Protactinium-215

Properties and data of the isotope ²¹⁵Pa.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Protactinium-215 is a radioisotope of the chemical element protactinium, which has 124 neutrons in its atomic nucleus in addition to the element-specific 91 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 215. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²¹⁵Pa is exclusively for academic purposes.

In 1979 a report appeared in which the short-lived isotope protactinium-215 was described for the first time. In the underlying experiments, 165–202 MeV argon-40 ions from the UNILAC accelerator struck a tantalum-181 target, producing the nuclide in the fusion-evaporation reaction

¹⁸¹Ta(⁴⁰Ar,6n)²¹⁵Pa [1].

See also: List of individual Protactinium isotopes (and general data sources).

General data

Name of the isotope:Protactinium-215; Pa-215Symbol:²¹⁵Pa or 21591PaMass number A:215 (= number of nucleons)Atomic number Z:91 (= number of protons)Neutrons N:124Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.3626373626374 (= neutron-proton ratio)Neutron excess (N-Z):33Isotopic mass:215.019110(90) u (atomic weight of Protactinium-215)Nuclide mass:214.9691957 u (calculated nuclear mass without electrons)Mass excess:17.80085 MeVMass defect:1.767417496 u (per nucleus)Nuclear binding energy:1646.33879302 MeV (per nucleus)
7.65738973 MeV (average binding energy per nucleon)Separation energy:S_N = 9.727(116) MeV (first neutron)
S_P = 0.179(83) MeV (first proton)Half-life:14(2) msDecay constant λ:49.510512897139 s^-1Specific activity α:1.386787361461 × 10⁺²³ Bq g^-1
3748073949896.8 Ci g^-1Spin and parity:
(nuclear angular momentum)(9/2-)Year of discovery:1979

Radioactive Decay

Half-life T_½ = 14(2) ms respectively 1.4 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²¹¹Ac	100 %	8.236(63) MeV

Parent Nuclides

Direct parent isotope is: ²¹⁹Np.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 124) and isobaric (same nucleon number A = 215) with Protactinium-215. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 124	Isobar A = 215
75	¹⁹⁹Re
76	²⁰⁰Os
77	²⁰¹Ir
78	²⁰²Pt
79	²⁰³Au
80	²⁰⁴Hg	²¹⁵Hg
81	²⁰⁵Tl	²¹⁵Tl
82	²⁰⁶Pb	²¹⁵Pb
83	²⁰⁷Bi	²¹⁵Bi
84	²⁰⁸Po	²¹⁵Po
85	²⁰⁹At	²¹⁵At
86	²¹⁰Rn	²¹⁵Rn
87	²¹¹Fr	²¹⁵Fr
88	²¹²Ra	²¹⁵Ra
89	²¹³Ac	²¹⁵Ac
90	²¹⁴Th	²¹⁵Th
91	²¹⁵Pa	²¹⁵Pa
92	²¹⁶U	²¹⁵U

External data and identifiers

Adopted Levels, Gammas:NuDat 215Pa

Literature and References

[1] - K.-H. Schmidt, W. Faust, G. Münzenberg et al.:
Alpha decay properties of new protactinium isotopes.
In: Nuclear Physics A, 318, 1-2, (1979), DOI 10.1016/0375-9474(79)90482-2.