Weisskopf Units Research Articles

The character of high-spin positive parity states in41Ca

The use of the 38Ar( alpha ,n gamma )41Ca reaction has enabled rigorous spin assignments to be made for five high-spin states: 3369 keV (Jpi =11/2+); 3830 (15/2+); 3914 (13/2+); 3976 (11/2+) and 4519 (13/2+). An E3 transition strength of 24 (+5,-3) Weisskopf units for the 3369 to 0 keV transition encourages a description of the positive parity states by the weak coupling of a 1f7/2 neutron to the 3- and 5- vibrations in 40Ca.

Angular correlation and decay mode measurements inCa41using theCa42(He3, αγ)Ca41reaction

$\ensuremath{\gamma}$-ray angular correlations have been measured for the 2.010, 2.960, 3.200, 3.526, 3.740, and 4.090 MeV states in $^{41}\mathrm{Ca}$ using the $^{42}\mathrm{Ca}(^{3}\mathrm{He}, \ensuremath{\alpha}\ensuremath{\gamma}))^{41}\mathrm{Ca}$ reaction. An $E3$ strength of (${1.5}_{\ensuremath{-}0.7}^{+0.9}$) Weisskopf units has been determined for the 2.010\ensuremath{\rightarrow}0 MeV transition from the measured mixing ratio, $\ensuremath{\delta}=\ensuremath{-}0.095\ifmmode\pm\else\textpm\fi{}0.022$, and a previous lifetime measurement. The decay scheme and angular correlations imply a spin assignment of ${J}^{\ensuremath{\pi}}={\frac{3}{2}}^{+}$ for the 3.526 MeV state and strongly suggest that ${J}^{\ensuremath{\pi}}={\frac{3}{2}}^{+}$ for the 3.740 MeV state and ${J}^{\ensuremath{\pi}}={\frac{5}{2}}^{+}$ for the 4.090 MeV state. Decay schemes have been measured for four $T=\frac{3}{2}$ states in $^{41}\mathrm{Ca}$ at 5.814, 6.820, 7.146, and 8.54 MeV. Analog to antianalog state transitions have been observed from the 5.814, 6.820, and 7.146 MeV levels. Such a transition was not reported in a previous study of the decay of the 5.814 MeV state. The 8.54 MeV state decays primarily by neutron emission but has a 1 to 3% $\ensuremath{\gamma}$-decay branch. In addition, the $^{41}\mathrm{K}(^{3}\mathrm{He}, t)^{41}\mathrm{Ca}$ reaction was used to verify the $T=\frac{3}{2}$ assignment for the 5.814 MeV state and the $^{40}\mathrm{Ca}(d, p\ensuremath{\gamma})^{41}\mathrm{Ca}$ reaction was used in the study of the 3.731-3.740 MeV doublet.NUCLEAR REACTIONS $^{42}\mathrm{Ca}(^{3}\mathrm{He}, \ensuremath{\alpha})$, $E=18$ MeV; $^{41}\mathrm{K}(^{3}\mathrm{He}, t)$, $E=18$ MeV; $^{40}\mathrm{Ca}(d, p)$, $E=11$ MeV; measured coinc. $\ensuremath{\gamma}$ spectrum, ${I}_{\ensuremath{\gamma}}(\ensuremath{\theta}\ensuremath{\gamma})$. $^{41}\mathrm{Ca}$ deduced $\ensuremath{\delta}$, $B(\ensuremath{\Lambda})$, $J$, branching ratios.

Further evidence of rotational structure in26Mg

The 4.350 MeV(3+) and 5.716 MeV(4+) states in 26Mg have been studied with particle gamma ray angular correlation measurements using the reactions 26Mg( alpha alpha ' gamma ) 26Mg with Ge(Li) detectors. Branching ratios and E2/M1 mixing ratios were deduced; in particular a new 815 keV transition (5.716 to 4.901 MeV) has been found. The E2 transition strengths of the cascading gamma rays with 1366 keV (4+ to 3+) and 1412 keV (3+ to 2+) of 3+or-1 and 9-3+4 Weisskopf units respectively support the assignment of the 4.350 and 5.716 MeV states to the Kpi =2+ rotational band based on the 2.938 MeV (2+) states. The results are compared with recent deformed shell model calculations. Nineteen further states between 6 and 9.1 MeV were excited; a decay scheme has been established and several branching ratios are reported. The possible assignment of high spins to some of the higher states is discussed.

Rotational states in26Mg

The decay properties of the levels at 3.941(3+), 5.476(4+) and 5.716 MeV (4+) in 26Mg have been investigated. Particle gamma-ray angular correlations were measured following the reactions 26Mg( alpha , alpha ' gamma )26Mg and 26Mg(p,p' gamma )26Mg enabling accurate branching ratios and E2/M1 mixing ratios to be determined. The lifetimes were obtained with the reaction 23Na( alpha ,p gamma )26Mg using the Doppler shift attenuation method. The transition from the 5.476(4+) to the 3.941 MeV (3+) state is shown to have an E2 strength of 12+9-4 Weisskopf units whilst the transitions from the 3.941 MeV state itself are essentially dipole. The data together with the revised branching ratios result in a new assignment of states to the Kpi =2+ and 3+ rotational bands.

High-spin state at 3918 keV inAl26

The level at 3918 keV in $^{26}\mathrm{Al}$ has been populated with the $^{23}\mathrm{Na}{(\ensuremath{\alpha},n)}^{26}$ Al reaction and shown to have a spin of ${7}^{+}$ although a ${5}^{+}$ possibility cannot be completely excluded. The level decays 100% to the ${5}^{+}$ ground state and has an $E2$ strength of 6.7 \ifmmode\pm\else\textpm\fi{} 2.2 Weisskopf units if the ${7}^{+}$ assignment is assumed. Recent calculations with the Glasgow shell model program using the interaction of Preedom and Wildenthal predict a ${7}^{+}$ state at this excitation energy.NUCLEAR REACTIONS $^{23}\mathrm{Na}(\ensuremath{\alpha},n\ensuremath{\gamma})$, $E=8.8$ MeV; measured $\ensuremath{\sigma}({\ensuremath{\theta}}_{\ensuremath{\gamma}})$, $P$. $^{26}\mathrm{Al}$ level deduced $J$, $\ensuremath{\pi}$, $\ensuremath{\delta}$.

Ep=1.118MeV resonance in theAl27(p,γ)Si28reaction

The 12.664-MeV level in $^{28}\mathrm{Si}$ has been populated by resonant proton capture at 1.118 MeV in the $^{27}\mathrm{Al}(p,\ensuremath{\gamma})^{28}\mathrm{Si}$ reaction. $\ensuremath{\gamma}$-ray angular distributions have been measured with a 80-${\mathrm{cm}}^{3}$ Ge(Li) detector. The spin of the 11.432-MeV level is most probably 4 with $T=0$; for the 8.413-MeV level, the assignment ${J}^{\ensuremath{\pi}}={4}^{\ensuremath{-}}$ is in agreement with the present data. Mixing ratios for $\ensuremath{\gamma}$-ray transitions have been extracted from the angular distributions. Lifetime and branching-ratio studies have been made at ${E}_{p}=1.118,1.724, \mathrm{and} 2.876$ MeV. Emphasis was given to measurements on levels at 8.413, 9.702, and 11.577 MeV, as possible candidates for the ${4}^{\ensuremath{-}}$, ${5}^{\ensuremath{-}}$, and ${6}^{\ensuremath{-}}$ states of a ${K}^{\ensuremath{\pi}}={3}^{\ensuremath{-}}$ rotational band based on the 6.879-MeV level. The observed $E2$ transition strengths are not in agreement with the above assumption. A strength of 0.3 Weisskopf units is found for the 12.664\ensuremath{\rightarrow}8.413-MeV $M1$ transition, which is in conformity with a ${J}^{\ensuremath{\pi}}\ensuremath{\rightarrow}{J}^{\ensuremath{\pi}}$, $\ensuremath{\Delta}T=1$ transition in a self-conjugate nucleus; this result may suggest the possibility of another interpretation of these negative-parity states, relied on one-particle - one-hole configurations.[NUCLEAR REACTION $^{27}\mathrm{Al}(p,\ensuremath{\gamma})^{28}\mathrm{Si}$, ${E}_{p}=1.724,2.876$ MeV; measured $\ensuremath{\gamma}$-ray branching ratios, Doppler-shift attenuation. ${E}_{p}=1.118$ MeV; measured resonance strength, $\ensuremath{\gamma}$-ray branching ratios, mixing ratios, Doppler-shift attenuuation; deduced transition strengths. Natural targets, Ge(Li) detectors.]

Cumulative and independent population of individual levels via theNi58(α,pγ)Cu61andNi58(α,2pγ)Ni60compound-nucleus reactions: A correlation between level cross sections and angular momenta

The cross sections for the cumulative and independent population of 21 levels in $^{61}\mathrm{Cu}$ and 7 levels in $^{60}\mathrm{Ni}$ via the $^{58}\mathrm{Ni}(\ensuremath{\alpha},p\ensuremath{\gamma})^{61}\mathrm{Cu}$ and $^{58}\mathrm{Ni}(\ensuremath{\alpha},2p\ensuremath{\gamma})^{60}\mathrm{Ni}$ reactions at 19.67-MeV bombardment energy were carefully measured in $p\ensuremath{\gamma}$-coincidence experiments with the protons detected at 90 and 157\ifmmode^\circ\else\textdegree\fi{} relative to the beam direction. Spectra of the coincident protons leading to each level via $\ensuremath{\gamma}$ cascades as well as energy-integrated cross sections were obtained. The angular distributions for the protons above 3.26 MeV of center-of-mass energy were measured at seven laboratory angles between 25 and 168\ifmmode^\circ\else\textdegree\fi{}. Larger anisotropies for the protons from the ($\ensuremath{\alpha},2p$) reaction were observed relative to the ($\ensuremath{\alpha},p$) reaction. Some of the levels in $^{60}\mathrm{Ni}$ were found to have large anisotropies with the maxima at the backward angles. When the cross sections for the cumulative and the independent population of levels of given angular momentum in $^{61}\mathrm{Cu}$ or $^{60}\mathrm{Ni}$ are plotted as a function of the level energy, they are found to decrease rapidly with level energy. The cross sections for cumulative and independent population increase with angular momentum at least for levels with ${J}^{\ensuremath{\pi}}$ values between ${\mathrm{\textonehalf{}}}^{\ensuremath{-}}$ and ${\frac{11}{2}}^{\ensuremath{-}}$. The variation of the level cross sections with level energy follows closely the predictions of the compound statistical model for both the ($\ensuremath{\alpha},p\ensuremath{\gamma}$) and ($\ensuremath{\alpha},2p\ensuremath{\gamma}$) reactions. The experimental cross-section distributions, cross sections for the formation of individual levels and total cross sections for the ($\ensuremath{\alpha},p$) and ($\ensuremath{\alpha},2p$) reactions are compared with detailed calculations based on the statistical theory for nuclear reactions, in which Fermi-gas-model level densities and shell-model combinatorial level densities are employed. The experimental level cross sections and proton evaporation spectra are very well reproduced with level spacing parameters $a$ of 6.56, 7.63, and 5.8 ${\mathrm{MeV}}^{\ensuremath{-}1}$ for $^{61}\mathrm{Cu}$, $^{61}\mathrm{Zn}$, and $^{58}\mathrm{Ni}$, respectively. By comparison with experimental level cross sections the energy dependence of the spin cutoff parameter ${\ensuremath{\sigma}}^{2}$ and the yrast line were determined for $^{61}\mathrm{Cu}$. The $B(E1)$, $B(M1)$ and $B(E2)$ values for transitions originating at 10 MeV of excitation in $^{61}\mathrm{Cu}$ that reproduce the ($\ensuremath{\alpha},p\ensuremath{\gamma}$) and ($\ensuremath{\alpha},2p\ensuremath{\gamma}$) level cross sections were found to be 0.055, 0.085, and 9.5 Weisskopf units, respectively.

Lifetime of theO1841+state at 3.555-MeV excitation

The recoil distance method was used to measure the lifetime of the ${J}^{\ensuremath{\pi}}={4}^{+}$ second excited state of $^{18}\mathrm{O}$ at 3.555-MeV excitation, which was formed via the $^{16}\mathrm{O}(t,p)^{18}\mathrm{O}^{*}$ reaction at ${E}_{t}=3.1$ MeV. The mean life is found to be $\ensuremath{\tau}=46.2\ifmmode\pm\else\textpm\fi{}3$ psec, which corresponds to an $E2$ strength for the 3.55 (${4}^{+}$\ensuremath{\rightarrow} 1.98 (${2}^{+}$) transition of ${|M(E2)|}^{2}=0.64\ifmmode\pm\else\textpm\fi{}0.05$ Weisskopf units. This result is in good agreement with the predictions of recent theoretical calculations in the weak-coupling model, which identifies the lowest-lying ${2}^{+}$ and ${4}^{+}$ states as predominantly 2p-0h states based on $^{16}\mathrm{O}$. The predictions of this model for mirror states $^{18}\mathrm{O}$-$^{18}\mathrm{Ne}$ are discussed. Additional data were obtained coincidentally for states of $^{18}\mathrm{F}$ formed via the competing $^{16}\mathrm{O}(t,n)^{18}\mathrm{F}^{*}$ reaction. The results, which are in good agreement with previous values, are: 0.937-MeV state, $\ensuremath{\tau}=65.4\ifmmode\pm\else\textpm\fi{}5.3$ psec and for the 1.081-MeV state, $\ensuremath{\tau}=26.1\ifmmode\pm\else\textpm\fi{}2.3$ psec.

An E5 transition in 123Te and E5 transitions in general

We have observed an extremely weak 248 keV, E5 transition in 123Te with a strength of 0.05 Weisskopf units. We have also summarized the available experimental information on all E5 transitions.

Gamma-decay of the lowest T = 2 state of 24Mg

The lowest T = 2 level of 24Mg was observed as a resonance in the γ-ray yield from the 23Na(p, γ) 24Mg reaction at E p = 3905±3 keV. Gamma-ray branching ratios for this J π = 0 +, T = 2 level at 15434±3 keV to the J π = 1 + , T = 1 states at 9967±2 keV and 10711±2 keV were measured to be (83±2) % and (17±2) %, respectively. The branching ratios for the decay of the T = 1 levels were also determined. The resonance strength was found to be ωγ = 1.9±0.5 eV. The M1 transition probabilities deduced are Γ γ (M1) = 0.8±0.3 Weisskopf units (W.u.) for the 15434 → 9967 keV transition and Γ γ (M1) = 0.27±0.09 W.u. for the 15434 → 10711 keV transition. A comparison is made between the Γ γ (M1) values deduced from the present experiment and the values calculated from the data on the analogue β-decay of 24Ne.

Nuclear Lifetimes of the 2815- and 3598-keV Levels ofK39

The recoil-distance-Doppler-shift method has been used to measure the lifetimes of the 2815- and 3598-keV levels of $^{39}\mathrm{K}$. These excited states were populated by the reaction $^{6}\mathrm{Li}(^{35}\mathrm{Cl},d)^{39}\mathrm{K}$ using 68-MeV $^{35}\mathrm{Cl}$ ions. The energies of the $\ensuremath{\gamma}$ rays from these two levels were determined with a 55-${\mathrm{cm}}^{3}$ Ge(Li) detector to be 783(\ifmmode\pm\else\textpm\fi{}1), 2815(\ifmmode\pm\else\textpm\fi{}1), and 3598(\ifmmode\pm\else\textpm\fi{}1) keV. The mean lifetime of the 2815-keV level was measured as 79(\ifmmode\pm\else\textpm\fi{}8) psec, and that of the 3598-keV level as 59(\ifmmode\pm\else\textpm\fi{}4) psec. The corresponding $E3$ strengths of 6.0(\ifmmode\pm\else\textpm\fi{}0.1) and 25.5(\ifmmode\pm\else\textpm\fi{}1.5) Weisskopf units are in very good agreement with the phonon-hole model calculations of Goode and Zambick.

Sum rules and two-particle units in the analysis of two-neutron transfer reactions

The problem of two-particle units and sum rules in two-neutron transfer reactions is discussed. Using (t, p) data on 16O, 40Ca, 48Ca, 118Sn, 204Pb, 206Pb, 207Pb and 208Pb targets and available model wave functions, a universal value of the absolute normalization factor D02 is obtained. Utilizing this value the adequacy of the shell-model subspace used in generating the wave functions is studied. With the aid of conveniently defined two-particle units in terms of D02, enhancement factors are calculated for all transitions analyzed, and a quantitative definition of enhanced cross sections is obtained. The relation between the two-particle units introduced here and the Weisskopf units used in connection with electromagnetic reduced transition probabilities is pointed out.

Some E2 Rates in 21185At126

The half-life of a 3/2- level at 1 116 keV excitation energy in 211At has been measured to be 0.57 ± 0.04 nsec, using the delayed-coincidence technique. From a high-resolution study of parts of the conversion-electron spectrum it is shown that the depopulating transitions have the following multipolarities: 169 keV (E2 + (13 ± 2)% M1), 250 keV (E2) and 442 keV (E2). The reduced E2 transition probabilities are compared with theoretical predictions. The M1 rate corresponds to 1/6 400 Weisskopf units, in accordance with the interpretation of the two involved levels as essentially pure π(h9/23) states.

Mean Lifetime and Magnetic Moment of the 2.95-MeV (6+) State ofFe54

The mean lifetime and $g$ factor of the 2.95-MeV ${6}^{+}$ state of $^{54}\mathrm{Fe}$ were measured to be $\ensuremath{\tau}=1.76\ifmmode\pm\else\textpm\fi{}0.03$ nsec and $|g|=1.37\ifmmode\pm\else\textpm\fi{}0.03$, respectively. These results are in agreement with the shell-model assignment ${({{f}_{\frac{7}{2}}}^{\ensuremath{-}2})}_{\ensuremath{\pi}}$ plus a small amount of configuration mixing which accounts for the quenching of the magnetic moment from the Schmidt limit and the enhanced $E2$ rate $B(E2;{6}^{+}\ensuremath{\rightarrow}{4}^{+})=3.2$ Weisskopf units.

Evidence for aKπ=5+Ground-State Rotational Band inAl26

Measurement of $\ensuremath{\gamma}$-ray distributions from the reaction $^{23}\mathrm{Na}(\ensuremath{\alpha},n\ensuremath{\gamma})^{26}\mathrm{Al}$ confirms spin $J=5$ for the 3404-keV level and gives an unambiguous spin assignment of $J=6$ for the 3508-keV level. Measurement of lifetimes and mixing ratios show that both states have positive parity. The excitation energy and the enhanced $E2$ strength of > 11 Weisskopf units for the ${6}^{+}$ to ${5}^{+}$ ground-state transition identify the level at 3508 keV as the ${6}^{+}$ member of a $K={5}^{+}$ rotational band based on the ground state.

The 5 − resonance in the 16O(α, γ) 20Ne reaction at Eα = 4.65 MeV

A resonance at E α = 4647 keV in the 16O(α, γ) 20Ne reaction has been located and assigned to a 5 − state in 20Ne at 8447 ± 3 KeV. The radiative width of the 5 − to 3 − transition has been measured and found to be 13 ± 3 meV corresponding to a transition strength of 26 ± 6 Weisskopf units. Comparisons are made with rotational and shell model predictions.

8543-keV6+State inSi28and the Ground-State Rotational Band

Evidence for the existence of a ground-state rotational band in the nucleus $^{28}\mathrm{Si}$ has been rounded out by a lifetime measurement of the 8543-keV ${6}^{+}$ level. Using the 2203-keV resonance in the $^{27}\mathrm{Al}(p,\ensuremath{\gamma})^{28}\mathrm{Si}$ reaction, and the Doppler-shift attenuation technique, 18 \ifmmode\pm\else\textpm\fi{} 6 fsec is found for the mean life of the ${6}^{+}$ state. It follows that the strength of the ${6}^{+}$ \ensuremath{\rightarrow} ${4}^{+}$ 3926-keV transition is 9.4 \ifmmode\pm\else\textpm\fi{} 3.0 Weisskopf units (W.u.), in good agreement with theoretical predictions. This measurement removes objections that arose from an earlier result of 2.9 W.u. for the ${6}^{+}$ \ensuremath{\rightarrow} ${4}^{+}$ transition strength.

Elastic and inelastic scattering of 14.1 MeV neutrons from fluorine

The angular distributions and cross sections for elastic and inelastic scattering of 14 MeV neutrons from fluorine have been measured. The observed inelastic group has been assigned mainly to the state at 1.56 MeV. The angular distributions generally agree with the predictions of the optical model and the DWBA. The observed cross section for the inelastic group corresponds to a value of |M| 2 = 7 in Weisskopf units.

Lifetimes in 32S

Lifetimes have been measured for five levels in 32S. The levels were populated by inelastic scattering of protons, and the gamma rays were detected at angles between 0° and 127° using a 40 cm3 Ge(Li) detector mounted inside a split annular NaI(Tl) crystal. The spectrometer was used simultaneously as both an escape-suppressed and a three-crystal pair spectrometer. Decay schemes and lifetimes have been determined using thick targets of PbS, MoS2, and sulfur cooled to 77 °K. Lifetime information was obtained both from analysis of the observed gamma-ray line shapes and from analysis of the Doppler shift attenuation in the different target materials. The two methods of analysis agree within the errors. A weak ground-state transition was observed from the J = 3 level at 5.012 MeV, establishing its parity as negative. Analysis of the line shape observed at 0° and the Doppler shift attenuation gave an average lifetime of 7.5 ± 0.5 × 10−13 s. The observed branching ratio (4 ± 0.4% to the ground state) implies an E3 enhancement of 20 ± 2.4 Weisskopf units (W.u.). A similar analysis gave a lifetime of 4.9 ± 0.9 × 10−13 s for the J = 1 level at 4.699 MeV, which implies that the dipole transition to the ground state is highly retarded. Lifetimes have also been measured for levels at 3.780 MeV [Formula: see text], 4.288 MeV (7.4 ± 0.6 × 10−14 s), and 5410 MeV (1.9 ± 0.2 × 10−13 s); the transition strengths are tabulated and discussed.

Properties ofP30Levels from the ReactionSi29(p, γ)P30. II

A previous investigation of the $\ensuremath{\gamma}$-ray decay schemes of 7 resonances in the reaction ${\mathrm{Si}}^{29}(p, \ensuremath{\gamma}){\mathrm{P}}^{30}$ in the range ${E}_{p}=700\ensuremath{-}1750$ keV has been extended to 24 resonances in the range ${E}_{p}=300\ensuremath{-}1800$ keV. The new decay scheme studies were conducted with a 40-cc Ge(Li) detector. The spins, parities, isobaric spins, lifetimes, and transition multipolarity mixings for many resonances and bound states of ${\mathrm{P}}^{30}$ have been determined from an extensive series of angular-correlation, linear-polarization, and Doppler-shift-attenuation measurements. New resonance information includes the discovery that resonances previously reported at ${E}_{p}=1505, 1748, \mathrm{and} 1772$ keV are each doublets. The latter two have components at 1746 and 1749, and at 1773 and 1775 keV, respectively. The 1505-keV "resonance" was found to be a doublet with a separation of 0.7\ifmmode\pm\else\textpm\fi{}0.1 keV by means of high-resolution elastic-scattering measurements. Unique spin assignments for 15 and parity assignments for 11 resonance levels were obtained. The observed resonance strengths $\frac{(2J+1){\ensuremath{\Gamma}}_{\ensuremath{\gamma}}{\ensuremath{\Gamma}}_{p}}{\ensuremath{\Gamma}}$ vary between 0.077 and 14 eV. Several unusually broad odd-parity resonances were observed which have large reduced widths for $p$-wave and $f$-wave capture. The strong contribution of $1{f}_{\frac{7}{2}}$, $2{p}_{\frac{3}{2}}$, and $2{p}_{\frac{1}{2}}$ orbitals to the configuration of states near ${E}_{x}=7$ MeV in ${\mathrm{P}}^{30}$ is revealed. The influence of isobaric spin on the level structure and $\ensuremath{\gamma}$-ray decay properties is apparent. The ${2}^{\ensuremath{-}}$ resonances at ${E}_{p}=1470 \mathrm{and} 1686$ keV and the ${4}^{\ensuremath{-}}$ doublet at 1505 keV are identified as $T$-admixed pairs. Significant revisions of the decay schemes of the 1.45-, 2.94-, 4.14-, 4.50-, and 4.92-MeV levels have resulted from the 40-cc Ge(Li) spectra. The "4.92-MeV level" is shown to be a doublet with components at 4.921\ifmmode\pm\else\textpm\fi{}0.002 and 4.945\ifmmode\pm\else\textpm\fi{}0.005 MeV. By combining results of the angular-correlation, linear-polarization, and lifetime measurements, the following ${J}^{\ensuremath{\pi}}$ assignments are derived for bound levels: 0.71(${1}^{+}$), 1.45(${2}^{+}$), 1.97(${3}^{+}$), 2.54(${3}^{+}$), 2.72(${2}^{+}$), 2.84(${3}^{+}$), 2.94(${2}^{+}$), 3.02(${1}^{+}$), 4.14(${2}^{\ensuremath{-}}$), 4.18(${2}^{+}$), 4.23(${4}^{\ensuremath{-}}$), 4.43(${2}^{+}$), 4.47(${0}^{+}$), 4.50(${1}^{+}$), 4.62(${3}^{\ensuremath{-}}$), 4.92(${5}^{\ensuremath{-}}$ or ${3}^{\ensuremath{-}}$), and 4.94(1). Previous $T=1$ assignments for the bound levels at ${E}_{x}=0.68, 2.94, 4.18, 4.47, \mathrm{and} 4.50$ MeV are strongly supported by the data. Prominent "analog-to-antianalog" $M1$ transitions similar to those in other $s\ensuremath{-}d$ shell nuclei are observed. An average isospin impurity of 7% for levels below 7 MeV in ${\mathrm{P}}^{30}$ is derived from the set of $E1$ transition rates. On the average, the $E2$ transition rates have strengths slightly less than one Weisskopf unit. However, strong $E2$ enhancement is observed for the 2.94\ensuremath{\rightarrow}0.68, 2.54\ensuremath{\rightarrow}0, and 2.72\ensuremath{\rightarrow}0 transitions which have strengths of 21, 15, and 9 Weisskopf units, respectively. Several of the observed odd-parity resonance and bound levels appear to correspond to $T=1$ and $T=0$ members of a two-nucleon spectrum with major components (${s}_{\frac{1}{2}}{f}_{\frac{7}{2}}$), (${d}_{\frac{3}{2}}{f}_{\frac{7}{2}}$), and (${s}_{\frac{1}{2}}{p}_{\frac{3}{2}}$).