TRIUMF Summer Institute, 2015 Precision Measurements of Nuclear - PowerPoint PPT Presentation

TRIUMF Summer Institute, 2015 “Precision Measurements of Nuclear Masses – Part 2” Klaus Blaum 113 th -25 th July 2015 Klaus.blaum@mpi-hd.mpg.de

Lecture 2 What did we learn? 1) Motivation for precision mass data 2) Liquid drop model and nuclear binding energy 3) Production of radioactive ions 4) Storage of charged particles 5) Penning trap technique What comes today? 1) Manipulation of stored ions 2) Frequency measurement techniques 3) Experimental setup 4) Applications of precision nuclear mass data * Nuclear physics and astrophysics

Storage of ions in a Penning trap B U Ion q/m Charge q Mass m ω = The free cyclotron frequency is inverse / qB m c proportional to the mass of the ions! An invariance theorem ω c = ω + + ω - ω c 2 = ω + 2 + ω - 2 + ω z 2 saves the day: L.S. Brown, G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986). K. Blaum, Phys. Rep. 425, 1 (2006).

Ion preparation and cooling Buffer-gas (He) in preparation trap buffer-gas (He) Motional amplitudes are reduced contaminent ions Ions of interest Well-controlled conditions Ion beam cocktail: R=10 2 -10 3 (Selection by dipole magnets)

Mass selective buffer-gas cooling Resolving Power R=10 5 Cooled ions Dipolar excitation at magnetron frequency (≈ mass independent) Quadrupolar excitation at the cyclotron frequency (mass selective recentering) G. Savard et al. , Phys. Lett. A 158 (1991) 247.

Manipulation of ion motions Dipolar excitation Quadrupolar excitation

Destructive ion detection

Non-destructive ion detection ion signal mass/frequency spectrum Amplitude „FT-ICR“ very small signal ~fA F ourier- T ransform- I on C yclotron R esonance

TRIGA-SPEC: TRIGA-LASER + TRIGA-TRAP project start @ TRIGA: 01/08 start data taking: 05/09 E CR ion source Mass separator RFQ TRIGA-LASER W. Nörtershäuser T RIGA -T RAP Nucl. Instrum. Meth. A 594, 162 (2008)

Nuclear structure studies 4 Nuclear structure and astrophysics studies In collaboration with CERN, GSI, TU Darmstadt, Greifswald, Dresden, Paris.

Chart of nuclides and magic numbers H D T Ca

Investigation of nuclear halos characteristic properties of nuclear halos large matter radius weakly bound increased charge radius 11 Li 207 Pb 9 Li +2n ? 11 = r c 9 r c 375 keV 0 keV 3/2 - probing halo 11 Li neutron – nucleus interaction 9 Be 9 Be 7 Be 7 Be 8 Be 8 Be 10 Be 10 Be 11 Be 11 Be 11 Be 11 Be 11 Be m m f f 7 7 . . 7 7 12 Be 11 Be: Phys. Rev. Lett. 102, 062503 (2009) 12 Be: Phys. Rev. Lett. 108, 142501 (2012) „Size“ & structure studies of 11,12 Be COLLAPS (ISOLDE) TITAN (TRIUMF)

Ca masses pin down nuclear forces Multi-reflection time-of-flight and Penning-trap mass spectrometry 51,52 Ca 53,54 Ca B R. Wolf et al ., Int. J. Mass Spec. 349, 123 (2013) T. Dickel et al ., Nucl. Instrum. Meth. B 317, 779 (2013) N = 28 magic Production rates of ~10 ions/s number Mass measurements via S 2n PRL 114, 202501 (2015) establish new magic number N = 32 magic number at N = 32 Correct prediction from N =31,32 3N-forces (A. Schwenk et al ., TUD) TITAN Z =20 Ca F. Wienholtz et al ., Nature 498, 346 (2013) ISOLTRAP (CERN), TITAN (TRIUMF)

Direct Mapping of Nuclear Shell Effects E. Minaya Ramirez et al ., Science 337, 1207 (2012) ChemistryWorld: Tweaked weighing scales help map the island of stability Where is the predicted “island of stability“? 256 Lr with the lowest yield ever measured in a Penning trap (2 ions/ minute) SHIPTRAP (GSI)

Question 400 1) Which one is the ground and the isomeric 380 state? Why? 360 340 1 + 320 300 2) What is the observed reolving power? 6 - 280 260 390 3) What was the excitation T rf time to get mean TOF (us) 360 this line width? 330 300 4) The reference ions was 85 Rb with mass 1 + 270 m 85,Rb = 84,911789732(14) u. The measured 240 frequency ratio was 0,800000818(20) for 390 68g Cu and 0,800009879(19) for 68m Cu. 360 Calculate for both states the mass excess 330 in keV defined by D = m − A u. 300 6 - 270 5) What is the escitation energy of the 240 0 5 10 15 20 25 30 35 isomeric state? f exc - 1338940 (Hz)

Masses Nuclear astrophysics studies Why is iron so much abundant than heavier elements such as gold? Why are there heavy elements at all and how did they come into existence? CPT, CSRe, ESR, ISOLTRAP, JYFLTRAP, LEBIT, SHIPTRAP, TITAN

Mass spectrometry for nucleosynthesis Nuclear masses (binding energies) determine the paths of the processes. A. Arcones et al. Can be addressed at FAIR

Nuclides at the rp-process path ν p – process CSRe (IMP, Lanzhou) JYFLTRAP (IGISOL) C. Weber et al ., Phys. Rev. C 78, 054310 (2008) V.-V. Elomaa et al ., Phys. Rev. Lett. 102, 252501 (2009) E. Haettner et al., Phys. Rev. Lett. 106, 122501 (2011) F. Herfurth et al ., Eur. Phys. J. A, 47,75 (2011) X. Tu et al ., Phys. Rev. Lett. 106, 112501 (2011)

Nuclear astrophysics: Neutron star Composition of the outer crust of a neutron star ( T 1/2 ~ 200ms) δ m / m ~ 10 -8 (< 1 keV) R. Wolf et al ., Phys. Rev. Lett., 110, 041101 (2013)

Nuclear astrophysics: r-process Compare calculated abundance to observation Mismatch comes from: - n-star-merger conditions! - Nuclear physics input not correct.  Need nuclear physics experiments & theory for predictions! rapid neutron capture β-decay Z seed A. Arcones et al.,2012 N H. Schatz et al. (γ,n) photo- equilibrium favours MNRAS.426.1940 “ waiting point ” disintegration

End of Lecture 2 What did we learn? 1) Storage, manipulation, detection of stored ions 2) Frequency measurement techniques 3) Applications of precision nuclear mass data • Nuclear structure studies • Nuclear astrophysics studies What comes next? 1) Further applications of precision nuclear mass data • Test of fundamental symmetries • Neutrino physics applications 2) Future facilities