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HISPEC: H i-resolution I n-beam SPEC troscopy at FAIR:

Overview. HISPEC: H i-resolution I n-beam SPEC troscopy at FAIR: Exploring the Limits of Nuclear Existence . What is HISPEC? Fragmentation Reactions and in-beam spectroscopy? Experimental Method – what do we need? HISPEC at FAIR and the UK

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HISPEC: H i-resolution I n-beam SPEC troscopy at FAIR:

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  1. Overview HISPEC: Hi-resolution In-beam SPECtroscopy at FAIR: Exploring the Limits of Nuclear Existence • What is HISPEC? • Fragmentation Reactions and in-beam spectroscopy? • Experimental Method – what do we need? • HISPEC at FAIR and the UK • Some personal scientific highlights! Surrey Minischool - June 09 - Bentley

  2. What is Nuclear Physics / Nuclear Structure for? Towards a predictive (and unified) description of nuclei Surrey Minischool - June 09 - Bentley

  3. Experiment-led.... Surrey Minischool - June 09 - Bentley

  4. Need access to exotic nuclei – radioactive beams... • Stable beam + Stable target: • Fusion-Evaporation • Compound Nucleus near stability Surrey Minischool - June 09 - Bentley

  5. Radioactive beams...two methods Surrey Minischool - June 09 - Bentley

  6. Radioactive beams...the FRAGMENTATION method Secondary target (Reaction of Interest) Primary target e.g.9Be or 12C Exotic Fragment ~100 MeV/u Primary (Stable) Beam ~ 104 pps >109pps, ~ 10’s GeV Gamma-ray Detector Array around target... FRAGMENT SEPARATOR Fragment Identification Surrey Minischool - June 09 - Bentley

  7. The secondary reaction... Prefragment Equilibrated nucleus Relativistic Coulomb excitation / fragmentation 112Sn →Au Coulomb interaction excited nucleus FIDIPRO-EFES - Bentley

  8. Fragmentation Example: Proton Rich 53Ni... 1011 pps 58Ni, 150 MeV/u 600 mg/cm2 Be target 0.5 -1.0 × 106 pps (70% 56Ni) 188 mg/cm2 Be S800 Spectrograph Few 105 pps 56Ni, 75 MeV/u NSCL Experiment #5117, March 2007 – Bentley et al Surrey Minischool - June 09 - Bentley

  9. Fragmentation Example: Proton Rich 53Ni... J.R. Brown et al. (YORK) in prep (2008) S800 – Fragment ID Drip line Z A/Z Surrey Minischool - June 09 - Bentley

  10. A=53 T=3/2 analogue states Z N=Z 53Mn – 3p removal N 53Ni – 3n removal First gamma-rays from N=Z-3 system above 33Ar. Surrey Minischool - June 09 - Bentley

  11. A=49 T=3/2 analogue states 49V – 5p,2n removal 49Fe – 2p,5n removal ? Surrey Minischool - June 09 - Bentley

  12. A=49 T=3/2 analogue states 49V 49Fe Z N=Z N Examine breakdown of isospin (proton-neutron) symmetry – see later Surrey Minischool - June 09 - Bentley

  13. FAIR: A European Fragmentation Facility Project launched on November 7, 2007 Surrey Minischool - June 09 - Bentley

  14. Super FRS – Provider of Exotic Beams... Low-Energy Branch Super-FRS Primary target to rings Surrey Minischool - June 09 - Bentley

  15. AGATA – The world’s best gamma-ray detector... AGATA(Design and characteristics) 4-array for Nuclear Physics Experiments at European accelerators providing radioactive and high-intensity stable beams • 180 large volume 36-fold segmented Ge crystals in 60 triple-clusters • Digital electronics and sophisticated Pulse Shape Analysis algorithms allow • Operation of Ge detectors in position sensitive mode  -ray tracking Surrey Minischool - June 09 - Bentley

  16. Issues with relativistic beams Doppler effects at v/c ~ 50% - TOUGH SPECTROSCOPY Doppler shift Doppler broadening Surrey Minischool - June 09 - Bentley

  17. AGATA – Tracking of Gamma-rays – a NEW technology... Large Gamma Arrays based on Compton Suppressed Spectrometers Tracking Arrays based on Position Sensitive Ge Detectors EUROBALL GAMMASPHERE AGATA GRETA e~ 10 — 5 % ( Mg=1 —Mg=30) e~ 40 — 20 % ( Mg=1 —Mg=30) Surrey Minischool - June 09 - Bentley

  18. AGATA – Tracking of Gamma-rays – a NEW technology... 4 1 Reconstruction of tracks e.g. by evaluation ofpermutations of interaction points Identified interaction points Highly segmented HPGe detectors (x,y,z,E,t)i g · · Pulse Shape Analysisto decomposerecorded waves · · 2 3 Digital electronics to record and process segment signals reconstructed g-rays Surrey Minischool - June 09 - Bentley

  19. Exotic Fragments at FAIR The Lund-York-Cologne Calorimeter (LYCCA) – Identification of the Exotic Fragments FAIR Target AGATA Flight path <4m HISPEC Fragment detectors Surrey Minischool - June 09 - Bentley

  20. Lund-York-Cologne CAlorimeter (LYCCA) 1. Target (Be, Au..), position (DSSD) and time start (CVD diamond) 2. Light CP array (position, energy loss, energy) – prompt p, alpha decay 3. Main array (~26 LYCCA modules) – ~3.5-4.0 m downstream from target 4. Possible configuration of LYCCA modules at the focal plane of a spectrometer – add A/Q to measurement of position, ToF, energy loss, E etc. Surrey Minischool - June 09 - Bentley

  21. Isotope ID from Energy (Loss) – (RISING DATA 2003, GSI) Particle ID: Z – from energy loss in DSSSD YES!! A – from total energy NO!! Simulation 47V : σ ~ 19 mb48V : σ ~ 20 mb 49V : σ ~ 9 mb 52Fe : σ ~ 30 mb 53Fe : σ ~ 50 mb Surrey Minischool - June 09 - Bentley

  22. LYCCA – Energy, Position and Time of Flight A LYCCA module (LUND) CsI Total E Si DSSSD (position and E) Fast Plastic (Lund) time-of-flight stop CVD diamond (York/Surrey) – time of flight stop The LYCCA-0 Prototype Target and CVD Diamond (ToF start) Surrey Minischool - June 09 - Bentley

  23. LYCCA – prototype simulation 2m 3m Titanium fragments - simulations Surrey Minischool - June 09 - Bentley

  24. LYCCA@HISPEC Identify Fragments through ENERGY, ENERGY LOSS and TIME-OF-FLIGHT Key UK Role: High timing resolution TIME-OF-FLIGHT array Surrey Minischool - June 09 - Bentley

  25. LYCCA@HISPEC DETECTOR of CHOICE = DIAMOND! CVD Polycrystalline Diamond Project (York, Surrey, GSI, Diamond Detectors Ltd) • Diamond Pros: • Good timing resolution measured with Rel. H.I I. ~ 50-60 ps FWHM • Radiation Hard (106 pps easy) • Diamond Cons: • NO company makes fabricated diamond detectors • Such large-areas not been tested • VERY expensive Surrey Minischool - June 09 - Bentley

  26. LYCCA@HISPEC 0.3m Time-of-flight “stop” 0.4m Reaction Target UK will design and construct the “Diamond Wall” Time-of-flight “start” Surrey Minischool - June 09 - Bentley

  27. Science with HISPEC – some personal highlights How does our understanding of fundamental nuclear properties evolve as we move towards the extremes of nuclear existence? • Ordering of quantum levels: shell effects far from stability (spectroscopy of neutron rich nuclear matter) • 100Sn: One of the holy grails (spectroscopy at N=Z) • Isospin (n-p) symmetry and its breakdown: beyond the Coulomb force (spectroscopy of proton rich nuclear matter) Surrey Minischool - June 09 - Bentley

  28. Nuclear Shells – cornerstone of understanding? The Nuclear Landscape Feature 1: Shell Effects Surrey Minischool - June 09 - Bentley

  29. Nuclear Shells – cornerstone of understanding? Systematics of Ground-state Deformation Surrey Minischool - June 09 - Bentley

  30. How good are Nuclear Models – how well are we doing? Mass model predictions of nuclear masses for the Cs isotopes No problems where we have known masses (stars) but the various theoretical prescriptions diverge as soon as we move to unknown masses. Surrey Minischool - June 09 - Bentley

  31. Why Exotic Nuclei – Magic Numbers in Danger....? ‘neutron rich’ ‘normal’ Wood-Saxon + spin-orbit diffuse surface + spin-orbit Nuclear potential How does the ordering of quantum states alter? How does the ordering of quantum states alter? Surrey Minischool - June 09 - Bentley

  32. Why Exotic Nuclei – Magic Numbers in Danger....? Standard magic numbers: 2, 8, 20 New magic number: 16 20 Surrey Minischool - June 09 - Bentley

  33. 100Sn? Surrey Minischool - June 09 - Bentley

  34. 100Sn? • Very close to drip line • Heaviest N=Z doubly magic nucleus – n-p degree of freedom? • Sn is Longest chain of semi- magic nuclei known • Evolution depends on single-particle and collective effects • Unique correlations possible between n & p spin-orbit partners • Core polarisation effects of neutrons and protons? HISPEC: B(E2) of 0+→2+100Sn can be done Surrey Minischool - June 09 - Bentley

  35. Why Exotic Nuclei? The Nuclear Landscape: Neutron-Proton Symmetry Surrey Minischool - June 09 - Bentley

  36. Neutron-Proton Symmetry MeV MeV MeV 4+ 8 8 8 8 8 8 3+ 2+ 3- 4+ MeV 2+ 0+ 4+ 4+ 3+ 3+ 2+ 2+ Surrey Minischool - June 09 - Bentley

  37. Coulomb Energy Differences (differences of excitation energies) Z Mirror Energy Differences (MED) N=Z N Tests the charge symmetry of the interaction Triplet Energy Differences (TED) Tests the charge independence of the interaction MED and TED are of the order of 10’s of keV Surrey Minischool - June 09 - Bentley

  38. Why Exotic Nuclei? – ISOSPIN Symmetry Z N=Z N Warner, Bentley, Van Isacker, NATURE Phys 2 (2006) 311. Surrey Minischool - June 09 - Bentley

  39. Why Exotic Nuclei? – ISOSPIN Symmetry What are the symmetry-breaking effects? Where in the nuclear landscape does the symmetry break down? Surrey Minischool - June 09 - Bentley

  40. Future research at HISPEC.... Spectroscopy at or beyond the proton dripline.... • What effects break the proton-neutron symmetry? • Spectroscopy of proton-unbound structures • Pairing between protons and neutrons • Testing predictions of isospin formalism Surrey Minischool - June 09 - Bentley

  41. A=53 T=3/2 analogue states Z N=Z 53Mn – 3p removal N 53Ni – 3n removal First gamma-rays from Tz= -3/2 system above 33Ar. Surrey Minischool - June 09 - Bentley

  42. Charge-Symmetry Breaking? Question: Origin of this effect – where else does it appear? 53Mn = full shell model calculation (with CSB) = shell model calculations without CSB J=2 effect 53Ni  J.Brown et al, submitted to PRC (R) 2009 Surrey Minischool - June 09 - Bentley

  43. 54Ni : At the limits of proton binding.... 98% 2% 95(1)% 5(1)% 28262628 D.Rudolph et al, Phys. Rev. C78 (Rap. Comm.) 2008 021301 PRL 97 (2006) 152501 Surrey Minischool - June 09 - Bentley

  44. The Formalism of Isospin... (yuch) E1 • What is expected? Tz -dependence of transition matrix element (hence decay probabilities) between isobaric analogue states? • ASSUME: • Charge-symmetry and charge independence • No isospin mixing • Wigner-Eckart theorem extracts Tz-dependence (DT=0) • Rule 1: E1s identical in mirror nuclei • ISOSPIN MIXING: • TT+1 and T+1T components can break the rule..... • Rule 2: E2s: B(E2)  Tz • ISOSPIN MIXING: • TT+1 and T+1T components can break the rule..... Not tested – at least not systematically and accurately ! Surrey Minischool - June 09 - Bentley

  45. Lifetimes at relativistic energies.... E~70 MeV/u E’~60 MeV/u E”~44 MeV/u 12C 500 mm D 114Pd To particle identification b=0.354 b”=0.28 b’=0.342 Eg” Eg’ 93Nb 100 mm to the g-ray detector Differential Plunger Techniquee.g.114Pd with Coulomb excitation • Incoming cocktail beam: …..116Ag , 15% 114Pd ( ~ 1500pps), 112Rh…… Surrey Minischool - June 09 - Bentley

  46. Differential Plunger.... target/ degrader diameter: 4 cm target/ degrader separation: 0 - 2,5 cm precision : ~ 1 μm target/ degrader thickness: ~1μm -1mm Surrey Minischool - June 09 - Bentley

  47. Differential Plunger.... 114Pd: τ =118 (20) ps 110Pd: τ=67 (8) ps • Dewald et al. • submitted to PRC/Rapid Surrey Minischool - June 09 - Bentley

  48. Isospin Symmetry in T=1 triplets, A~70 Z N=Z Difference in excitation energy EA* - EB* A B Analysis from B S Nara Singh et al, PRC 75 061301(R) 2007 N Surrey Minischool - June 09 - Bentley

  49. Isospin Symmetry in T=1 triplets, A~70 Neutron-proton pairing effects ? Odd-odd nucleus dominated by T=1 np-pairs, hence fewer T=1 pp pairs... (see LenziPRC 60 (2001)021303) Surrey Minischool - June 09 - Bentley

  50. Isospin Symmetry in T=1 triplets, A~70 Neutron-proton pairing effects ? If β2 changes from -0.3 to 0.35, CED ~ -7keV Shape-changing effects ? R. Sahu et al, JPG 13, 603 (1987) Def Shell model calcs → Stretch in β2 from 0.18 to 0.33 CED ~ -75 keV Surrey Minischool - June 09 - Bentley

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