The use of Traps in Modern Nuclear Physics CENTRE D'ETUDES NUCLEAIRES DE BORDEAUX GRADIGNAN

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1 The use of Traps in Modern Nuclear Physics Stéphane Grévy CENTRE D'ETUDES NUCLEAIRES DE BORDEAUX GRADIGNAN

2 The use of Traps in Modern Nuclear Physics Stéphane Grévy Directeur de Recherches CNRS : PhD at IPN Orsay Study of halo nuclei 11 Be and 11 Li : Post Doctoral position at the NSCL-MSU (US) Main scientific program : Study of the modifications of the shell structure in the n-rich nuclei Experimental program centered around N= and N= : LPC Caen Development of the neutron multi-detector array TONNERRE : GANIL Scientific coordinator of the LISE spectrometer -1 : CENBG Scientific coordinator of the PIPERADE project for DESIR/SPIRAL CENTRE D'ETUDES NUCLEAIRES DE BORDEAUX GRADIGNAN

3 The use of Traps in Modern Nuclear Physics Content - Why to trap particles? - What is trapping/cooling? - History - Main applications - How to trap particles? - Penning traps - Paul traps - cooling - Traps in the "real" life Some applications in nuclear Physics

4 Why to trap particles? The modern trappers : grown at the Heisenberg's school High precision implies very long observation time Ε t 1 confinement Trapping = isolation of particles over a long period of time For an atomic physicist Dream : single atom at rest in a free space, free of uncontrolled perturbation Long observation time: ion-motion manipulation; precision measurements ; almost a reality with traps Isolation: no matrix effects thermal isolation low temperature high control of transformations (reactions/decays) single species antiparticles experiments on few or ever a single ion

"infinite" storage time - single ion sensitivity - high accuracy - mass

5 Trapping and Storage devices storage ring Atom trap Penning and Paul trap relativistic particles particles at nearly rest in space - ion cooling - "infinite" storage time - single ion sensitivity - high accuracy - mass spectrometric capabilities large number of applications in atomic and nuclear physics

History Physics landscape at the dawn of the XX th century Composition of matter o Mechanical laws o Electromagnetism o Statistical thermodynamics Newton Maxwell Kelvin, Maxwell, Boltzman Gibbs

All that remains is more and more precise measurement William Thomson (Lord Kelvin), 19 British Association for the advancement of Science John Dalton o Matter is made of indivisible atoms o

7 History Physics landscape at the dawn of the XX th century Composition of matter o Mechanical laws o Electromagnetism o Statistical thermodynamics Newton Maxwell Kelvin, Maxwell, Boltzman Gibbs There is nothing new to be discovered in physics now. All that remains is more and more precise measurement William Thomson (Lord Kelvin), 19 British Association for the advancement of Science John Dalton o Matter is made of indivisible atoms o Atoms of a given element are identical o Atoms of an element can be combined to those of another one to create a chimical compound o Atoms of different elements have different masses Beginning of XX th century : Two simultaneous revolutions o Major discoveries observation of the radioactivity sub-atomic world o New concepts Quantum physics

History 194: Pauli proposed the idea of an inner degree of freedom of the electron, which he insisted should be thought of as genuinely quantum mechanical in nature 195: Uhlenbeck&Goudsmit postulate

8 History 194: Pauli proposed the idea of an inner degree of freedom of the electron, which he insisted should be thought of as genuinely quantum mechanical in nature 195: Uhlenbeck&Goudsmit postulate existence of spin and magnetic moment g of the e - 197: equation of Dirac theoretical justification of the spin and g= 197 intense discussions (Dirac, Bohr, Pauli ) about the best experiment to measure the 193 magnetic moment of a free electron 193: Solvay Conference "Bohr's theorem" : forbidden tu use "classical" magnetic moment experiments to measure the g-parameter of the free electron Zeemann Dirac Curie Einstein Langevin Debye Pauli Bohr Heisenberg Very interesting period of sciences history. Difficulty to apply the new quantum physics; intellectual "blockage"; problems of "language"

9 History 1947: First experiment of Nafe, Neson and Rabi on the hyperfine structure of the ground state of H and D atoms difference with theory of.% Breit : because of g Other experiments g = (1.119±.5) g/g ~ The uncertainties are coming from relativistic corrections and the interactions between the valence electrons and the other ones in the atom 1948 Better experiments but still on bound electrons in the atom 1957 At the limit because the relativistic corrections ~ needed precision Need for new type of experiments on unbound electrons Idea to trap the electrons but Impossible to create a 3D trapping potential using only electrostatic fields Penning and Paul traps

10 Birth of the Penning trap 1936 : F. M. Penning built a vaccum gauge based on a discharge tube in a magnetic field B CATHODE HIGH VOLTAGE ANODE CATHODE AMMETER -HV between Anode and grounded Cathodes -Discharges in the gas production of electrons - Ionization of the gas Low current IDEA : use a magnetic field to force the electrons to describe tight cyclotron orbits around the magnetic field lines slowing the diffusion rate more ionization more current Possibility to measure lower pressures 1949 : Pierce explicit description of a harmonic electron trap - electric field : pure quadrupolar (hyperbolic electrodes) - magnetic field "Penning-Pierce" trap design 1959 : Dehmeltfirst high vaccum magnetron trap trapping time ~1 sec

11 Birth of the Paul trap 1951 : W. Paul works on the use of multipoles to focus molecular beams - Beam along the z axis - Passage through quadrupoles : If beam focused along x defocused along y But if regular sequence of alternatively converging and diverging lenses net convergence : "strong focussing principle" Idea to apply an oscillating field to focus in x and y direction using the same electrodes 1964 : First application of Paul trap : spectroscopy of Be ions

structures CHEMISTRY ION BEAM MANIPULATION cooling accumulation beam-bunching new accelerator concepts ultra-high mass

13 Main applications of Ion storage devices NUCLEAR PHYSICS nuclear binding energies laser spectroscopy decay spectroscopy ATOMIC PHYSICS MOLECULAR & CLUSTER PHYSICS laser + microwave spectroscopy Reactions, life-times PLASMA PHYSICS Ordered structures CHEMISTRY ION BEAM MANIPULATION cooling accumulation beam-bunching new accelerator concepts ultra-high mass separation TEST OF FUNDAMENTAL INTERACTIONS CVC parity violation CPT, QED METROLOGY kilogram fine structure constant frequency standards

14 How to trap particles? -Required : -Desired : potential minimum in 3 dimensions harmonic force in direction of the trap center - ideal oscillator - constant amplitude - evolution around a stable equilibrium - constant frequency during the time r F r = e. Φ Φ = Ax ² + By² + Cz² A, B, C > to have a minimum ² Φ ² Φ ² Φ - Laplace's equation : Φ = + + = x² y² z² - Simplification : rotational symmetry along the beam axis z x y z U U Φ = ( x² + y² z²) = ( ρ² z²) d d saddle point at the origin - minimum for one coordinate - maximum for one coordinate A+B+C= At least one constant < unstable in that coordinate trapping direction Φ ρ z escape direction

15 How to trap particles? - How to generate such a harmonic potential? Φ - we want equipotential surfaces : ρ² - z² = cst Hyperboloidal shape ρ z Φ = U ( ρ² z²) d - How to trap particles with such a harmonic potential?

16 Storage of ions in a Penning trap U U Φ = ( x² + y² z²) = ( ρ² z²) d d B Ion q/m Charge q Mass m U Ion the beam axis (ρ=), the particle oscillates with the axial frequency ω z : On the plane z=, the particle moves on a circular orbit with the cyclotron frequency ω c : ω z = qu md ω c = q m B

17 Storage of ions in a Penning trap Force : quadrupolar potential + Lorentz : Equation of motion : Axial direction : B=Bz r F r r F = qe( r) + qv r r = q Φ( r) + qv B = mr & r r B U ( ρ² z²) d force is purely electrostatic && z = ω qu z z harmonic oscillation in z ω = z md with qu > Radial direction : the x and y component of the force are combination of - a dominant restraining force due to B (characterized by ω c ) - a repulsive electrostatic force that tries to push the particles out of the trap Φ = coupled radial equations x ω && = z x ω y y ω & = z y + ω x c c substitution u = x + iy q ωc = B m u( t) = u e iωt ωz iωcu& u + u& = modified (by E) cyclotron frequency ω ω = + ω ω c c z + 1 ωc magnetron frequency ω ω ω = ω c c z 1 ωc

18 Movement of ions in a Penning trap axial motion E p E k B (x,y) ω c ω z ~ 1 khz magnetron motion ~E p ω - ω + ω z ω - ~ khz modified cyclotron motion z ω z ω + ~ 1MHz ~E K 3 independent motions at 3 eigenfrequencies The free cyclotron frequency is inverse proportional to the mass of the ions! ωc = qb / m ω c = ω + +ω - +ω z ω c = ω + + ω - Possibility to "manipulate" the ions - by increasing one of the motions (excitations) - by reducing one of the motions (cooling) - by transferring one motion to another one

19 Manipulation of ions in a Penning trap 1- Dipolar azimuthal excitation : either of the ion's radial motions can be excited by an electric dipole field in resonance with the motion frequency amplitude of the motion increases/decreases - Quadrupolar azimuthal excitation : if the two radial motions are excited at their sum frequency, they are coupled continuously converted into each other

20 Penning trap geometries Hyperbolical Penning trap Cylindrical Penning trap 5 1 mm 5 1 mm 5 1 mm V 8 4

21 Storage of ions in a Paul trap Rotating E field PAUL TRAP Escape axis Φ = U U ( x² + y² z²) = ( ρ² z²) d d U U +V cosωt

22 Paul trap geometries Hyperbolical Paul trap Linear Paul trap

23 Storage of ions in a Paul trap Force : radiofrequency quadrupolar potential Equation of motion : q( U q( U + V cosωt) ρ + && ρ = mρ + V cosωt) z + && z = mρ q Φ( r, t) = mr & r substitution Ω τ = t a u = x,y,z z q z = a = q r F = qe(r) r r 8qU = mr Ω 4qV = mr Ω Φ U + V cosωt = ( ρ² z²) d d u dτ + ( a q cos τ ) u u u Mathieu differential equation = exact solution - A, B: constants depend on the initial conditions - C n : Amplitudes of the Fourier components of the particle motion - ω u = β u Ω micro motion (fast) macro motion (slow)

trajectory 3D Paul Trap a q z z = a = q r r 8qU = mr Ω 4qV = mr Ω m/q : given by the physics r : dimension of the

24 Ion trajectory in a Paul trap and Stability qu u( t) 1 cosωt) cos( ) = ωut ρ -Stability depends on q and a values depends on : q/m, r, Ω, U and V Stability diagram ω u : macro motion (slow) Ω: micro motion (fast, RF) Ion trajectory 3D Paul Trap a q z z = a = q r r 8qU = mr Ω 4qV = mr Ω m/q : given by the physics r : dimension of the trap U, V : applied voltages Ω : applied frequency you are able to choose r, U, V O and Ω to have a stable solution for a given m/q

25 What is cooling? Cooling = enhancement of the phase space density of a beam i.e. simultaneous reduction of size and angular divergence (transverse momentum) i.e. reduction of its emittance A=π.ε= constant But : Liouville's theorem : "For a given energy (velocity), the emittance e (mm.mrad) -the product of size and angular divergence- must be constant if there are only conservative forces" Solution : cooling possible if external interaction is applied for ions : with electrons electron cooling with atoms buffer gas cooling with lasers laser cooling

trapping potentials) - the manipulation of

26 Why Cooling? Cooling is important for : - the beam preparation (e.g. by use of RFQ -RadioFrequency Quadrupole- Paul trap) to bunch the beam (ovoid losses) to inject properly the ions in a trap (small trapping potentials) - the manipulation of the ions in the trap (e.g. mass selective centering in Penning tarp) Increase : - accuracy - sensitivity - efficiency

27 Quadrupole Mass Analyzer linear Paul "trap" (no z trapping) m U, V and Ω m i > m m j < m

- (B atom + B nucleus )/c Nuclear physics is here n-n(-n) interaction δm/m

28 Why to measure (precisely) masses? = N + Z + Z binding energy M Atom = N m neutron + Z m proton + Z m electron - (B atom + B nucleus )/c Nuclear physics is here n-n(-n) interaction δm/m < 1-1 δm/m = Masses determine the atomic and nuclear binding energies reflect all forces in the atom/nucleus.

29 Why to measure (precisely) masses? δm/m General physics & chemistry 1-5 N + Z + Z binding energy Nuclear structure physics 1-6 Astrophysics - separation of isobars - separation of isomers 1-7 Weak interaction studies 1-8 Metrology - fundamental constants 1-9 Neutrino physics CPT tests 1-1 QED in highly-charged ions - separation of atomic states 1-11

30 Why to measure (precisely) masses? What does a relative uncertainty of 1-8 mean? weight (empty): 164 kg Or one (little) step walking around the Earth!

atom + B nucleus )/c Liquid Drop Model B = a v.a -a s.a /3 -a c.

Meitner and Frisch to explain the Fission in term of competition between Coulomb and Surface

31 Why to measure (precisely) masses? Nuclear physics is here n-n(-n) interaction M Atom = N m neutron + Z m proton + Z m electron - (B atom + B nucleus )/c Liquid Drop Model B = a v.a -a s.a /3 -a c.z(z-1)/a 1/3 -a sym (Z-N) +Δ Weizsäcker, Zeitschrift der Physik, 96, 431 (1935) Used in 1935 by Meitner and Frisch to explain the Fission in term of competition between Coulomb and Surface Comparison B nucl : Theory-experiment 1 MeV difference for masses of 1-1 GeV 1 - to 1-3 Nuclear structure effects like shell closures become visible. 1949: The shell model and magic numbers (Göppert-Mayer + Jensen).

32 Why to measure (precisely) masses? Cs (Z=55)

33 How to measure (precisely) masses? 1 and ) production of the ions of interest and first selection In-Flight Target Ions Electrons 1 In-Flight separator R=1-1 3 Ion catcher Fast beam experiments "Stopped" beam experiments ISOL Target Ion source Reaccelerator Reaccelerated beam experiments Ions Electrons "Stopped" beam experiments 1 On-line separator R=1-1 3 Reaccelerator Reaccelerated beam experiments

34 How to measure (precisely) masses? 3- beam preparation In the Penning trap : - timing cycles : [5 5]msec bunches - low trapping voltages : few Volts small energy dispersion i.e. small emittance ~1 µsec 5-5 msec radiofrequency quadrupole RFQ (Paul trap) GPIB : General Purpose Ion Buncher DESIR@SPIRAL

35 How to measure (precisely) masses? 3- beam preparation buffer gas 59,9kV 1 1 -ions E k =6keV; E k =1eV -potential barrier E k ~1eV 3 - elastic scattering thermalisation - RF potential radial confinement 6kV E k =6 kev 59.9kV E k =1 ev DC potential axial confinement DC potential bunching 6 -"cooled" ions E k =59.9keV; E k =1eV kv

36 How to measure (precisely) masses? 4- mass measurement preparation Penning trap Buffer-gas (He) in preparation trap Well-controlled conditions buffer-gas (He) contaminant ions Ions of interest

37 How to measure (precisely) masses? 4- mass measurement preparation Penning trap Dipolar excitation at magnetron frequency ( mass independent) Quadrupolar excitation at the cyclotron frequency mass selective recentering large bandwidth resolving power ~1 5 (to separate isobars) G. Savard et al.,, Phys. Lett. A 158 (1991) 47. Ejection of the ions through a diaphgram

38 How to measure (precisely) masses? 4- mass measurement measurement Penning trap Dipolar excitation at cyclotron frequency mass selective Larger radius short bandwidth resolving power ~1 7-8 (to measure the mass) In practice : -frequency scan around ω c - ejection of the nuclei - measurement of their time-of-flight When ω c = q m B nuclei at the larger radius Smaller TOF

at the larger radius orbital energy magnetic field gradient

39 How to measure (precisely) masses? 4- mass measurement measurement Penning trap In practice : - frequency scan around ω c - ejection of the nuclei - measurement of their time-of-flight When q ω c = B m nuclei at the larger radius orbital energy magnetic field gradient outside the PT converts any radial energy into axial energy axial energy higher velocity smaller TOF

40 How to measure (precisely) masses? 4- mass measurement measurement Penning trap Mean TOF [µs] Cs measurement trap m/ m = 86, ω c Excitation Frequency [Hz] ω c excitation time 1.s FWHM =.95 Hz TOF Eff. = 1% - Each point corresponds to an excitation at a given frequency - Minimum TOF ω c q - ω c = B m need to know B with the same precision - in practice, unknown masses are always measured relative to known reference(s) ω ω c, ref c, unknown -resolving power : R = m m - For each point, the nucleus is excited during a time T exc 1 - ωc = T m = m exc unknown ref m m higher precision = longer excitation time e e m ~ m unknown ref ωc = ω c

42 (us) mean TOF ( Questions!? f exc (Hz) 1) What are these two resonances observed when measuring the mass of 68 Cu? the ground state and an isomeric state ) Which one is the ground and the isomeric state? Why? ground state = lowest mass higher frequency 3) What is the observed resolving power? R=w/ w=133894/5~ ~54 kev 4) What was the excitation T exc time to get this line width? w=5hz Texc~msec 5) The reference ions was 85 Rb with mass m 85,Rb = 84, (14) u. The measured frequency ratio was,8818() for 68g Cu,89879(19) for 68m Cu. Calculate for both states the mass excess in kev (ME = (m A)u ; 1u= MeV) m( 68 Cu gs ) = R*m( 85 Rb) = u ME_gs= MeV m( 68 Cu iso ) = R*m( 85 Rb) = u ME_iso= MeV 6) What is the excitation energy of the isomeric state? E exc = ME_iso-ME_gs=717 kev

44 How to measure (precisely) masses? The TOF-ICR technique is very powerfull but. it is a destructive method! to detect a ion, you have to extract it from the trap. ion signal mass/frequency spectrum Amplitude induced image current read through tuned tank circuit very small signal ~fa FT-ICR Fourier-Transform- Ion Cyclotron Resonance Advantage : need only one ion to measure a mass whereas ~3 are needed with the classical TOF-ICR technique But: very small signal noise delicate electronics with very high Q factor (use of cryogenic technics )

45 Multi-reflection time-of-flight and Penning-trap mass spectrometry 51,5 Ca F. Wienholtz et al., Nature 498, 346 (13) ISOLTRAP (CERN), TITAN (TRIUMF) B 53,54 Ca R. Wolf et al., Int. J. Mass Spec. 349, 13 (13) T. Dickel et al., Nucl. Instrum. Meth. B 317, 779 (13)

46 MR-TOF-MS - few words Dedicated poster P. Chauveau i- Principle Time-of-Flight separation in a linear trap Nuclei extrated with the same energy M v 13 Sn : mass = v =.9486 cm/ns 13 Sb : mass = v = kev In 1 msec - Flight pass : km! - _L : cm - _TOF : 1 ns multi reflections (~4) in a "linear trap" Beam purifier Mass analyzer

47 MR-TOF-MS - few words ii- Developments Energy spread need "time focussing" ToF foc cussing Ions extracted from RFQ have (small) energy and position distributions T RFQ time focussed plane Need: Nuclei with higher energy to have longer revolution time adjustment of the slope of the mirrorvoltage time focussed plane E E+δE Wolf et al., IJMS 31 13, 8 (1) time focussed plane "optimized" resolution power Generalization: Mirrors optimization to have a Flight time independant from : energy transverse position divergence

48 Multi-reflection time-of-flight and Penning-trap mass spectrometry 51,5 Ca ISOLTRAP (CERN), TITAN (TRIUMF) B 53,54 Ca R. Wolf et al., Int. J. Mass Spec. 349, 13 (13) T. Dickel et al., Nucl. Instrum. Meth. B 317, 779 (13) extrapolation

49 Mass measurements around N= Ca p3/ f7/ π ν d3/ s1/ d5/ - change in the slope of the S n is an indication of a shell closure (or more generally, a change in the shell structure) observed at N= and N=8 in Ca isotopes

50 Multi-reflection time-of-flight and Penning-trap mass spectrometry 51,5 Ca B Production rates of ~1 ions/s Massmeasurementsvia S n establish new magic number at N = 3 Correct prediction from 3N-forces (A. Schwenk et al., TUD) F. Wienholtz et al., Nature 498, 346 (13) ISOLTRAP (CERN), TITAN (TRIUMF) 53,54 Ca R. Wolf et al., Int. J. Mass Spec. 349, 13 (13) T. Dickel et al., Nucl. Instrum. Meth. B 317, 779 (13) Z= Ca N= 8 magic number N= 3 magicnumber

Purification of ISOL type RIB ISOL Target Ion source Ions Electrons On-line separator Stopped beam experiments -High Resolution Magnetic Separators (HRS) - HRS @ ISOLDE - CARIBU @ TRIUMF Resolving

51 Purification of ISOL type RIB ISOL Target Ion source Ions Electrons On-line separator Stopped beam experiments -High Resolution Magnetic Separators (HRS) - ISOLDE - TRIUMF Resolving power R= M/M ~ 1 not enough to separate all the isobars 1 4 limit 1 5 limit Resolving power R = M/ M New idea : use a double Penning trap to purify large bunches of exotic nuclei to obtain totally pure samples and perform precision measurements PIPERADE project for DESIR/SPIRAL

52 Test of the fundamental interactions dedicated poster C. Magron Standard model contains all les rules concerning the reactions between quarks and/or leptons, interacting through the electroweak interaction and/or quantum chromodynamics depends of a finite number of parameters fixed by experiments Weak interaction responsible of the beta-decay : V-A theory, based on experimental observations transition strenght: f(z,wo)t = g Vector MFermi + + Fermi transitions K f(z,wo)t = no axial current (selection rules) g = f(q ec ) * T 1/ / BR Vector M K Fermi p n + Ft + + γ BR + T 1/ g Axial MGamow Teller Q EC CVC hypothesis (Vector Curent Conservation) g Vector is identical for all β-transitions ft = constante Cabibbo-Kobayashi-Maskawa u' s' = d' V ud V us V ub V cd V cs V cb V td V ts V tb quarks are eigenstates of the strong interaction, not of the weak interaction Unitarity of CKM matrix : V ud ² + V us ² + V ub ² = 1 u d + relation between V ud and ft for the Fermi transitions : V ud ² = u s d π 3 ln g µ ².ft. M if ²

: Ft = (37.8 ±.79) s for 13 transitions 1.3 * 1-4 Ft = 37.8(79) s V ud =.9745() V ui =.

53 Test of the fundamental interactions Study of the + + Fermi transitions Verification of the CVC hypothesis by comparing ft for different nuclei Extraction of V ud Verification of the unitarity of the CKM matrix Needed precisions overall precision : Ft = (37.8 ±.79) s for 13 transitions 1.3 * 1-4 Ft = 37.8(79) s V ud =.9745() V ui =.99995(61) individualmesurements < 1-3 f: f(q EC ) Q < * 1-8 < 1keV T 1/ : T << 1-3 BR: BR < 1-3 Q EC Study on exotic nuclei of very high purity Ft γ + + BR T 1/

54 Test of the fundamental interactions JYFLTRAP z r Q EC = ( ±.54) kev T. Eronenet al., 6 T 1/ = (116.1 ±.15) ms G. Canchel et al., 5

55 Purification of ISOL type RIB dedicated poster M. Aouadi DESIR-SPIRAL Goals: Very high Resolving power (> 1 5 ) to clean isobars not cleaned by the HRS + isomers Penning traps can reach a resolution (up to 1 8 ) but are limited in terms of number of ions Purifying very large samples (accept 1 5 to 1 6 per bunch1 7 to 1 8 pps) Increasing the number of ions makes the re-centering inefficient Additional potential created by the cloud itself frequency-shifts peak broadening screening effects 1 3 ions 1 4 ions 9% 136 Te, 1% 136 Sb P = 1-4 mbar B = 7T r = mm SIMBUCA code, S. Van Gorp et al., NIM A 638, 19 (11)

56 Purification of ISOL type RIB DESIR-SPIRAL Solutions Purification trap r = 3 mm Large inner radius (3 mm) and length (~1 cm) Decrease the cloud density Limit space charge effects 1 4 ions r = mm ions r = 3 mm 9% 136 Te, 1% 136 Sb P = 1-4 mbar B = 7T

Purification of ISOL type RIB PIPERADE @ DESIR-SPIRAL Solutions Purification trap r = 3 mm Large inner radius (3 mm) and length Decrease the cloud density Limit space charge effects

57 Purification of ISOL type RIB DESIR-SPIRAL Solutions Purification trap r = 3 mm Large inner radius (3 mm) and length Decrease the cloud density Limit space charge effects Broad-band FT-ICR detection Identify online abundant contaminants FT-ICR : Fourier Transform Ion Cyclotron Resonance x I f A y Ring-Pickup-Electrodes ion current signal t mass spectrum f

Purification of ISOL type RIB PIPERADE @ DESIR-SPIRAL If you know the

Alternative techniques Simulations (MPIK and CENBG) and tests are ongoing to

rotating wall, ) 9% 136 Te, 1% 136 Sb P = 1-4 mbar B = 7T With a

58 Purification of ISOL type RIB DESIR-SPIRAL If you know the frequency of the most abundant contaminant (thanks to the FT-ICR) Alternative techniques Simulations (MPIK and CENBG) and tests are ongoing to find new separation methods (phase splitting, SIMCO, axial coupling, rotating wall, ) 9% 136 Te, 1% 136 Sb P = 1-4 mbar B = 7T With a pre-excitation at ν+ of contaminant Time(ms) P. Ascher, S. Naimi, A. de Roub bin, E. Minaya - MPIK, P. Dupré CSNSM

Purification of ISOL type RIB PIPERADE @ DESIR-SPIRAL Febiad Ion source : - emittance caracterized RFQ-GPIB "General Purpose Ion Buncher" - on test

59 Purification of ISOL type RIB DESIR-SPIRAL Febiad Ion source : - emittance caracterized RFQ-GPIB "General Purpose Ion Buncher" - on test Penning Trap - simulations underway - mechanical design ready - construction end of 15 - magnet ordered (delivery expected 6/16) - tests@cenbg in 16/17

60 Why Beta-Delayed Neutron Spectroscopy? For the most neutron-rich nuclei : - large Qβ - small Sn β-delayed neutron emission Experimental data are needed for : - astrophysics : r process nucleosynthesis of elements heavier than Fe - nuclear structure : properties of neutron rich nuclei - nuclei at the drip line - nuclei at the closed shell - - nuclear energy : reactor design, performance and safety - delayed neutron fraction Pn - average energy!! energy spectra needed accuracy 1-5 % < % but neutrons are always difficult to measure.

61 Detection of Neutrons Sub-atomic particles have to interact with their environment to be "detected" ionization But neutrons are neutral no Coulomb interaction always an "indirect measurement" - low energy capture n+ 3 He 3 H+ 1 H activation 56 Fe(n,p) 56 Mn -high energy (in)elastic scattering recoiling particles : p Compromises to do on : - efficiency - resolution - threshold Is it possible to performed beta-delayed neutron spectroscopy without detecting the neutrons??

62 Beta Delayed Neutron Spectroscopy without detecting neutrons Principle : By momentum and energy conservation : TOF of recoiling A-1 (Z+1) neutron energy - trap the nuclei as ions - cool by He gas to ~1mm 3 volume - ions decay at rest at the trap center - β only : slow recoil - βn : fast recoil - trigger on β's seen by plastic - Measure recoil TOF to MCP HI recoil HI recoil Q β /E n after β-decay after n-emission Mass MeV (E / TOF 5cm) (E / TOF 5cm) 45 1 < 1.3 kev 17 kev > 67 ns 5 ns 5 < 36 ev 18 kev > 1.3 µs 73 ns < 7 ev 43 kev >.8 µs 116 ns Plastic E-E A (Z) β A (Z+1) * + β - + ν MCP A (Z+1) (Z) A-1 (Z+1) + n A-1 (Z+1) n HP Ge γ ν Ge HP This is possible because nuclei are trapped in a free environment no "matrix" effects

Beta Delayed Neutron Spectroscopy without detecting neutrons Advantages: no need to detect neutons -

~3keV - Gaussian detector response - almost background free - no need for γ/n discrimination A Z A (Z+1)

Plasti ic E-E β n γ ν HP Ge ε total (β&n) : ~15%@1 MeV resolution : ~1% n-threshold : ~3 kev problematic

63 Beta Delayed Neutron Spectroscopy without detecting neutrons Advantages: no need to detect neutons - total efficiency (β-recoil) : up to 5% - energy resolution (FWHM) : ~3% - neutron energy threshold : ~3keV - Gaussian detector response - almost background free - no need for γ/n discrimination A Z A (Z+1) * + β - + ν A-1 (Z+1) + n MCP A-1 (Z+1) Plastic scintilla ators Liquid scintilla ators MONSTER modules Plasti ic E-E β n γ ν HP Ge ε total (β&n) : ~15%@1 MeV resolution : ~1% n-threshold : ~3 kev problematic line shapes ε total (β&n) : ~5%@1 MeV resolution : ~5% n-threshold : ~1 kev HP Ge Seems to be a good idea Is it feasible?

64 Proof of principle 5 Cf Gaz source Catcher RFQ HRS 137 I Linear Paul Trap present setup dedicated setup - total efficiency :.5 % 5% - energy resolution ~ 1 % 3% - n threshold kev 5 kev

65 The use of Traps in Modern Nuclear Physics Thanks for your attention Thanks to the organizers Thanks to K. Blaum, D. Lunney and the PIPERADE team for materials

Precision Nuclear Mass Measurements Matthew Redshaw Exotic Beam Summer School, Florida State University Aug 7 th 2015

Precision Nuclear Mass Measurements Matthew Redshaw Exotic Beam Summer School, Florida State University Aug 7 th 2015 Outline WHAT are we measuring? - Nuclear/atomic masses WHY do we need/want to measure