Isotopes of calcium

Calcium ({{sub|20}}Ca) has 26 known isotopes, ranging from {{sup|35}}Ca to {{sup|60}}Ca. There are five stable isotopes ({{sup|40}}Ca, {{sup|42}}Ca, {{sup|43}}Ca, {{sup|44}}Ca and {{sup|46}}Ca), plus one isotope ({{sup|48}}Ca) with such a long half-life that it is for all practical purposes stable. The most abundant isotope, {{sup|40}}Ca, as well as the rare {{sup|46}}Ca, are theoretically unstable on energetic grounds, but their decay has not been observed. Calcium also has a cosmogenic isotope, {{sup|41}}Ca, with half-life 99,400 years. Unlike cosmogenic isotopes produced in the air, {{sup|41}}Ca is produced by neutron activation of solid {{sup|40}}Ca in rock and soil. Most of its production is in the upper metre of the soil column, where the cosmogenic neutron flux is still strong enough.  The most stable artificial isotopes are {{sup|45}}Ca with half-life 162.61 days and {{sup|47}}Ca with half-life 4.536 days. All other calcium isotopes have half-lives of minutes or less.

{{sup|40}}Ca comprises about 97% of natural calcium and is mainly created by nucleosynthesis in stars (alpha process). Like {{sup|40}}Ar, however, some {{sup|40}}Ca is radiogenic, created by radioactive decay of {{sup|40}}K. While K–Ar dating has been used extensively in the geological sciences, the prevalence of {{sup|40}}Ca in nature initially impeded the proliferation of K-Ca dating in early studies, with only a handful of studies in the 20th century. Modern techniques using increasingly precise Thermal-Ionization (TIMS) and Collision-Cell Multi-Collector Inductively-coupled plasma mass spectrometry (CC-MC-ICP-MS) techniques, however, have been used for successful K–Ca dating<ref>{{Cite journal |last1=Marshall |first1=B. D. |last2=DePaolo |first2=D. J. |date=1982-12-01 |title=Precise age determinations and petrogenetic studies using the KCa method |journal=Geochimica et Cosmochimica Acta |volume=46 |issue=12 |pages=2537–2545 |doi=10.1016/0016-7037(82)90376-3 |bibcode=1982GeCoA..46.2537M |issn=0016-7037}}{{clarify|reason=what is the unicode private-use character in |title= (U+E5F8) supposed to be? |date=September 2025}}</ref><ref>{{Cite journal |last=admin |title=K-Ca dating and Ca isotope composition of the oldest Solar System lava, Erg Chech 002 |journal=Geochemical Perspectives Letters |date=18 January 2023 |volume=24 |issue=24 |pages=33–37 |doi=10.7185/geochemlet.2302 |bibcode=2023GChPL..24...33D |url=https://www.geochemicalperspectivesletters.org/article2302/ |access-date=2024-10-16 |language=en-US|doi-access=free }}</ref> similar in method to Rb-Sr dating, as well as determining K losses from the lower continental crust<ref>{{Cite journal |last=admin |title=Radiogenic Ca isotopes confirm post-formation K depletion of lower crust {{!}} Geochemical Perspectives Letters |journal=Geochemical Perspectives Letters |date=6 February 2019 |volume=9 |issue=9 |pages=43–48 |url=https://www.geochemicalperspectivesletters.org/article1904/ |access-date=2024-10-16 |language=en-US}}</ref> and for source-tracing calcium contributions from various geologic reservoirs.<ref>{{Cite journal |last1=Antonelli |first1=Michael A. |last2=DePaolo |first2=Donald J. |last3=Christensen |first3=John N. |last4=Wotzlaw |first4=Jörn-Frederik |last5=Pester |first5=Nicholas J. |last6=Bachmann |first6=Olivier |date=2021-09-16 |title=Radiogenic 40 Ca in Seawater: Implications for Modern and Ancient Ca Cycles |url=https://pubs.acs.org/doi/10.1021/acsearthspacechem.1c00179 |journal=ACS Earth and Space Chemistry |language=en |volume=5 |issue=9 |pages=2481–2492 |doi=10.1021/acsearthspacechem.1c00179 |bibcode=2021ESC.....5.2481A |osti=1859027 |issn=2472-3452|url-access=subscription }}</ref><ref>{{Cite journal |last1=Davenport |first1=Jesse |last2=Caro |first2=Guillaume |last3=France-Lanord |first3=Christian |date=2022-12-01 |title=Decoupling of physical and chemical erosion in the Himalayas revealed by radiogenic Ca isotopes |journal=Geochimica et Cosmochimica Acta |volume=338 |pages=199–219 |doi=10.1016/j.gca.2022.10.031 |bibcode=2022GeCoA.338..199D |issn=0016-7037|doi-access=free }}</ref>

Stable isotope variations of calcium (most typically {{sup|44}}Ca/{{sup|40}}Ca or {{sup|44}}Ca/{{sup|42}}Ca, denoted 'δ{{sup|44}}Ca' and 'δ{{sup|44/42}}Ca' in delta notation) are also widely used across the natural sciences for a number of applications, ranging from early determination of osteoporosis<ref>{{Cite journal |last1=Eisenhauer |first1=A. |last2=Müller |first2=M. |last3=Heuser |first3=A. |last4=Kolevica |first4=A. |last5=Glüer |first5=C. -C. |last6=Both |first6=M. |last7=Laue |first7=C. |last8=Hehn |first8=U. v. |last9=Kloth |first9=S. |last10=Shroff |first10=R. |last11=Schrezenmeir |first11=J. |date=2019-06-01 |title=Calcium isotope ratios in blood and urine: A new biomarker for the diagnosis of osteoporosis |journal=Bone Reports |volume=10 |article-number=100200 |doi=10.1016/j.bonr.2019.100200 |pmid=30997369 |pmc=6453776 |issn=2352-1872}}</ref> to quantifying volcanic eruption timescales.<ref>{{Cite journal |last1=Antonelli |first1=Michael A. |last2=Mittal |first2=Tushar |last3=McCarthy |first3=Anders |last4=Tripoli |first4=Barbara |last5=Watkins |first5=James M. |last6=DePaolo |first6=Donald J. |date=2019-10-08 |title=Ca isotopes record rapid crystal growth in volcanic and subvolcanic systems |journal=Proceedings of the National Academy of Sciences |language=en |volume=116 |issue=41 |pages=20315–20321 |doi=10.1073/pnas.1908921116 |doi-access=free |issn=0027-8424 |pmc=6789932 |pmid=31548431 |bibcode=2019PNAS..11620315A }}</ref> Other applications include: quantifying carbon sequestration efficiency in CO<sub>2</sub> injection sites<ref>{{Cite journal |last1=Pogge von Strandmann |first1=Philip A. E. |last2=Burton |first2=Kevin W. |last3=Snæbjörnsdóttir |first3=Sandra O. |last4=Sigfússon |first4=Bergur |last5=Aradóttir |first5=Edda S. |last6=Gunnarsson |first6=Ingvi |last7=Alfredsson |first7=Helgi A. |last8=Mesfin |first8=Kiflom G. |last9=Oelkers |first9=Eric H. |last10=Gislason |first10=Sigurður R. |date=2019-04-30 |title=Rapid CO2 mineralisation into calcite at the CarbFix storage site quantified using calcium isotopes |journal=Nature Communications |language=en |volume=10 |issue=1 |page=1983 |doi=10.1038/s41467-019-10003-8 |pmid=31040283 |pmc=6491611 |issn=2041-1723}}</ref> and understanding ocean acidification,<ref>{{Cite journal |last1=Fantle |first1=Matthew S. |last2=Ridgwell |first2=Andy |date=2020-08-05 |title=Towards an understanding of the Ca isotopic signal related to ocean acidification and alkalinity overshoots in the rock record |journal=Chemical Geology |volume=547 |article-number=119672 |doi=10.1016/j.chemgeo.2020.119672 |bibcode=2020ChGeo.54719672F |issn=0009-2541|doi-access=free }}</ref> exploring both ubiquitous and rare magmatic processes, such as formation of granites<ref>{{Cite journal |last1=Antonelli |first1=Michael A. |last2=Yakymchuk |first2=Chris |last3=Schauble |first3=Edwin A. |last4=Foden |first4=John |last5=Janoušek |first5=Vojtěch |last6=Moyen |first6=Jean-François |last7=Hoffmann |first7=Jan |last8=Moynier |first8=Frédéric |last9=Bachmann |first9=Olivier |date=2023-04-15 |title=Granite petrogenesis and the δ44Ca of continental crust |url=https://www.sciencedirect.com/science/article/pii/S0012821X23000936 |journal=Earth and Planetary Science Letters |volume=608 |article-number=118080 |doi=10.1016/j.epsl.2023.118080 |issn=0012-821X|hdl=20.500.11850/603069 |hdl-access=free }}</ref> and carbonatites,<ref>{{Cite journal |last=admin |title=Calcium isotope fractionation during melt immiscibility and carbonatite petrogenesis {{!}} Geochemical Perspectives Letters |journal=Geochemical Perspectives Letters |date=December 2023 |volume=28 |issue=28 |pages=13–19 |doi=10.7185/geochemlet.2338 |url=https://www.geochemicalperspectivesletters.org/article2338/ |access-date=2024-10-16 |language=en-US|doi-access=free |hdl=20.500.11850/662437 |hdl-access=free }}</ref> tracing modern and ancient trophic webs including in dinosaurs,<ref>{{Cite journal |last1=Skulan |first1=Joseph |last2=DePaolo |first2=Donald J. |last3=Owens |first3=Thomas L. |date=1997-06-01 |title=Biological control of calcium isotopic abundances in the global calcium cycle |url=https://www.sciencedirect.com/science/article/abs/pii/S0016703797000471 |journal=Geochimica et Cosmochimica Acta |volume=61 |issue=12 |pages=2505–2510 |doi=10.1016/S0016-7037(97)00047-1 |bibcode=1997GeCoA..61.2505S |issn=0016-7037|url-access=subscription }}</ref><ref>{{Cite journal |last=admin |title=Calcium stable isotopes place Devonian conodonts as first level consumers {{!}} Geochemical Perspectives Letters |journal=Geochemical Perspectives Letters |date=26 April 2019 |volume=10 |issue=10 |pages=36–39 |url=https://www.geochemicalperspectivesletters.org/article1912/ |access-date=2024-10-16 |language=en-US}}</ref><ref>{{Cite journal |last1=Hassler |first1=A. |last2=Martin |first2=J. E. |last3=Amiot |first3=R. |last4=Tacail |first4=T. |last5=Godet |first5=F. Arnaud |last6=Allain |first6=R. |last7=Balter |first7=V. |date=2018-04-11 |title=Calcium isotopes offer clues on resource partitioning among Cretaceous predatory dinosaurs |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=285 |issue=1876 |article-number=20180197 |doi=10.1098/rspb.2018.0197 |issn=0962-8452 |pmc=5904318 |pmid=29643213}}</ref> assessing weaning practices in ancient humans,<ref>{{Cite journal |last1=Tacail |first1=Théo |last2=Thivichon-Prince |first2=Béatrice |last3=Martin |first3=Jeremy E. |last4=Charles |first4=Cyril |last5=Viriot |first5=Laurent |last6=Balter |first6=Vincent |date=2017-06-13 |title=Assessing human weaning practices with calcium isotopes in tooth enamel |journal=Proceedings of the National Academy of Sciences |language=en |volume=114 |issue=24 |pages=6268–6273 |doi=10.1073/pnas.1704412114 |doi-access=free |issn=0027-8424 |pmc=5474782 |pmid=28559355 |bibcode=2017PNAS..114.6268T }}</ref> and a plethora of other emerging applications.

== List of isotopes == {{Anchor|Calcium-33|Calcium-34|Calcium-61}}

{{Isotopes table |symbol=Ca |refs=NUBASE2020, AME2020 II, IsotopeFRIB |notes=mass#, unc(), var[], spin(), spin#, hl-nst, daughter-st, EC, n, p, discoveryname }} |-id=Calcium-35 | rowspan=3|{{sup|35}}Ca | rowspan=3 style="text-align:right" | 20 | rowspan=3 style="text-align:right" | 15 | rowspan=3|35.00557(22)# | rowspan=3 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/35.pdf 1985] | rowspan=3|25.7(2) ms | β{{sup|+}}, p (95.8%) | {{sup|34}}Ar | rowspan=3|1/2+# | rowspan=3| | rowspan=3| |- | β{{sup|+}}, 2p (4.2%) | {{sup|33}}Cl |- | β{{sup|+}} (rare) | {{sup|35}}K |-id=Calcium-36 | rowspan=2|{{sup|36}}Ca | rowspan=2 style="text-align:right" | 20 | rowspan=2 style="text-align:right" | 16 | rowspan=2|35.993074(43) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/36.pdf 1977] | rowspan=2|100.9(13) ms | β{{sup|+}}, p (51.2%) | {{sup|35}}Ar | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β{{sup|+}} (48.8%) | {{sup|36}}K |-id=Calcium-37 | rowspan=2|{{sup|37}}Ca | rowspan=2 style="text-align:right" | 20 | rowspan=2 style="text-align:right" | 17 | rowspan=2|36.98589785(68) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/37.pdf 1964] | rowspan=2|181.0(9) ms | β{{sup|+}}, p (76.8%) | '''{{sup|36}}Ar''' | rowspan=2|3/2+ | rowspan=2| | rowspan=2| |- | β{{sup|+}} (23.2%) | {{sup|37}}K |-id=Calcium-38 | {{sup|38}}Ca | style="text-align:right" | 20 | style="text-align:right" | 18 | 37.97631922(21) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/38.pdf 1966] | 443.70(25) ms | β{{sup|+}} | {{sup|38}}K | 0+ | | |-id=Calcium-39 | {{sup|39}}Ca | style="text-align:right" | 20 | style="text-align:right" | 19 | 38.97071081(64) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/39.pdf 1943] | 860.3(8) ms | β{{sup|+}} | '''{{sup|39}}K''' | 3/2+ | | |-id=Calcium-40 | {{sup|40}}Ca<ref group="n">Heaviest observationally stable nuclide with equal numbers of protons and neutrons</ref> | style="text-align:right" | 20 | style="text-align:right" | 20 | 39.962590850(22) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/40.pdf 1922] | colspan=3 align=center|'''Observationally stable'''<ref group="n">Believed to undergo double electron capture to '''{{sup|40}}Ar''' with a half-life no less than 10{{sup|22}} y</ref> | 0+ | 0.9694(16) | 0.96933–0.96947 |-id=Calcium-41 | {{sup|41}}Ca | style="text-align:right" | 20 | style="text-align:right" | 21 | 40.96227791(15) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/41.pdf 1939] | 9.94(15)×10{{sup|4}} y | EC | '''{{sup|41}}K''' | 7/2− | Trace<ref group="n">Cosmogenic nuclide</ref> | |-id=Calcium-42 | {{sup|42}}Ca | style="text-align:right" | 20 | style="text-align:right" | 22 | 41.95861778(16) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/42.pdf 1934] | colspan=3 align=center|'''Stable''' | 0+ | 0.00647(23) | 0.00646–0.00648 |-id=Calcium-43 | {{sup|43}}Ca | style="text-align:right" | 20 | style="text-align:right" | 23 | 42.95876638(24) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/43.pdf 1934] | colspan=3 align=center|'''Stable''' | 7/2− | 0.00135(10) | 0.00135–0.00135 |-id=Calcium-44 | {{sup|44}}Ca | style="text-align:right" | 20 | style="text-align:right" | 24 | 43.95548149(35) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/44.pdf 1922] | colspan=3 align=center|'''Stable''' | 0+ | 0.0209(11) | 0.02082–0.02092 |-id=Calcium-45 | {{sup|45}}Ca | style="text-align:right" | 20 | style="text-align:right" | 25 | 44.95618627(39) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/45.pdf 1940] | 162.61(9) d | β{{sup|−}} | '''{{sup|45}}Sc''' | 7/2− | | |-id=Calcium-46 | {{sup|46}}Ca | style="text-align:right" | 20 | style="text-align:right" | 26 | 45.9536877(24) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/46.pdf 1938] | colspan=3 align=center|'''Observationally stable'''<ref group="n">Believed to undergo β{{sup|−}}β{{sup|−}} decay to '''{{sup|46}}Ti'''</ref> | 0+ | 4×10{{sup|−5}} | 4×10{{sup|−5}}–4×10{{sup|−5}} |-id=Calcium-47 | {{sup|47}}Ca | style="text-align:right" | 20 | style="text-align:right" | 27 | 46.9545411(24) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/47.pdf 1951] | 4.536(3) d | β{{sup|−}} | {{sup|47}}Sc | 7/2− | | |- | {{sup|48}}Ca<ref group="n" name="PN">Primordial radionuclide</ref><ref group="n">Believed to be capable of undergoing triple beta decay with very long partial half-life</ref> | style="text-align:right" | 20 | style="text-align:right" | 28 | 47.952522654(18) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/48.pdf 1938] | '''5.6(10)×10{{sup|19}} y''' | β{{sup|−}}β{{sup|−}}<ref group="n">Lightest nuclide known to undergo double beta decay</ref>{{refn|group="n"|Theorized to also undergo β{{sup|−}} decay to {{sup|48}}Sc with a partial half-life exceeding 1.1{{su|p=+0.8|b=−0.6}}×10{{sup|21}} years<ref name="48Ca-Aunola">{{cite journal |last1=Aunola |first1=M. |last2=Suhonen |first2=J. |last3=Siiskonen |first3=T. |title=Shell-model study of the highly forbidden beta decay {{sup|48}}Ca → {{sup|48}}Sc |date=1999 |journal=EPL |volume=46 |issue=5 |page=577 |doi=10.1209/epl/i1999-00301-2|bibcode=1999EL.....46..577A |s2cid=250836275 }}</ref>}} | '''{{sup|48}}Ti''' | 0+ | 0.00187(21) | 0.00186–0.00188 |-id=Calcium-49 | {{sup|49}}Ca | style="text-align:right" | 20 | style="text-align:right" | 29 | 48.95566263(19) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/49.pdf 1950] | 8.718(6) min | β{{sup|−}} | {{sup|49}}Sc | 3/2− | | |-id=Calcium-50 | {{sup|50}}Ca | style="text-align:right" | 20 | style="text-align:right" | 30 | 49.9574992(17) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/50.pdf 1964] | 13.45(5) s | β{{sup|−}} | {{sup|50}}Sc | 0+ | | |-id=Calcium-51 | {{sup|51}}Ca | style="text-align:right" | 20 | style="text-align:right" | 31 | 50.96099566(56) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/51.pdf 1980] | 10.0(8) s | β{{sup|−}} | {{sup|51}}Sc | 3/2− | | |-id=Calcium-52 | rowspan=2|{{sup|52}}Ca | rowspan=2 style="text-align:right" | 20 | rowspan=2 style="text-align:right" | 32 | rowspan=2|51.96321365(72) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/52.pdf 1985] | rowspan=2|4.6(3) s | β{{sup|−}} (>98%) | {{sup|52}}Sc | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β{{sup|−}}, n (<2%) | {{sup|51}}Sc |-id=Calcium-53 | rowspan=2|{{sup|53}}Ca | rowspan=2 style="text-align:right" | 20 | rowspan=2 style="text-align:right" | 33 | rowspan=2|52.968451(47) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/53.pdf 1983] | rowspan=2|461(90) ms | β{{sup|−}} (60%) | {{sup|53}}Sc | rowspan=2|1/2−# | rowspan=2| | rowspan=2| |- | β{{sup|−}}, n (40%) | {{sup|52}}Sc |-id=Calcium-54 | {{sup|54}}Ca | style="text-align:right" | 20 | style="text-align:right" | 34 | 53.972989(52) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/54.pdf 1997] | 90(6) ms | β{{sup|−}} | {{sup|54}}Sc | 0+ | | |-id=Calcium-55 | {{sup|55}}Ca | style="text-align:right" | 20 | style="text-align:right" | 35 | 54.97998(17) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/55.pdf 1997] | 22(2) ms | β{{sup|−}} | {{sup|55}}Sc | 5/2−# | | |-id=Calcium-56 | {{sup|56}}Ca | style="text-align:right" | 20 | style="text-align:right" | 36 | 55.98550(27) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/56.pdf 1997] | 11(2) ms | β{{sup|−}} | {{sup|56}}Sc | 0+ | | |-id=Calcium-57 | {{sup|57}}Ca | style="text-align:right" | 20 | style="text-align:right" | 37 | 56.99296(43)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/57.pdf 2009] | 8# ms [>620 ns] | | | 5/2−# | | |-id=Calcium-58 | {{sup|58}}Ca | style="text-align:right" | 20 | style="text-align:right" | 38 | 57.99836(54)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/58.pdf 2009] | 4# ms [>620 ns] | | | 0+ | | |-id=Calcium-59 | {{sup|59}}Ca | style="text-align:right" | 20 | style="text-align:right" | 39 | 59.00624(64)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/59.pdf 2018] | 5# ms [>400 ns] | | | 5/2−# | | |- | {{sup|60}}Ca | style="text-align:right" | 20 | style="text-align:right" | 40 | 60.01181(75)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/20/60.pdf 2018] | 2# ms [>400 ns] | | | 0+ | | |-id=Calcium-61 | <sup>61</sup>Ca | style="text-align:right" | 20 | style="text-align:right" | 41 | 61.02041(86)# | style="text-align:center" | (2025)<ref name="tarasov2025">{{cite journal |last1=Tarasov |first1=O. B. |last2=Sherrill |first2=B. M. |last3=Dombos |first3=A. C. |last4=Fukushima |first4=K. |last5=Gade |first5=A. |last6=Haak |first6=K. |last7=Hausmann |first7=M. |last8=Kahl |first8=D. |last9=Kaloyanov |first9=D. |last10=Kwan |first10=E. |last11=Matthews |first11=H. K. |last12=Ostroumov |first12=P. N. |last13=Portillo |first13=M. |last14=Richardson |first14=I. |last15=Smith |first15=M. K. |last16=Watters |first16=S. |title=Discovery of new isotopes in the fragmentation of Se 82 and insights into their production |journal=Physical Review C |date=4 September 2025 |volume=112 |issue=3 |article-number=034604 |doi=10.1103/573p-7fjp}}</ref><ref group="n" name="uc">Discovery of this isotope is unconfirmed</ref> | 1# ms | | | 1/2−# | {{Isotopes table/footer}}

==Calcium-48== {{main|Calcium-48}}

thumb|About 2 g of calcium-48

Calcium-48 is a doubly magic nucleus with 28 neutrons; unusually neutron-rich for a light primordial nucleus. It decays via double beta decay with an extremely long half-life of about 5.6×10{{sup|19}} years, though single beta decay is also theoretically possible. This decay can analyzed with the ''sd'' nuclear shell model, and it is more energetic (4.27 MeV) than any other double beta decay.<ref name="Balysh">{{cite journal | last = Balysh | first = A. | year = 1996 | title = Double Beta Decay of {{sup|48}}Ca | journal = Physical Review Letters | volume = 77 | pages = 5186–5189 | doi = 10.1103/PhysRevLett.77.5186 | pmid = 10062737 | issue = 26 | bibcode=1996PhRvL..77.5186B|arxiv = nucl-ex/9608001 |display-authors=etal}}</ref> It is used as a precursor for neutron-rich<ref>{{cite journal | last = Notani | first = M. | year = 2002 | title = New neutron-rich isotopes, {{sup|34}}Ne, {{sup|37}}Na and {{sup|43}}Si, produced by fragmentation of a 64A MeV {{sup|48}}Ca beam | journal = Physics Letters B | volume = 542 | issue = 1–2 | pages = 49–54 | doi = 10.1016/S0370-2693(02)02337-7 |bibcode = 2002PhLB..542...49N |display-authors=etal}}</ref> and superheavy<ref>{{cite journal | last = Oganessian | first = Yu. Ts. |date=October 2006 | title = Synthesis of the isotopes of elements 118 and 116 in the {{sup|249}}Cf and {{sup|245}}Cm + {{sup|48}}Ca fusion reactions | journal = Physical Review C | volume = 74 |article-number=044602 | doi = 10.1103/PhysRevC.74.044602 | bibcode=2006PhRvC..74d4602O | issue = 4|display-authors=etal| doi-access = free }}</ref> isotopes.

==Calcium-60== Calcium-60 is the heaviest known isotope {{as of|2020|lc=y}}.<ref name="NUBASE2020"/> First observed in 2018 at Riken alongside {{sup|59}}Ca and seven isotopes of other elements,<ref name="riken">{{cite journal |last1=Tarasov |first1=O. B. |last2=Ahn |first2=D. S. |last3=Bazin |first3=D. |last4=Fukuda |first4=N. |last5=Gade |first5=A. |last6=Hausmann |first6=M. |last7=Inabe |first7=N. |last8=Ishikawa |first8=S. |last9=Iwasa |first9=N. |last10=Kawata |first10=K. |last11=Komatsubara |first11=T. |last12=Kubo |first12=T. |last13=Kusaka |first13=K. |last14=Morrissey |first14=D. J. |last15=Ohtake |first15=M. |last16=Otsu |first16=H. |last17=Portillo |first17=M. |last18=Sakakibara |first18=T. |last19=Sakurai |first19=H. |last20=Sato |first20=H. |last21=Sherrill |first21=B. M. |last22=Shimizu |first22=Y. |last23=Stolz |first23=A. |last24=Sumikama |first24=T. |last25=Suzuki |first25=H. |last26=Takeda |first26=H. |last27=Thoennessen |first27=M. |last28=Ueno |first28=H. |last29=Yanagisawa |first29=Y. |last30=Yoshida |first30=K. |title=Discovery of {{sup|60}}Ca and Implications For the Stability of {{sup|70}}Ca |journal=Physical Review Letters |date=11 July 2018 |volume=121 |issue=2 |article-number=022501 |doi=10.1103/PhysRevLett.121.022501 |display-authors=3|doi-access=free |pmid=30085743 }}</ref> its existence suggests that there are additional even-''N'' isotopes of calcium up to at least {{sup|70}}Ca, while {{sup|59}}Ca is probably the last bound isotope with odd ''N''.<ref>{{cite journal |last1=Neufcourt |first1=Léo |last2=Cao |first2=Yuchen |last3=Nazarewicz |first3=Witold |last4=Olsen |first4=Erik |last5=Viens |first5=Frederi |title=Neutron Drip Line in the Ca Region from Bayesian Model Averaging |journal=Physical Review Letters |date=14 February 2019 |volume=122 |issue=6 |article-number=062502 |doi=10.1103/PhysRevLett.122.062502 |pmid=30822058 |arxiv=1901.07632 |display-authors=3 |bibcode=2019PhRvL.122f2502N }}</ref> Earlier predictions had estimated the heaviest even isotope to be at {{sup|60}}Ca, and {{sup|59}}Ca unbound.<ref name="riken"/>

In the neutron-rich region, ''N'' = 40 becomes a magic number, so {{sup|60}}Ca was considered early on to be a possibly doubly magic nucleus, as is observed for the {{sup|68}}Ni isotone.<ref>{{cite journal |last1=Gade |first1=A. |last2=Janssens |first2=R. V. F. |last3=Weisshaar |first3=D. |last4=Brown |first4=B. A. |last5=Lunderberg |first5=E. |last6=Albers |first6=M. |last7=Bader |first7=V. M. |last8=Baugher |first8=T. |last9=Bazin |first9=D. |last10=Berryman |first10=J. S. |last11=Campbell |first11=C. M. |last12=Carpenter |first12=M. P. |last13=Chiara |first13=C. J. |last14=Crawford |first14=H. L. |last15=Cromaz |first15=M. |last16=Garg |first16=U. |last17=Hoffman |first17=C. R. |last18=Kondev |first18=F. G. |last19=Langer |first19=C. |last20=Lauritsen |first20=T. |last21=Lee |first21=I. Y. |last22=Lenzi |first22=S. M. |last23=Matta |first23=J. T. |last24=Nowacki |first24=F. |last25=Recchia |first25=F. |last26=Sieja |first26=K. |last27=Stroberg |first27=S. 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spectroscopic measurements of the nearby nuclides {{sup|56}}Ca, {{sup|58}}Ca, and {{sup|62}}Ti instead predict that it should lie on the island of inversion known to exist around {{sup|64}}Cr.<ref name="62Ti"/><ref name="56,58Ca">{{cite journal |last1=Chen |first1=S. |last2=Browne |first2=F. |last3=Doornenbal |first3=P. |last4=Lee |first4=J. |last5=Obertelli |first5=A. |last6=Tsunoda |first6=Y. |last7=Otsuka |first7=T. |last8=Chazono |first8=Y. |last9=Hagen |first9=G. |last10=Holt |first10=J.D. |last11=Jansen |first11=G.R. |last12=Ogata |first12=K. |last13=Shimizu |first13=N. |last14=Utsuno |first14=Y. |last15=Yoshida |first15=K. |last16=Achouri |first16=N.L. |last17=Baba |first17=H. |last18=Calvet |first18=D. |last19=Château |first19=F. |last20=Chiga |first20=N. |last21=Corsi |first21=A. |last22=Cortés |first22=M.L. |last23=Delbart |first23=A. |last24=Gheller |first24=J.-M. |last25=Giganon |first25=A. |last26=Gillibert |first26=A. |last27=Hilaire |first27=C. |last28=Isobe |first28=T. 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== See also == '''Daughter products other than calcium''' * Isotopes of titanium * Isotopes of scandium * Isotopes of potassium * Isotopes of argon

== References == {{Reflist}}

==Further reading== * C. Michael Hogan. 2010. [http://www.eoearth.org/article/Calcium?topic=49557 ''Calcium''. ed. A. Jorgenson and C. Cleveland. ''Encyclopedia of Earth'', National Council for Science and the Environment, Washington, D.C.]

== External links == *[https://ww.isotopes.gov National Isotope Development Center Official website]{{Dead link|date=February 2023 |bot=InternetArchiveBot |fix-attempted=yes }} *[https://web.archive.org/web/20120506025523/http://ie.lbl.gov/education/parent/Ca_iso.htm Calcium isotopes data from ''The Berkeley Laboratory Isotopes Project's'']

Category:Isotopes of calcium Category:Calcium Calcium