L$ were determined, proving their assignment to the decay of the Rh isotope.
For the half-life of $\mathrm{Rh}^{100}$, from the study of the conversion-electron spectrum we obtained the value $18 \pm 1$ hours (in ($^{1}$) the value $T_{1/2} = 20.8$ hours is apparently overestimated because of the presence of an admixture of $\mathrm{Pd}^{100}$).
Investigation of the conversion-electron spectrum of $\mathrm{Rh}^{100}$ revealed the presence of a number of groups of closely spaced lines; the energies of the corresponding $\gamma$ transitions, the values $K-L$, $K/L$, and the relative intensities of the conversion electrons are given in Table 1.
Before the present work, the conversion-electron spectrum of $\mathrm{Rh}^{100}$ had been investigated only in ($^{1}$), with an instrumental resolution of $\simeq 3.5\%$; the authors detected about 10 $\gamma$ transitions. In the present work about 60 new $\gamma$ transitions belonging to the decay of $\mathrm{Rh}^{100}$ were discovered. In studying the $\gamma$ spectra of $\mathrm{Rh}^{100}$, such complexity of the spectrum must be taken into account. The results of work ($^{3}$) on the $\gamma$ radiation of $\mathrm{Rh}^{100}$ can be considered only with respect to entire groups of lines which the authors of ($^{3}$) took to be single lines.
In the present work, in studying the $\gamma$–$\gamma$ coincidence spectra of $\mathrm{Rh}^{100}$, small energy regions of the $\gamma$ spectrum, $\sim 20$–40 keV, were fixed, and their coincidence with the rest of the $\gamma$ spectrum was studied. In this way the energy range from 200 to 2500 keV was analyzed in detail. The results obtained are presented in Table 2. They are in good agreement with the data of the conversion spectrum and confirm the complex structure of individual groups of lines. Thus, for example, from the results obtained from the $\gamma$–$\gamma$ coincidence spectrum it follows that there are at least 3 components of the 1360-keV group, 2 of which are in cascade, while the 3rd coincides with neither of the first two.
To the article by N. M. Anton’eva, B. S. Dzhelepov, G. S. Katykhin, and V. B. Smirnov
Visible labels in the decay scheme:
- \(543\)
- \(E2\)
- \(538\,(E2)\)
- \(1082\)
- \(234\)
- \(287\)
- \(826\)
- \([[unclear: gamma-ray energy]]\)
- \(329\)
- \(908\)
- \(1347\)
- \(1800\)
- \(742\)
- \(855\)
- \(1030\)
- \(1570\)
- \(2170\)
- \(368\)
- \(581\)
- \(112\)
- \(1205\)
- \(1490\)
- \(1930\)
- \(2480\)
- \(428\)
- \(658\)
- \(1180\)
- \(1270\)
- \(584\)
- \(803\)
- \(1420\)
- \(1620\)
- \(2700\)
- \(302\)
- \(670\)
- \(890\)
- \(1417\)
- \(2240\)
- \(2780\)
- \(451\)
- \(818\)
- \(1040\)
- \(1560\)
- \(1652\)
- \(2385\)
- \(2930\)
- \(438\)
- \(512\)
- \(877\)
- \(1098\)
- \(1620\)
- \(340\)
- \(427\)
- \(574\)
- \(837\)
- \(1006\)
- \(1225\)
- \(1750\)
- \(3100\)
- \(297\)
- \(445\)
- \(530\)
- \(660\)
- \(747\)
- \(1333\)
- \(3230\)
- \(387\)
- \(534\)
- \(619\)
- \(837\)
- \(1205\)
- \(1420\)
- \(3330\)
- \(438\)
- \(500\)
- \(649\)
- \(877\)
- \(947\)
- \(1318\)
- \(1540\)
- \(3430\)
Nuclide label visible at left:
\[ {}^{100}_{44}\mathrm{Ru}_{56} \]
Beta-transition labels visible at bottom:
\[ \beta^{+}\ 2680 \]
\[ 2120,\quad 1600,\quad 1300,\quad 800,\quad 380,\quad 200 \]
Right-side label:
\[ \beta^{+} \]
Half-life label:
\[ 18 \pm 1\ \text{h} \]
Table 1
Energies of γ transitions; values of \(K-L\), \(K/L\); relative intensities of conversion electrons; energies of sum transitions of \(\mathrm{Rh}^{100}\)
| No. | Energy of conversion electrons \(E_e\), keV | Interpretation | \(K-L\), keV \((K/L)\) | Relative intensity of conversion electrons | \(h\nu\), keV, conversion | \(h\nu\), keV, γ spectrum | Energy of sum γ transitions, keV | \(h\nu\), keV, \(^{(1)}\) | Rel. intensity of conversion electrons \(^{(1)}\) |
|---|---|---|---|---|---|---|---|---|---|
| 1 | \(265\pm2\) | \(K\) | — | — | \(287\pm2\) | — | — | — | — |
| 2 | \(275\pm2\) | \(K\) | — | \(4\pm1\) | \(297\pm2\) | — | — | — | — |
| 3 | \(280\pm2\) | \(K\) | — | \(2.0\pm0.6\) | \(302\pm2\) | 300 | — | 301.2 | 5.3 |
| 4 | \(294\pm2\) | \(L\,297\) | — | \(1.6\pm0.4\) | — | — | — | — | — |
| 5 | \(318\pm2\) | \(K\) | — | 0.6 | \(340\pm2\) | — | — | — | — |
| 6 | \(346\pm2\) | \(K\) | — | \(1\pm0.3\) | \(368\pm2\) | 365 | — | 370 | 0.9 |
| 7 | \(405\pm2\) | \(K\) | — | \(2.5\pm0.5\) | \(427\pm2\) | — | — | — | — |
| 8 | \(416\pm2\) | \(K\) | — | \(5\pm1\) | \(438\pm2\) | 440 | — | — | — |
| 9 | \(423\pm2\) | \(K\) | \(19.5\pm1\ (5.0)\) | \(7\pm1\) | \(445\pm2\) | — | — | 442.4 | 21.3 |
| 10 | \(429\pm2\) | \(K\) | \(19.2\pm1\ (6.0)\) | \(18\pm2\) | \(451\pm2\) | — | — | — | — |
| 11 | \(442\pm3\) | \(L\,445\) | — | \(1.5\pm0.3\) | — | — | — | — | — |
| 12 | \(448\pm1\) | \(L\,451\) | — | \(3.0\pm1\) | — | — | — | — | — |
| 13 | \(478\pm2\) | \(K\) | — | \(2\pm0.4\) | \(500\pm2\) | — | — | — | — |
| 14 | \(490\pm2\) | \(K\) | — | \(0.7\pm0.3\) | \(512\pm2\) | — | — | — | — |
| 15 | \(498\pm2\) | \(K\) | — | \(4\pm1\) | \(520\pm2\) | — | — | — | — |
| 16 | \(502\pm2?\) | \(K\) | — | \(3.5\pm1\) | \(524\pm2\) | — | — | — | — |
| 17 | \(508\pm3\) | \(K\) | — | \(5\pm1\) | \(530\pm3\) | — | — | — | — |
| 18 | \(512\pm2\) | \(K\) | — | \(9\pm2\) | \(534\pm2\) | — | — | — | — |
| 19 | \(516\pm2\) | \(K\) | \(19\pm0.7\ (6.0)\) | \(35\pm5\) | \(538\pm2\) | 540 complex | 540 | 535.3 | 100 |
| 20 | \(521\pm2\) | \(K\) | \(19\pm0.7\ (6.0)\) | \(100\pm5\) | \(543\pm2\) | — | — | — | — |
| 21 | \(535\pm2\) | \(L\,538\) | — | \(6\pm1\) | — | — | — | — | — |
| 22 | \(540\pm2\) | \(L\,543\) | — | \(15\pm2\) | — | — | — | — | — |
| 23 | \(562\pm3\) | \(K\) | \(18.5\pm1\ (3.0)\) | \(2.5\pm0.3\) | \(584\pm3\) | 600 | — | — | — |
| 24 | \(569\pm2\) | \(K\) | \(19\pm1\ (3.0)\) | \(4.0\pm0.5\) | \(591\pm2\) | — | — | — | — |
| 25 | \(578\pm2\) | \(L\,584\) | — | \(1.0\pm0.3\) | — | — | — | — | — |
| 26 | \(588\pm1\) | \(L\,591\) | — | \(1.5\pm0.3\) | — | — | — | — | — |
| 27 | \(597\pm2\) | \(K\) | — | \(1.7\pm0.3\) | \(619\pm2\) | — | — | — | — |
| 28 | \(617\pm2\) | \(K\) | — | \(1.5\pm0.3\) | \(639\pm2\) | — | — | — | — |
| 29 | \(627\pm2\) | \(K\) | — | \(1.6\pm0.3\) | \(649\pm2\) | 650 | — | — | — |
| 30 | \(636\pm2\) | \(K\) | — | \(1.6\pm0.3\) | \(658\pm2\) | — | — | — | — |
| 31 | \(648\pm3\) | \(K\) | — | \(0.9\pm0.2\) | \(670\pm3\) | — | — | — | — |
| 32 | \(658\pm3\) | \(K\) | — | \(1.6\pm0.3\) | \(680\pm3\) | — | — | — | — |
| 33 | \(712\pm2\) | \(K\) | — | \(1.0\pm0.2\) | \(734\pm2\) | 740 | — | — | — |
| 34 | \(720\pm3\) | \(K\) | — | \(0.6\pm0.2\) | \(742\pm3\) | — | — | 742.4 | 0.6 |
| 35 | \(725\pm3\) | \(K\) | — | \(0.5\pm0.2\) | \(747\pm3\) | — | — | — | — |
| 36 | \(781\pm3\) | \(K\) | — | \(0.4\pm0.1\) | \(803\pm3\) | — | — | — | — |
| 37 | \(786\pm3\) | \(K\) | — | \(0.8\pm0.2\) | \(808\pm3\) | — | — | — | — |
| 38 | \(797\pm3\) | \(K\) | — | \(3.0\pm0.4\) | \(818\pm3\) | 820 complex | — | — | — |
| 39 | \(804\pm2\) | \(K\) | \(20\pm2\) | \(9\pm1\) | \(826\pm2\) | — | — | 822.5 | 9.7 |
| 40 | \(814\pm4\) | \(K\) | — | \(3.5\pm0.6\) | \(835\pm4\) | — | — | — | — |
| 41 | \(824\pm2\) | \(L\,826\) | — | — | — | — | — | — | — |
| 42 | \(853\pm3\) | \(K\) | — | \(0.9\pm0.2\) | \(877\pm3\) | — | — | — | — |
| 43 | \(867\pm1\) | \(K\) | — | \(1.1\pm0.3\) | \(890\pm3\) | — | — | — | — |
| 44 | \(907\pm3?\) | \(K\) | — | \(0.7\pm0.2\) | \(929\pm3\) | — | — | — | — |
| 45 | \(925\pm3\) | \(K\) | — | \(0.7\pm0.2\) | \(947\pm3\) | — | — | — | — |
| 46 | \(984\pm4\) | \(K\) | — | \(0.6\pm0.2\) | \(1006\pm4\) | 1040 | — | — | — |
| 47 | \(1020\pm4\) double | \(K',K\) | — | \(0.6\pm0.2\) | \(1040\pm4\) | — | — | — | — |
| 48 | \(1060\pm4\) | \(K\) | — | \(0.7\pm0.2\) | \(1082\pm4\) | — | 1080 | — | — |
| 49 | \(1076\pm3\) | \(K\) | — | \(0.9\pm0.2\) | \(1098\pm3\) | — | — | — | — |
| 50 | \(1090\pm3\) | \(K\) | — | \(1.5\pm0.2\) | \(1112\pm3\) | 1120 | — | 1108 | 1.5 |
| 51 | \(1109\pm3\) | \(L\,1112\) | — | \(0.4\pm0.1\) | — | — | — | — | — |
| 52 | \(1183\pm3\) | \(K\) | — | \(0.5\pm0.1\) | \(1205\pm3\) | — | — | — | — |
| 53 | \(1203\pm4\) | \(K\) | — | \(0.7\pm0.2\) | \(1225\pm5\) | — | — | — | — |
| 54 | \(1296\pm3\) | \(K\) | — | \(0.3\pm0.1\) | \(1318\pm3\) | — | — | — | — |
| 55 | \(1314\pm4\) | \(K\) | — | \(0.6\pm0.2\) | \(1335\pm4\) | 1360 complex | 1360 | 1358.2 | 2.8 |
| 56 | \(1325\pm4\) | \(K\) | — | \(1.3\pm0.2\) | \(1347\pm4\) | — | — | — | — |
| 57 | \(1347\pm4\) | \(K\) | — | \(3.0\pm0.5\) | \(1369\pm4\) | — | — | — | — |
| 58 | \(1344\pm4\) | \(L\,1347\) | \(20\pm2\) | — | — | — | — | — | — |
| 59 | \(1366\pm3\) | \(L\,1369\) | \(19.7\pm1\) | — | — | — | — | — | — |
| 60 | \(1380\pm5\) | \(K\) | — | \(0.5\pm0.2\) | \(1400\pm5\) | — | — | — | — |
| 61 | \(1395\pm5\) | \(K\) | — | \(0.2\pm0.1\) | \(1417\pm5\) | — | — | — | — |
| 62 | \(1409\pm5\) | \(K\) | — | \(0.3\pm0.1\) | \(1420\pm5\) | — | — | — | — |
| 63 | \(1519\pm5\) | \(K\) | — | \(0.3\pm0.1\) | \(1540\pm5\) | \(1560\pm20\) complex | — | — | — |
| 64 | \(1540\pm5\) | \(K\) | \(20\pm2\ (4.0)\) | \(0.8\pm0.2\) | \(1560\pm5\) | — | — | 1557.4 | 1.7 |
| 65 | \(1548\pm4\) | \(K\) | \(19.5\pm2\ (4.0)\) | \(1.2\pm0.2\) | \(1570\pm4\) | — | — | — | — |
| 66 | \(1558\pm4\) | \(L\,1560\) | — | \(0.2\pm0.1\) | — | — | — | — | — |
| 67 | \(1568\pm3\) | \(L\,1570\) | — | \(0.3\pm0.1\) | — | — | — | — | — |
| 68 | \(1597\pm5\) | \(K\) | — | \(0.4\pm0.1\) | \(1620\pm5\) | \(1620\pm20\) | — | — | — |
| 69 | \(1630\pm5\) | \(K\) | — | \(0.4\pm0.2\) | \(1652\pm5\) | — | — | — | — |
| 70 | \(1728\pm7\) | \(K\) | — | 0.2 | \(1750\pm7\) | 1890 complex | 1890 | — | — |
| 71 | — | — | — | — | — | 1930 complex | — | 1934.1 | 0.1 |
| 72 | — | — | — | — | — | 2110 | 2110 | — | — |
| 73 | — | — | — | — | — | \(2380\pm30\) | — | 2379 | 1.0 |
| 74 | \(2363\pm7\) | \(K\) | — | — | \(2385\pm7\) | \(2480\pm50\) | 2480 | — | — |
| 75 | — | — | — | — | — | \(2700\pm30\) | 2700 | — | — |
| 76 | — | — | — | — | — | \(2780\pm30\) | 2780 | — | — |
| 77 | — | — | — | — | — | \(2930\pm30\) | \(\sim2930\) complex | — | — |
| 78 | — | — | — | — | — | \(3100\pm50\) | \(3100\pm\) | — | — |
| 79 | — | — | — | — | — | \(3250\pm50\) | \(3220\pm\) | — | — |
| 80 | — | — | — | — | — | \(3330\pm60\) | \(3300\pm\) | — | — |
| 81 | — | — | — | — | — | \(3430\pm60\) | \(3400\pm\) | — | — |
| 82 | — | — | — | — | — | — | — | — | — |
In the spectrum of conversion electrons, 4 lines with close energies were indeed found (see Tables 1 and 2). All these facts are reflected in the proposed decay scheme of \(\mathrm{Rh}^{100}\) (see Fig. 1).
The hard \(\gamma\)-radiation of \(\mathrm{Rh}^{100}\) was studied with Pb filters (\(l=5\) cm). Ten new lines were found, apparently corresponding to direct \(\gamma\)-transitions from excited states to the ground state.
Table 2
Results of the study of the \(\gamma\)—\(\gamma\)-coincidence spectra of \(\mathrm{Rh}^{100}\)
| Fixed \(\gamma\)-transition, \(h\nu\), keV | \(\gamma\)-transitions coincident with the data \(*\), \(h\nu\), keV |
|---|---|
| 540 | 2380, 2100, 1930, 1560, 1360 left, 1110, 1040, 820, 540, 440, 300. No \(\gamma\)—\(\gamma\) with 1360 right. |
| 820 right | 1560, 1110, 820 left, 540 right, 440, 300. No \(\gamma\)—\(\gamma\) with 1900 and above |
| 820 left | 2100, 1560, 1360, 820 right, 540, 300. No \(\gamma\)—\(\gamma\) (440) and above 2100 |
| 1040 | 1360 left, 1110, 820 left, 540, 440. No \(\gamma\)—\(\gamma\) with 1560 and above |
| 1110 | 1360 right, 1040, 820 right, 540, 440, 300. No \(\gamma\)—\(\gamma\) with 1560 |
| 1360 right | 1560, 1110, 820 left, 540, 440, 300. No \(\gamma\)—\(\gamma\) with 1360 left and above 1560 |
| 1360 left | 1360 left, 1040, 820, 540, 440, 300. No \(\gamma\)—\(\gamma\) with 1560, 1360 right |
| 1560 | 1360, 820, 540, 440, 300. No \(\gamma\)—\(\gamma\) 1560, 1110, 1040 |
| 2100 | 1000, 820 left, 600, 540 left, 440, 300 |
| 2380 | 540, 300 |
* The designations right and left for complex \(\gamma\)-lines in coincident \(\gamma\)-transitions are not given in those cases when coincidences with several components of the \(\gamma\)-line are observed.
To obtain information on the energies of the levels of \(\mathrm{Ru}^{100}\), the \(\mathrm{Rh}^{100}\) source was placed in the well of an NaJ crystal and outside it; the rise and fall of the intensity of the “sum lines” were observed, and their assignment to \(\mathrm{Rh}^{100}\) was shown.
The energies of the sum \(\gamma\)-transitions are given in Table 1.
From the data we obtained on the \(\beta^{+}\)-spectrum of \(\mathrm{Rh}^{100}\), one may assume the existence of two new components of the \(\beta^{+}\)-spectrum. In Fig. 1 they are shown by dashed lines.
On the basis of the totality of the results obtained, the decay scheme of \(\mathrm{Rh}^{100}\) shown in Fig. 1 is proposed.
Leningrad State University
named after A. A. Zhdanov
Received
26 IX 1964
CITED LITERATURE
- L. Marquez, Phys. Rev., 92, 1511 (1953).
- N. M. Anton’eva, B. S. Dzhelepov, G. S. Katykhin, V. B. Smirnov; Abstracts of Reports at the XIV Annual Conference on Nuclear Spectroscopy, Tbilisi, 1964.
- B. Basu, A. P. Patro, Nuclear Phys. 29, 672 (1962).