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放射性同位体とその半減期 - JSON
放射性同位体（放射性核種）は、不安定な原子核を持ち、放射線を放出しながら別の元素に変化する同位体です。半減期とは、放射性物質の量が初期の半分になるまでにかかる時間であり、数ミリ秒から数十億年にわたる極めて広い範囲を持ちます。本データセットは、医学、工業、環境科学、考古学など様々な分野で利用される主要な放射性同位体とその半減期を網羅したものです。
放射性同位体
半減期
放射線
原子核
崩壊
核医学
年代測定
[
{
"code": "001",
"slug": "tellurium-128",
"name": "テルル-128",
"symbol": "Te-128",
"atomicNumber": 52,
"massNumber": 128,
"halfLife": {
"value": 2.2,
"unit": "×10²⁴ years",
"seconds": 6.94e+31
},
"decayMode": "double beta decay",
"category": "naturally-occurring",
"description": "現在知られている中で最も長い半減期を持つ放射性同位体です。"
},
{
"code": "002",
"slug": "xenon-136",
"name": "キセノン-136",
"symbol": "Xe-136",
"atomicNumber": 54,
"massNumber": 136,
"halfLife": {
"value": 2.38,
"unit": "×10²¹ years",
"seconds": 7.51e+28
},
"decayMode": "double beta decay",
"category": "naturally-occurring",
"description": "二重ベータ崩壊を起こす希ガス元素の同位体です。"
},
{
"code": "003",
"slug": "thorium-232",
"name": "トリウム-232",
"symbol": "Th-232",
"atomicNumber": 90,
"massNumber": 232,
"halfLife": {
"value": 1.41,
"unit": "×10¹⁰ years",
"seconds": 445000000000000000
},
"decayMode": "alpha decay",
"category": "naturally-occurring",
"description": "トリウム系列の親核種であり、地球に豊富に存在する放射性元素です。"
},
{
"code": "004",
"slug": "uranium-238",
"name": "ウラン-238",
"symbol": "U-238",
"atomicNumber": 92,
"massNumber": 238,
"halfLife": {
"value": 4.47,
"unit": "×10⁹ years",
"seconds": 141000000000000000
},
"decayMode": "alpha decay",
"category": "naturally-occurring",
"description": "天然ウランの主要構成成分であり、ウラン系列の親核種です。"
},
{
"code": "005",
"slug": "potassium-40",
"name": "カリウム-40",
"symbol": "K-40",
"atomicNumber": 19,
"massNumber": 40,
"halfLife": {
"value": 1.26,
"unit": "×10⁹ years",
"seconds": 39800000000000000
},
"decayMode": "beta decay / electron capture",
"category": "naturally-occurring",
"description": "カリウムの放射性同位体で、岩石年代測定に広く利用されます。"
},
{
"code": "006",
"slug": "uranium-235",
"name": "ウラン-235",
"symbol": "U-235",
"atomicNumber": 92,
"massNumber": 235,
"halfLife": {
"value": 7.04,
"unit": "×10⁸ years",
"seconds": 22200000000000000
},
"decayMode": "alpha decay",
"category": "naturally-occurring",
"description": "核分裂性を持ち、原子力発電の主要燃料です。"
},
{
"code": "007",
"slug": "plutonium-244",
"name": "プルトニウム-244",
"symbol": "Pu-244",
"atomicNumber": 94,
"massNumber": 244,
"halfLife": {
"value": 8.26,
"unit": "×10⁷ years",
"seconds": 2610000000000000
},
"decayMode": "alpha decay",
"category": "transuranic",
"description": "最も長い半減期を持つプルトニウムの同位体です。"
},
{
"code": "008",
"slug": "iodine-129",
"name": "ヨウ素-129",
"symbol": "I-129",
"atomicNumber": 53,
"massNumber": 129,
"halfLife": {
"value": 1.57,
"unit": "×10⁷ years",
"seconds": 495000000000000
},
"decayMode": "beta decay",
"category": "fission-product",
"description": "長寿命核分裂生成物で、地質学的年代測定に利用されます。"
},
{
"code": "009",
"slug": "aluminum-26",
"name": "アルミニウム-26",
"symbol": "Al-26",
"atomicNumber": 13,
"massNumber": 26,
"halfLife": {
"value": 7.17,
"unit": "×10⁵ years",
"seconds": 22600000000000
},
"decayMode": "beta decay / electron capture",
"category": "cosmogenic",
"description": "宇宙線によって生成され、隕石年代測定に利用されます。"
},
{
"code": "010",
"slug": "carbon-14",
"name": "炭素-14",
"symbol": "C-14",
"atomicNumber": 6,
"massNumber": 14,
"halfLife": {
"value": 5730,
"unit": "years",
"seconds": 181000000000
},
"decayMode": "beta decay",
"category": "cosmogenic",
"description": "放射性炭素年代測定法の基礎となる最も有名な同位体です。"
},
{
"code": "011",
"slug": "plutonium-239",
"name": "プルトニウム-239",
"symbol": "Pu-239",
"atomicNumber": 94,
"massNumber": 239,
"halfLife": {
"value": 24100,
"unit": "years",
"seconds": 761000000000
},
"decayMode": "alpha decay",
"category": "transuranic",
"description": "核分裂性を持ち、原子力発電と核兵器の両方に使用されます。"
},
{
"code": "012",
"slug": "americium-241",
"name": "アメリシウム-241",
"symbol": "Am-241",
"atomicNumber": 95,
"massNumber": 241,
"halfLife": {
"value": 432.2,
"unit": "years",
"seconds": 13600000000
},
"decayMode": "alpha decay",
"category": "transuranic",
"description": "煙感知器に広く使用される人工放射性元素です。"
},
{
"code": "013",
"slug": "radium-226",
"name": "ラジウム-226",
"symbol": "Ra-226",
"atomicNumber": 88,
"massNumber": 226,
"halfLife": {
"value": 1600,
"unit": "years",
"seconds": 50500000000
},
"decayMode": "alpha decay",
"category": "naturally-occurring",
"description": "キュリー夫人によって発見され、かつて医療に使用された有名な放射性元素です。"
},
{
"code": "014",
"slug": "cesium-137",
"name": "セシウム-137",
"symbol": "Cs-137",
"atomicNumber": 55,
"massNumber": 137,
"halfLife": {
"value": 30.17,
"unit": "years",
"seconds": 952000000
},
"decayMode": "beta decay",
"category": "fission-product",
"description": "核分裂生成物で、医療と工業に利用されると同時に環境汚染の懸念もあります。"
},
{
"code": "015",
"slug": "strontium-90",
"name": "ストロンチウム-90",
"symbol": "Sr-90",
"atomicNumber": 38,
"massNumber": 90,
"halfLife": {
"value": 28.8,
"unit": "years",
"seconds": 909000000
},
"decayMode": "beta decay",
"category": "fission-product",
"description": "骨に取り込まれやすい核分裂生成物で、環境モニタリングの重要対象です。"
},
{
"code": "016",
"slug": "tritium",
"name": "トリチウム（三重水素）",
"symbol": "H-3",
"atomicNumber": 1,
"massNumber": 3,
"halfLife": {
"value": 12.3,
"unit": "years",
"seconds": 388000000
},
"decayMode": "beta decay",
"category": "cosmogenic",
"description": "水素の放射性同位体で、核融合研究や時計の発光塗料に使用されます。"
},
{
"code": "017",
"slug": "cobalt-60",
"name": "コバルト-60",
"symbol": "Co-60",
"atomicNumber": 27,
"massNumber": 60,
"halfLife": {
"value": 5.27,
"unit": "years",
"seconds": 166000000
},
"decayMode": "beta decay",
"category": "artificial",
"description": "がん治療用の放射線源として広く使用される人工放射性同位体です。"
},
{
"code": "018",
"slug": "iridium-192",
"name": "イリジウム-192",
"symbol": "Ir-192",
"atomicNumber": 77,
"massNumber": 192,
"halfLife": {
"value": 73.8,
"unit": "days",
"seconds": 6380000
},
"decayMode": "beta decay",
"category": "artificial",
"description": "工業用放射線透過試験に広く使用されるガンマ線源です。"
},
{
"code": "019",
"slug": "iodine-131",
"name": "ヨウ素-131",
"symbol": "I-131",
"atomicNumber": 53,
"massNumber": 131,
"halfLife": {
"value": 8.04,
"unit": "days",
"seconds": 695000
},
"decayMode": "beta decay",
"category": "fission-product",
"description": "甲状腺の診断と治療に使用される核医学用放射性同位体です。"
},
{
"code": "020",
"slug": "molybdenum-99",
"name": "モリブデン-99",
"symbol": "Mo-99",
"atomicNumber": 42,
"massNumber": 99,
"halfLife": {
"value": 65.9,
"unit": "hours",
"seconds": 237000
},
"decayMode": "beta decay",
"category": "fission-product",
"description": "テクネチウム-99mの親核種であり、核医学診断の基盤となります。"
},
{
"code": "021",
"slug": "technetium-99m",
"name": "テクネチウム-99m",
"symbol": "Tc-99m",
"atomicNumber": 43,
"massNumber": 99,
"halfLife": {
"value": 6.01,
"unit": "hours",
"seconds": 21600
},
"decayMode": "isomeric transition",
"category": "artificial",
"description": "核医学診断で最も広く使用される放射性同位体です。"
},
{
"code": "022",
"slug": "fluorine-18",
"name": "フッ素-18",
"symbol": "F-18",
"atomicNumber": 9,
"massNumber": 18,
"halfLife": {
"value": 109.8,
"unit": "minutes",
"seconds": 6588
},
"decayMode": "positron emission",
"category": "artificial",
"description": "PET検査で使用される陽電子放出核種です。"
},
{
"code": "023",
"slug": "radon-222",
"name": "ラドン-222",
"symbol": "Rn-222",
"atomicNumber": 86,
"massNumber": 222,
"halfLife": {
"value": 3.82,
"unit": "days",
"seconds": 330000
},
"decayMode": "alpha decay",
"category": "naturally-occurring",
"description": "室内空気汚染の原因となる自然発生の放射性ガスです。"
},
{
"code": "024",
"slug": "polonium-210",
"name": "ポロニウム-210",
"symbol": "Po-210",
"atomicNumber": 84,
"massNumber": 210,
"halfLife": {
"value": 138.4,
"unit": "days",
"seconds": 12000000
},
"decayMode": "alpha decay",
"category": "naturally-occurring",
"description": "強いアルファ線を放出し、かつては静電気除去装置に使用されました。"
},
{
"code": "025",
"slug": "bismuth-213",
"name": "ビスマス-213",
"symbol": "Bi-213",
"atomicNumber": 83,
"massNumber": 213,
"halfLife": {
"value": 45.6,
"unit": "minutes",
"seconds": 2736
},
"decayMode": "beta decay / alpha decay",
"category": "artificial",
"description": "標的放射性核種治療に使用されるアルファ線源です。"
},
{
"code": "026",
"slug": "actinium-225",
"name": "アクチニウム-225",
"symbol": "Ac-225",
"atomicNumber": 89,
"massNumber": 225,
"halfLife": {
"value": 9.9,
"unit": "days",
"seconds": 855000
},
"decayMode": "alpha decay",
"category": "artificial",
"description": "標的アルファ治療に使用される有望な放射性同位体です。"
},
{
"code": "027",
"slug": "lutetium-177",
"name": "ルテチウム-177",
"symbol": "Lu-177",
"atomicNumber": 71,
"massNumber": 177,
"halfLife": {
"value": 6.65,
"unit": "days",
"seconds": 575000
},
"decayMode": "beta decay",
"category": "artificial",
"description": "神経内分泌腫瘍の治療に使用されるベータ線源です。"
},
{
"code": "028",
"slug": "yttrium-90",
"name": "イットリウム-90",
"symbol": "Y-90",
"atomicNumber": 39,
"massNumber": 90,
"halfLife": {
"value": 64.1,
"unit": "hours",
"seconds": 231000
},
"decayMode": "beta decay",
"category": "fission-product",
"description": "肝がん治療（SIRT）に使用されるベータ線源です。"
},
{
"code": "029",
"slug": "phosphorus-32",
"name": "リン-32",
"symbol": "P-32",
"atomicNumber": 15,
"massNumber": 32,
"halfLife": {
"value": 14.3,
"unit": "days",
"seconds": 1240000
},
"decayMode": "beta decay",
"category": "artificial",
"description": "悪性腫瘍の治療と生物学研究に使用されます。"
},
{
"code": "030",
"slug": "sodium-24",
"name": "ナトリウム-24",
"symbol": "Na-24",
"atomicNumber": 11,
"massNumber": 24,
"halfLife": {
"value": 15,
"unit": "hours",
"seconds": 54000
},
"decayMode": "beta decay",
"category": "artificial",
"description": "血流測定や工業用流量測定に使用されます。"
},
{
"code": "031",
"slug": "gallium-68",
"name": "ガリウム-68",
"symbol": "Ga-68",
"atomicNumber": 31,
"massNumber": 68,
"halfLife": {
"value": 68,
"unit": "minutes",
"seconds": 4080
},
"decayMode": "positron emission",
"category": "artificial",
"description": "PET検査で使用される陽電子放出核種です。"
},
{
"code": "032",
"slug": "copper-64",
"name": "銅-64",
"symbol": "Cu-64",
"atomicNumber": 29,
"massNumber": 64,
"halfLife": {
"value": 12.7,
"unit": "hours",
"seconds": 45720
},
"decayMode": "beta decay / positron emission / electron capture",
"category": "artificial",
"description": "PET画像診断と放射性核種治療の両方に使用される多目的核種です。"
},
{
"code": "033",
"slug": "astatine-211",
"name": "アスタチン-211",
"symbol": "At-211",
"atomicNumber": 85,
"massNumber": 211,
"halfLife": {
"value": 7.2,
"unit": "hours",
"seconds": 25920
},
"decayMode": "alpha decay / electron capture",
"category": "artificial",
"description": "標的アルファ治療に使用される希少なハロゲン元素です。"
},
{
"code": "034",
"slug": "lead-212",
"name": "鉛-212",
"symbol": "Pb-212",
"atomicNumber": 82,
"massNumber": 212,
"halfLife": {
"value": 10.6,
"unit": "hours",
"seconds": 38160
},
"decayMode": "beta decay",
"category": "naturally-occurring",
"description": "トロウ系列の中間核種で、標的放射性核種治療に使用されます。"
},
{
"code": "035",
"slug": "thorium-229",
"name": "トリウム-229",
"symbol": "Th-229",
"atomicNumber": 90,
"massNumber": 229,
"halfLife": {
"value": 7340,
"unit": "years",
"seconds": 232000000000
},
"decayMode": "alpha decay",
"category": "naturally-occurring",
"description": "核時計の研究に使用されるトリウムの同位体です。"
},
{
"code": "036",
"slug": "protactinium-231",
"name": "プロトアクチニウム-231",
"symbol": "Pa-231",
"atomicNumber": 91,
"massNumber": 231,
"halfLife": {
"value": 32760,
"unit": "years",
"seconds": 1030000000000
},
"decayMode": "alpha decay",
"category": "naturally-occurring",
"description": "海洋循環の年代測定に使用される長寿命放射性核種です。"
},
{
"code": "037",
"slug": "neptunium-237",
"name": "ネプツニウム-237",
"symbol": "Np-237",
"atomicNumber": 93,
"massNumber": 237,
"halfLife": {
"value": 2.14,
"unit": "×10⁶ years",
"seconds": 67500000000000
},
"decayMode": "alpha decay",
"category": "transuranic",
"description": "ネプツニウム系列の親核種であり、使用済み核燃料中に存在します。"
},
{
"code": "038",
"slug": "curium-247",
"name": "キュリウム-247",
"symbol": "Cm-247",
"atomicNumber": 96,
"massNumber": 247,
"halfLife": {
"value": 1.56,
"unit": "×10⁷ years",
"seconds": 492000000000000
},
"decayMode": "alpha decay",
"category": "transuranic",
"description": "最も長い半減期を持つキュリウムの同位体です。"
},
{
"code": "039",
"slug": "einsteinium-252",
"name": "アインスタイニウム-252",
"symbol": "Es-252",
"atomicNumber": 99,
"massNumber": 252,
"halfLife": {
"value": 471.7,
"unit": "days",
"seconds": 40800000
},
"decayMode": "alpha decay",
"category": "transuranic",
"description": "最も長い半減期を持つアインスタイニウムの同位体です。"
},
{
"code": "040",
"slug": "californium-251",
"name": "カリホルニウム-251",
"symbol": "Cf-251",
"atomicNumber": 98,
"massNumber": 251,
"halfLife": {
"value": 898,
"unit": "years",
"seconds": 28300000000
},
"decayMode": "alpha decay",
"category": "transuranic",
"description": "最も長い半減期を持つカリホルニウムの同位体です。"
}
]