Elementary Particle Physics Basic

Transcription

1 Elementary Particle Physics Basic 2016 Fumihiko Suekane Research Center for Neutrino Science Extension: EPPBSuekane 1 * URL of this lecture: - Cancellation of lecture, Homework notice, etc. - A copy of lecture slides. * Credit and score! 2 homeworks & Attendance record * Need contact? "Research Center for Neutrino Science Phone: suekane@awa.tohoku.ac.jp EPPBSuekane 2

2 (1) Special Lecture %%00HH1144HH>>DDAA550088HH00==33HH>>DDAA55AA8844==33BB00BB:: 0011>>DDCCCC7744DD::DDBB778800==DD224400AAAA440022CC>>AA ==CC00==3300AA4400==GG88>>DDBB0011>>DDCCFF7700CC AA003388>>0022CC88EE88CCHH44EE4400CC))44== BB BB00BBCCDD3344==CC>>55BB228844==224422>>DDAABB44HH>>DD00AA44 BBDD????>>BB4433CC>>00==BBFF44AA55>>AABBDD2277DD44BBCC88>>==BB EPPBSuekane 3 The Great East Japan Earthquake Sendai Fukushima #1 Tokyo , 14:46 A huge earth quake hit the Tohoku area. The moment magnitude = 9.0 (~2x10 18 J), The Epicenter is ~130km from Sendai, The max. seismic intensity = Pref., Few hours after, the huge tsunami attacked the coast line. Near the Sendai airport EPPBSuekane 4

3 A view from my house ( , 7:00) The fire of spilled oil at a port EPPBSuekane 5 We are here! Tsunami (the location is not exact) Fukushima #1 Nuclear Reactor Complex EPPBSuekane 6

4 AA440022CC>>AABB>>55CC7744DD::DDBB778800==DD224400AA??>>FF44AA BBCC00CC88>>==FF44AA DD44CC>>CC7744CCBBDD==008800==3355>>>>FF88==66 44GG??>>BB88>>==BB00==33BB8866== ==CC00>>DD==CC>>55AA003388>>0022CC88EE ==CCBBFF00BBAA444400BB4433>>DDCCBB EPPBSuekane 7 Radiation measurement at Tohoku Univ. Now: ~0.05μSv/h 2011/3/11 3/18 Measured by Drs Tamura and Kanda 4/ EPPBSuekane 8

5 Change of radiation level of Sendai, before and after the accident Measured by a junior high school student radiation level before the accident 素粒子基礎末包 EPPBSuekane Radiation level We are here. 95km unit: µsv/h

6 Sendai city is monitoring the radiation level every month µsv/h < We are here > Sendai Station 0.14-> 0.18-> 0.11-> 0.17-> Purple= measured in How radioactive elements are produced in reactors? Structure of a reactor Fission reaction! heat! Turbine! Electricity Containment Vessel Pressure Vessel Fuel rods Control rods Turbine Generator 2ndary coolant sea water primary coolant Pumps Pressure Control Pool EPPBSuekane 12

7 Radioactive elements were generated in fission reaction. causes next fission (chain reaction) 235 U These are radioactive elements * Energy release= 200MeV/fission = 3.2x10-11 J/fission (1eV=1.6x10-19 J) * For regular power reactor (P=3GW thermal)10 20 [fission/s]! Avogadro number (6x10 23 ) of new elements (fission products) are produced in every 5 min EPPBSuekane 13 DD44II darewow utslv EPPBSuekane 14

8 darewow utslv DD4422>>==BBDD??CC88>>== 5588BBBB88>>==BBBB GGGG 66BBCC>>==HH4400AA 0055DD44DD==88CC11DDAA==BB55>>AAII HH4400AABB!BB44EE44AA00CC>>==BB>>55 ++ **774400CC>>882211>>11>>== 88AA>>BB DDAA==CC>>==HHII::66 ++ **774444==44AA66HH88==AA440022CC>>AA 44==44AA66HH>>5500CC>>882211>> EPPBSuekane 15 **7744CC>>CC00??>>CC44==CC880044==44AA66HH88==00AA440022CC>>AA22>>AA AA440022CC>>AACC>>==BB>> BB00BB>>005588BBBB8844==DD2244DDBB JJJJJJJJJJ!%%44,,&& GG ##!CC>>CC0044==44AA66HH88==00AA440022CC>>AAGG ## The energy of the Tohoku earth quake = magnitude 9.0 =GG ##FF88::88?? AA440022CC>>AA22>>==CC0088==BBCC8844BB>>AA4444==44AA66HH>>55CC7744 **>>77>>::DD4400AACC77DD00::44 **774444==44AA66HH88BBDD2277>>AA44CC7700==CC7700CC88==00==HH BB88==6644==DD224400AAFF4400??>>== EPPBSuekane 16

9 Where radiation and residual heat come from? Example 137 Cs ν ν ν ν Mass number ν ν Fission produces perform β-decays with various lifetime EPPBSuekane 17 List of RI produced by fission reaction 131 I(8days)3.1% 137 Cs (30y)6.15% 90 Sr (29y)5.77% hijfngopc **7744AA4400AA44>>== CC8844β HHBB>>DDAA2244BB88==CC BBBB88>>== EPPBSuekane 18??AA>>33DD22CCBB

10 ((44BB8833DD CC0055CC44AAAA440022CC>>AABB77DDCC33>>FF== **7744>>== CC8844AA003388>>0022CC88EE ==CCBB::4444?? 6644==44AA00CC88==66CC CCCC88BB==442244BBBB00AAHHCC>>22>>>>CC774455DD44 44EE44==0055CC44AACC7744BB77DDCC33>>FF== 4400CC6644==44AA00CC88>>==0055CC44AAAA440022CC>>AABB77DDCC33>>FF== 2400MW1 ureactor2~4) 240MW 24MW At the time when the tsunami hit the reactor, several tens of mega watt of energy was being generated. This heat destroyed the reactors Reactor shut down at the first shake 2.4MW EPPBSuekane Days Still now (5.5years after) MW of heat is being generated. 19 Nuclear reactors were immediately shut down at the first shake. However, the power station lost electricity because the emergency generators were swamped by the tsunami. The water pumps could not be used and the fuel could not be cooled. Finally the cores melted down. The high heat decomposed the water into hydrogen and oxygen and there were hydrogen explosions. A significant amount of radioactive elements were released outside, presumably from cracks of the vessels. From Tokyo Shimbun (Tokyo Newspaper) web page. ( )

11 Application of particle physics: Detection of the location of the fuel debris angle of muon cosmic-ray muon Container Nagoya Univ. muon detector muon radio-graphy 素粒子基礎 末包 21 No debris in :he pressure essel of reactor #2 " melt down 素粒子基礎 末包 22

12 >>88==00==CC((003388>>0022CC88EE444444==CCBB88==CC Cs: τ 1/2 =30y 134Cs: τ 1/2 =2y These γ rays are measured as radioactivity EPPBSuekane 23 Three kinds of radiations (1) α ray Charged heavy particle (=nucleus of 4 He) Stops by a thin paper. (2) β ray Very light charge particle (=electron) Stops by a metal sheet (3) γ ray Neutral massless particle (= high energy photon) Lead or thick iron is necessary to stop it EPPBSuekane 24

13 CCBB>>55AA CC88>>==CC>>77DD00==11>>33HH Radicals! attack DNA Radiation (γ rays) Ionization! Direct damage of DNA >>55&&!00==2244AA AA44EE44==CC88>>==>>5588DD==88CCHHAA44==44FF00>>552244BB44CC EPPBSuekane 25 Unit of Radiation and dose Absorbed Dose(D) Radiation(X) Rentogen Equivalent Man Equivalent Radiation Dose (H) Decay rate Unit Gy (=1J/kg) rad(=0.01gy) C/kg Rentgen(=2.6x10-4 C/kg) rem (=rad biological effect Q) Sv=100rem Bq(=1decay/s) Ci(=3.7x10 10 Bq) Absorption energy by X-ray or γ-ray per unit mass Strength of photon radiation to ionize air of unit mass Q=1 for X-ray, γ-ray, β-ray =20 for n and α Effect to humane body. H=D Q N (correction factor ~1) obsolete obsolete often used # of decays per second. often used For γ-rays, 1Sv=energy absorption of 1J/kg! (0.05µSv/h=87MeV deposit/s)

14 Unit of Radiation and dose In short, * 1 Sv = 1J of radiation energy deposit /kg for γ & β rays. * The radiation (γ-rays from soil) of Sendai now is ~ 0.05µSv/h. * We get ~2.5mSv/year (=0.29µSv/h) from the natural radio activities. (which includes doses from cosmic rays and Rn) EPPBSuekane 27 AA>>55BB))8844EE44AACC44DD44AAAA44 wikipedia Rolf Maximilian Sievert ( ) Swedish Physicists Study of the biological effects of radiation. wikipedia Antoine Henri Becquerel ( ) French Physicists discoverer of radioactivity Nobel laureate, EPPBSuekane 28 28

15 1 Becquerel= 1decay per second: strength of radioactive source N 0 RI with lifetime τ : N( t) = N 0 e ( t τ ) dn( t) = N 0 dt τ e t τ ( decay ratew ) = N t τ Example 1 of sea water contains 6.9x K(τ=1.8x10 9 y) as KCl. Decay rate is 6.9x10 17 /1.8x10 9 [y]/3.7x10 7 [s/y]=10[decay/s] => 1 of sea water contains 10Bq 40 K. ( ) EPPBSuekane 29 Relation between Sv and Bq It depends on RI and conditions. Example Iy Humane body contains 50Bq/kg of 40 K 90% 40 K performs β-decay with average energy 0.65MeV. (Another 10% is electric capture and emits 1.5MeV γhowever most of this γ escapes from the body. v Thus radiation energy deposit per 1kg tissue is, 50[/kg/s]x0.9x0.65MeV=29MeV/s/kg=0.15m[J/kg/y] This corresponds to internal dose of 0.15[mSv/y] = 0.017[µSv/h]. Example II: 50Bq/kg of 137 Cs, average β energy is ~0.25MeV => 0.06m[Sv/y] EPPBSuekane 30

16 Two Kinds of Exposures to Radiation : Internal and External Exposure * External Exposure α-ray and β-ray are absorbed before entering body. Mainly from γ-rays. Generally solid angle is small. External radiation (soil, cosmic ray) * Internal Exposure (more dangerous) Radiation is absorbed for all solid angle. There is no shield between RI and tissue. α-ray & β-ray deposit all energy in body. Mainly from β and α-ray Internal radiation (food, breath) EPPBSuekane EPPBSuekane 32

17 **7744AA4400AA44AA CC88>>==BB88====00CCDDAA44 Ex.yNatural doseuexternal + Internalvy2.5mSv/yu~0.3µSv/hv Regulation for publicy artificial dose <1mSv/yu<0.1µSv/h) Current Sendai externaly 0.4mSv/y (0.05μSv/h) uhttp:// Chest X-ray: 0.1mSv natural dose [msv/y] Cosmic ray ionization neutron Spalltion Terrestrial Origin External Internal Total Largest contribution U-> Rn(gasv Total EPPBSuekane 33 Background radiation (@C building Y2008) 40 K: 1.5MeVγ 208 Tl: 2.6MeVγ Cosmic-ray EPPBSuekane 34

18 ((>>22::BBBB00==33BB00==33BB>>88BB22>>==CC0088==2244AACC0088==00>>DD==CCBB>>55 ++AA00==88DD00==33AA003388>>0022CC88EE44>>CC00BBBB88DD BB88==224422>>==22AA44CC44DDBB44BBBB00==33BB22>>==22AA44CC4400BB>>6644==44AA00CC44 AA CC88>>== **7744BB44((003388>>22CC88EE ==CCBBFF44AA446644==44AA00CC443388== BBDD??44AA==>>EE0044GG??>>BB88>>==BB114455>>AA44CC774422DDAAAA44==CCBBDD==FF00BB 55>>AA >>==HH4400AABB0066>>%%>>BBCC>>55CC7744((7700EE HH4433>>DDCC11DDCC444444==CCBBFF88CC77EE44AAHH>>== AA44BBCC EE44 Previous sun (( CC88>>==55AA>>CC AACC77 SuperNova ~0.4mSv/y The current sun and earth were generated from the remnants BigBang X 10 8 years EPPBSuekane Now 35 Decay Chain of 238 U Rn = Radioactive noble gas Largest natural dose! 1.2mSv/y Rn: (Noble gas) Generated in the decay chain of U and comes out from rocks and soils and concrete into the air. Then taken in lung by breathing EPPBSuekane 36

19 >>BB8822((00HHBBJJ! 1.2mSv/y ))??00AA:: AA 4400BBDDAA44??00AACC CCAA0022:: ==44AA66HHDD>>==BB00CCCC AACC77BBDDAA DDGGII0.01/cm 2 /s ==88CC7788CCBBCC774477DD00==11>>33HH88CC3344??>>BB88CCBBII100MeV **7744>>AA886688==>>55CC774422>>BB8822AA00HHBB88BB==>>CC::==>>FF== CC88BB00==88??>>AACC00==CCBBDD CC>>55BBCCDD33HH EPPBSuekane 37 **7744==00CCDDAA00AA CC88>>==44EE443344??44==33BB774400EE88HH>>== CC7744?? ==3300CC88CCDD3344 /::'##===:/:1#./2#.#2 //:4 /::'##===221#2#.-/ km **7744AA CC88>>==88BB CC ==3300AA4400 ">>BB44>>55))0088>>AABB88BBBB00BB4400FF00CC44AA22>>==CC0088==BB5544FF(( JJ>>BB44>>5588>>CCBB>>55==CC44AA==00CC88>>== CC88BB KK55AA>>22>>BB8822AA00HH JJ>>BB44>>55CC7744BB??002244BBCC00CC88>>==22AA44FF88BBEE44AAHH ))EEHH4400AA >>FF88BBHH>>DDAA22>>DD==CCAAHH EPPBSuekane 38

20 Summary of the Special Lecture ))EE77..##::66//77 (( CC88>>==44==44AA66HH3344??>>BB88CC88>>==88==11>>33HH GGCC44AA==00(( CC88>>==44EE44>>55))44==330088==>>FF88BB JJJJJJII..µ))EE77//II..))EEHH// EE44AA006644==00CCDDAA0033>>BB44II..))EEHH//??DD118822HH00>>FF CC88>>==0033>>BB44 ))EEHH4400AAIIµ))EE77 **7744AA4400AA44BBCC8800==HH00==HHCCAA002244BB>>55CC7744CCBBDD==008800>>==66 CC774422>>00BBCC88==4400==3300BB>>00==HHAA4422>>EE44AAHH445555>>AACCBB00AA44BB4444== CC7744AA44 AA4422>>44==33HH>>DDCC>>EE88BB88CCBBDD2277??002244BBFF778844HH>>DD00AA447744AA44 00==3311AA88==66HH>>DDAA44GG??44AA8844== ::CC>>HH>>DDAA22>>DD==CCAAHH EPPBSuekane 39