Nuclear Structure and Reactions. Brad Sherrill Chief Scientist Facility for Rare Isotope Beams June 2013

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1 Nuclear Structure and Reactions Brad Sherrill Chief Scientist Facility for Rare Isotope Beams June 2013

2 One of HUGS goals is to introduce students to topics of interest in nuclear physics. My lectures will attempt to describe what is interesting in the study of nuclei. Lecture 1: Search for the limits of nuclear binding and production of new isotopes Lecture 2: Attempts to model atomic nuclei I Lecture 3: Attempts to model atomic nuclei II Lecture 4: Nuclear Reactions Outline of my six lectures Lecture 5: The origin of atoms Nuclear Astrophysics I Lecture 6: The origin of atoms Nuclear Astrophysics II It is important for you to ask questions. Sherrill HUGS Lecture 1, Slide 2

3 Nuclear Landscape Chart of the nuclides Black squares are the 263 stable isotopes found in nature (> 1 Gy) Dark green closed area is the region of isotopes observed so far. The limits are not known. Sherrill HUGS Lecture 1, Slide 3

4 How many isotopes are possible? Let s define possible as lasting long enough to make an atom that could react chemically (10-6 s; probably is valid) Neutron drip line 13 C n 20 C 22 C Proton drip line p Mass model 12 C Heaviest elements The claim for up to atomic number 118 has been made at Dubna (Oganessian et al.) Sherrill HUGS Lecture 1, Slide 4

5 Open Questions in the Search for the Limits Open Questions: How many elements can exist? We are up to element 118 and counting. Are there long-lived superheavy elements, with half lives of greater than 1 year? Where are the atoms of the various elements formed in nature? What makes atomic nuclei stable? We know Strong and Electroweak forces are involved, but don t understand how in detail. The inability to answer this question is reflected in our inability to answer the first three questions. Sherrill HUGS Lecture 1, Slide 5

History of Element Discovery 1700+ Rise of modern chemistry Dalton s Atomic Theory India Babylonia Egypt

6 History of Element Discovery Rise of modern chemistry Dalton s Atomic Theory India Babylonia Egypt China Democritus idea of atoms Copper Age Source: Mathematica + Wikipedia Sherrill HUGS Lecture 1, Slide 6

The history of element discovery 1200-2010 Chemistry

Mendeleev s Periodic Table Particle Accelerators

7 The history of element discovery Chemistry Dalton s Atomic Theory Cavendish, Priestly, Scheele, Mendeleev s Periodic Table Particle Accelerators Reactors Time of the Alchemists Future? Sherrill HUGS Lecture 1, Slide 7

8 Result: Periodic Table of the Elements We don t know the limit. Some estimates are that we have discovered only half of the elements, but we don t know. Superheavy: Only stable due to many-body effects Sherrill HUGS Lecture 1, Slide 8

Synthesis of the heaviest elements Recently named elements 114, 116; claims for 113,115,117,118 Z=113 TOF-detectors position sensitive strip detectors 169 veto detectors SH recoil side detectors

9 Synthesis of the heaviest elements Recently named elements 114, 116; claims for 113,115,117,118 Z=113 TOF-detectors position sensitive strip detectors 169 veto detectors SH recoil side detectors gas-filled chamber 48 Ca-ions recoils detector station rotating entrance window 48 Ca+ 237 Np In new element searches fusion happens only 1 in Y Oganessian et al Sherrill HUGS Lecture 1, Slide 9

10 Alpha (α)-decay emission of a Helium nucleus Why not two protons and two neutrons? Beta (β)-decay weak decay of proton (neutron) to a positron and electron neutrino Electron capture atomic electron is captured, anti-electron neutrino emitted Gamma (γ)-decay nucleus de-excites by emission of a photon Internal conversion energy from nuclear transition is carried away by an atomic electron (very important for transitions in heavier nuclei) Cluster Decay for example 14 C Radioactive Decay Spontaneous fission for example 252 Cf decays by breaking into roughly equal mass pieces Proton decay emission of a hydrogen nucleus, p Neutron decay emission of a neutron (observation still controversial) Sherrill HUGS Lecture 1, Slide 10

11 Superheavy Elements Summary Figure adapted from Y. Ogannessian Dubna, RIKEN, GSI, LBL, RiKEN (Japan) 209 Bi + 70 Zn α nuclides α 111/ / s 36. s α α 113/ / s 0.48 s α / / ms α 111/ / ms / / / / / / Ca Bk 109/ ms 109/ s 109/ /278 Sg/ s α Hs/ s / h α 105/ d 107/271 α 104/ /266 α 107/ s α 105/ / / / / / Ca Ra 237 Np 243 Am 242 Pu, 245 Cm 244 Pu, 248 Cm 249 Cf 249 Bk T 1/2 = 320d ORNL High Flux Reactor 102/ Sherrill HUGS Lecture 1, Slide 11

Today s Extremes of Z and A Discovery of

Rev. Lett. 104, 142502 (2010) Phys. Rev.

12 Today s Extremes of Z and A Discovery of Element Bk + 48 Ca 330 days Bk from HFIR Hot cell target prep Collaboration: FLNR (Dubna), ORNL (Oak- Ridge), LLNL (Livermore), IAR (Dmitrovgrad) Vanderbilt University Phys. Rev. Lett. 104, (2010) Phys. Rev. Lett. 108, (2012) Dubna accelerator Sherrill HUGS Lecture 1, Slide 12

Other view above Z=122 all chemistry is the same due to relativistic effects M. Bender et al.

13 The Challenge of Even Higher Atomic Numbers z (fm) E def (MeV) bubble normal band P. Pyykkö: Phys. Chem. Chem. Phys. 13, (2011) Half of chemistry is undiscovered. Other view above Z=122 all chemistry is the same due to relativistic effects M. Bender et al., to be published r (fm) For stability of Z>120 see also Jachimowicz, Kowal, Skalski, PRC 83 (2011) Sherrill HUGS Lecture 1, Slide 13

14 Half-lives of Superheavy Elements 20 1 year Log T α (sec.) α - decay Deformed Shell Spherical Shell Element Ca Cf Neutron number Symbols: exp. values Lines calc. Sobiczewski & Smolanczuk Sherrill HUGS Lecture 1, Slide 14

Discovery of Isotopes Fredrick Soddy Credited with discovery of isotopes Extremely talented chemist who began his career at McGill as a lecturer in 1900 Rutherford came to McGill at the same time.

Rutherford won 1908 Nobel prize "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances (identified α and β radioactivity) Isotopes In 1910 Soddy

15 Discovery of Isotopes Fredrick Soddy Credited with discovery of isotopes Extremely talented chemist who began his career at McGill as a lecturer in 1900 Rutherford came to McGill at the same time. Rutherford needed the help of a Chemist to try to understand radioactivity. Rutherford won 1908 Nobel prize "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances (identified α and β radioactivity) Isotopes In 1910 Soddy found that the mass of lead from thorium decay differed from lead from uranium decay He realized that atoms of a given elements must come in different forms that he called isotopes (Greek for at the same place ) JJ Thompson in 1913 showed the first direct evidence Ne isotopes in cathode ray tube. "Put colloquially, their atoms have identical outsides but different insides. Soddy Nobel Prize Lecture Won Nobel Prize in 1921 for discovery of isotopes McGill Sherrill HUGS Lecture 1, Slide 15

radio-isotopes formed by the transmutation of boron, magnesium and aluminum, the names radionitrogen,

16 First Synthesis of Radioactive Isotopes The first artificial isotopes were produced by F Joliot and I Curie (Nature, 10 Feb 1934 ) by bombarding B, Al, Mg with alpha particles from Po We propose for the new radio-isotopes formed by the transmutation of boron, magnesium and aluminum, the names radionitrogen, radiosilicon, radiophosphorus For this discovery, Curie and Joliot won the Nobel Prize in chemistry in 1935 Sherrill HUGS Lecture 1, Slide 16

17 New isotope discoveries per year First accelerators WWII Fusion evaporation Spallation Reactors Projectile fragmentation Mass spectroscopy Radioactivity Thoennessen and Sherrill, Nature 473 (2011) 25 Sherrill HUGS Lecture 1, Slide 17

Where Are We Now? You can find out at the website www.nndc.bnl.

18 Where Are We Now? You can find out at the website - National Nuclear Data Center Sherrill HUGS Lecture 1, Slide 18

32 per ounce) 20 protons 20 neutrons Expensive Calcium (.

19 Value of Isotopes Some examples of the cost of isotopes May 27 value of Au-197 C$1438/ounce H-3, tritium, isotope of hydrogen $1.1 M/ounce Normal Calcium (Calcium-40 $.32 per ounce) 20 protons 20 neutrons Expensive Calcium (.2% Calcium-48 $7M per ounce) 20 protons 28 neutrons Among most expensive: Berkelium-249 $644M/ounce Sherrill HUGS Lecture 1, Slide 19

20 Goal of Current Isotope Research Normal Calcium (Calcium-40 $.32 per ounce 4 x10 23 atoms) 20 protons 20 neutrons Goal at FRIB: Calcium-60 ($10,000 for 1000 atoms) 20 protons 40 neutrons Sherrill HUGS Lecture 1, Slide 20

21 Isotope Production Scheme Cartoon of the isotope production process projectile fragmentation or fission (Coulomb breakup, transfer, ) projectile target To produce a key nucleus like 122 Zr the production cross section (from 136 Xe) is estimated to be 2x10-18 b (2 attobarns, 2x10-46 m 2 ) Nevertheless with a 136 Xe beam of 8x10 13 ion/s (400 kw at 200 MeV/u) a few atoms per week can be made and studied (>80% collection efficiency) For comparison: Element 117 production cross section was 1.3 ( ) pb (1.3x10-12 b) (Oganessian, Yu. Ts. et al PRL 104 (2010) ) Few x10-46 m 2 is on the order of 100 MeV neutrino-electron elastic scattering cross sections Sherrill HUGS Lecture 1, Slide 21

22 Production and Identification of Isotopes Sometimes looking for 1 event from beam particles Example: 40 Mg Production 120 pna 48 Ca 140 MeV/u Goal was to produce 40 Mg Sherrill HUGS Lecture 1, Slide 22

23 First observation of 40 Mg T. Baumann et al., Nature 449, 1022 (2007) ρ = m v B q tof = dist v ΔE(inmaterial) Z 2 v 2 m q Sherrill HUGS Lecture 1, Slide 23

24 LISE++ Simulation Code The code operates under Windows and provides a highly user-friendly interface. See me at this school for a tutorial session It can be downloaded from the following internet address: O. Tarasov, D. Bazin et al. Sherrill HUGS Lecture 1, Slide 24

25 Production Probability The probability of production of a fragment is related to its production cross section: dn(τ ) dτ = N a σ A t P = N(τ ) N 0 # = 1 e % $ τ N a σ A t For production cross sections of 1 mb and 9 Be target thickness of 1 g/ cm 2 the production probability (and fragment rate) is high: P = N(τ) N 0 = 1 e Beam of /s beam would yield 7x10 9 /s Note: Key is σ cross section, τ target thickness, N 0 beam intensity 9 & ( ' = τ target thickness (g/cm 2 ) N a Avagodro s number A t target mass number σ production cross section Sherrill HUGS Lecture 1, Slide 25

Cross Section for Production Beam Target r b r t 18 O 17 N One nucleon removal Around 50 mb (light nuclei) σ = π( r t + r ) 2 b 600 mb Actual: 16 O + 12 C interaction cross section: 1000 mb (measured

26 Cross Section for Production Beam Target r b r t 18 O 17 N One nucleon removal Around 50 mb (light nuclei) σ = π( r t + r ) 2 b 600 mb Actual: 16 O + 12 C interaction cross section: 1000 mb (measured at 970 MeV/u) Note: Above around 300 MeV/u the interaction length is shorter than the electronic stopping range of the 16 O so most beam particles can interact 16 C 15 B 14 Be 11 Li 1 2 Li 1 3 Li P 5% 2n removal 5 mb P =.5% And so on Rule of thumb.1 x for each neutron removed Sherrill HUGS Lecture 1, Slide 26

27 Production Mechanisms High Energy (more in lecture 4) Fragmentation (FRIB, RIBLL Lanzhou, NSCL, GSI, RIKEN, GANIL) o Projectile fragmentation of high energy (>50 MeV/A) heavy ions o Target fragmentation of a target with high energy protons or light HIs. In the heavy ion reaction mechanism community this would include intermediate mass fragments. Spallation (ISOLDE, TRIUMF-ISAC, EURISOL, SPES, ) o Name comes from spalling or cracking-off of target pieces. o One of the major ISOLDE mechanisms, e.g. 11 Li made from spallation of Uranium. Fission (HRIBF, ARIEL, ISAC, JYFL, BRIF, ) o There is a variety of ways to induce fission (photons, protons, neutrons (thermal, low, high energy) o The fissioning nuclei can be the target (HRIBF, ISAC) or the beam (GSI, NSCL, RIKEN, FAIR, FRIB). Coulomb Breakup (GSI) o At beam velocities of 1 GeV/n the equivalent photon flux as an ion passes a target is so high the GDR excitation cross section is many barns. Sherrill HUGS Lecture 1, Slide 27

Spallation From Wikimedia Commons: http://en.wikipedia.

28 Spallation From Wikimedia Commons: Sherrill HUGS Lecture 1, Slide 28

29 Method of discovery of the isotopes Sherrill HUGS Lecture 1, Slide 29

Major US Project Facility for Rare Isotope Beams, FRIB Funded by DOE Office of Science 2020 completion Key Feature is 400kW beam power (5 x10 13 238

30 Major US Project Facility for Rare Isotope Beams, FRIB Funded by DOE Office of Science 2020 completion Key Feature is 400kW beam power (5 x U/s) Separation of isotopes in-flight Fast development time for any isotope Suited for all elements and short half-lives Sherrill HUGS Lecture 1, Slide 30

31 Major Canadian Facility TRIUMF ISAC and ARIEL projectile target Isotope Separation On-Line ISOL Highest power ISOL facility - >50 kw 5 ma, 25 MeV, electrons Programs in nuclei, astrophysics, symmetry tests, condensed matter, medical isotopes 100 µa, 500 MeV, p Sherrill HUGS Lecture 1, Slide 31

32 Rare Isotope Production Methods Sherrill HUGS Lecture 1, Slide 32

33 Worldwide Growth of Rare Isotope Beam Facilities Sherrill HUGS Lecture 1, Slide 33

34 How many isotopes might exist? Estimated Possible: Erler, Birge, Kortelainen, Nazarewicz, Olsen, Stoitsov, Nature 486, (28 June 2012), based on a study of EDF models Known defined as isotopes with at least one excited state known (1900 isotopes from NNDC database) Represents what is possible now Sherrill HUGS Lecture 1, Slide 34

The Number of Isotopes Available for Study at FRIB (next generation facilities) Estimated Possible: Erler, Birge, Kortelainen, Nazarewicz, Olsen, Stoitsov, Nature 486, 509 512 (28 June 2012), based

35 The Number of Isotopes Available for Study at FRIB (next generation facilities) Estimated Possible: Erler, Birge, Kortelainen, Nazarewicz, Olsen, Stoitsov, Nature 486, (28 June 2012), based on a study of EDF models Known defined as isotopes with at least one excited state known (1900 isotopes from NNDC database) For Z<90 FRIB is predicted to make > 80% of all possible isotopes Sherrill HUGS Lecture 1, Slide 35

36 Uncertainty in Estimates Estimated Possible: Erler, et al. to be published Sherrill HUGS Lecture 1, Slide 36

37 Open Questions in the Search for the Limits Open Questions: How many elements can exist? We are up to element 118 and counting. Are there long-lived superheavy elements, with half lives of greater than 1 year? Where are the atoms of the various elements formed in nature? What makes atomic nuclei stable? We know Strong and Electroweak forces are involved, but don t understand how in detail. The inability to answer this question is reflected in our inability to answer the first three questions. Sherrill HUGS Lecture 1, Slide 37

38 References History of nuclear physics - E. Segre, From X-Rays to Quarks, W.A. Freeman & Co, San Francisco, 1980 Heavy element searches - Heaviest nuclei from Ca-48-induced reactions, Yu. Oganessian, J. Phys. G 34(2007) R165-R242. Isotope searches - Rare isotope science Geesaman, Gelbke, Janssens, Sherrill, Annu. Rev. Nucl. Part. Sci :53 92 Rare isotope production Geissel, Munzenberg, Riisager, Ann Rev. Nuclear and Part. Science Vol. 45 (1995) Sherrill HUGS Lecture 1, Slide 38

Ecole Internationale Joliot Curie: New Avenues with Radioactive Ion Beams Lecture 1

Ecole Internationale Joliot Curie: New Avenues with Radioactive Ion Beams Lecture 1 September, 2011 Bradley M. Sherrill FRIB Chief Scientist Brad Sherrill - Ecole Joliot Curie September 2011, Slide 1 Slid