12/17/2015Surrey Minischool - June 09 - Bentley1 HISPEC: Hi-resolution In-beam SPECtroscopy at FAIR: Exploring the Limits of Nuclear ExistenceOverview 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!

Towards a predictive (and unified) description of nuclei What is Nuclear Physics / Nuclear Structure for? 12/17/2015 2Surrey Minischool - June 09 - Bentley

12/17/2015 Surrey Minischool - June 09 - Bentley3Experiment-led....

12/17/2015 Surrey Minischool - June 09 - Bentley4 Need access to exotic nuclei – radioactive beams... Stable beam + Stable target: Fusion-Evaporation Compound Nucleus near stability

Radioactive beams...two methods 12/17/2015 5Surrey Minischool - June 09 - Bentley

12/17/2015 Surrey Minischool - June 09 - Bentley6 Radioactive beams...the FRAGMENTATION method Gamma-ray Detector Array around target... Primary target e.g. 9 Be or 12 C Secondary target (Reaction of Interest) Primary (Stable) Beam >10 9 pps, ~ 10’s GeV Exotic Fragment ~100 MeV/u ~ 10 4 pps Fragment Identification FRAGMENT SEPARATOR

FIDIPRO-EFES - Bentley7 112 Sn →Au Relativistic Coulomb excitation / fragmentation excited nucleus Coulomb interaction Prefragment Equilibrated nucleus The secondary reaction... 12/17/2015

Surrey Minischool - June 09 - Bentley8 NSCL Experiment #5117, March 2007 – Bentley et al × 10 6 pps (70% 56 Ni) 188 mg/cm 2 Be pps 58 Ni, 150 MeV/u 600 mg/cm2 Be target S800 Spectrograph Fragmentation Example: Proton Rich 53 Ni... Few 10 5 pps 56 Ni, 75 MeV/u

12/17/2015 Surrey Minischool - June 09 - Bentley9 S800 – Fragment ID Z A/Z Drip line J.R. Brown et al. (YORK) in prep (2008) Fragmentation Example: Proton Rich 53 Ni...

12/17/ Surrey Minischool - June 09 - Bentley A=53 T=3/2 analogue states 53 Mn – 3p removal 53 Ni – 3n removal First gamma-rays from N=Z-3 system above 33 Ar. N=Z Z N

12/17/ Surrey Minischool - June 09 - Bentley A=49 T=3/2 analogue states 49 V – 5p,2n removal 49 Fe – 2p,5n removal ?

12/17/ Surrey Minischool - June 09 - Bentley 49 V 49 Fe Examine breakdown of isospin (proton-neutron) symmetry – see later N=Z Z N A=49 T=3/2 analogue states

12/17/2015 Surrey Minischool - June 09 - Bentley13 Project launched on November 7, 2007 FAIR: A European Fragmentation Facility

Super FRS – Provider of Exotic Beams... 12/17/ Surrey Minischool - June 09 - Bentley to rings Low-Energy Branch Super-FRS Primary target

12/17/2015 Surrey Minischool - June 09 - Bentley15 AGATA 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 AGATA – The world’s best gamma-ray detector...

Surrey Minischool - June 09 - Bentley16 Doppler shift Doppler broadening Issues with relativistic beams 12/17/2015 Doppler effects at v/c ~ 50% - TOUGH SPECTROSCOPY

Tracking Arrays based on Position Sensitive Ge Detectors Large Gamma Arrays based on Compton Suppressed Spectrometers   40 — 20 % ( M  =1 — M  =30)   10 — 5 % ( M  =1 — M  =30) GAMMASPHEREEUROBALLGRETAAGATA AGATA – Tracking of Gamma-rays – a NEW technology... 12/17/ Surrey Minischool - June 09 - Bentley

Pulse Shape Analysis to decompose recorded waves Highly segmented HPGe detectors · · · · Identified interaction points (x,y,z,E,t) i Reconstruction of tracks e.g. by evaluation of permutations of interaction points Digital electronics to record and process segment signals  reconstructed  -rays AGATA – Tracking of Gamma-rays – a NEW technology... 12/17/ Surrey Minischool - June 09 - Bentley

AGATA HISPEC FAIR Exotic Fragments at FAIR Target Fragment detectors Flight path <4m 12/17/2015 Surrey Minischool - June 09 - Bentley19 The Lund-York-Cologne Calorimeter (LYCCA) – Identification of the Exotic Fragments

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) – ~ 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. 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) – ~ 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. 12/17/201520Surrey Minischool - June 09 - Bentley

Particle ID: Z – from energy loss in DSSSDYES!! A – from total energy NO!! Isotope ID from Energy (Loss) – (RISING DATA 2003, GSI) 52 Fe : σ ~ 30 mb 53 Fe : σ ~ 50 mb 47 V : σ ~ 19 mb 48 V : σ ~ 20 mb 49 V : σ ~ 9 mb Simulation 12/17/201521Surrey Minischool - June 09 - Bentley

A LYCCA module (LUND) Si DSSSD (position and  E) CsI Total E The LYCCA-0 Prototype CVD diamond (York/Surrey) – time of flight stop Fast Plastic (Lund) time-of- flight stop Target and CVD Diamond (ToF start) LYCCA – Energy, Position and Time of Flight 12/17/201522Surrey Minischool - June 09 - Bentley

A σ (mb) LYCCA – prototype simulation 12/17/201523Surrey Minischool - June 09 - Bentley 2m 3m Titanium fragments - simulations

12/17/2015 Surrey Minischool - June 09 - Identify Fragments through ENERGY, ENERGY LOSS and TIME-OF-FLIGHT Key UK Role: High timing resolution TIME-OF-FLIGHT array

12/17/2015 Surrey Minischool - June 09 - Bentley25 CVD Polycrystalline Diamond Project (York, Surrey, GSI, Diamond Detectors Ltd) Diamond Pros: Good timing resolution measured with Rel. H.I I. ~ ps FWHM Radiation Hard (10 6 pps easy) Diamond Cons: NO company makes fabricated diamond detectors Such large-areas not been tested VERY expensive DETECTOR of CHOICE =

12/17/2015 Surrey Minischool - June 09 - Bentley26 Reaction Target Time-of-flight “start” Time-of-flight “stop” UK will design and construct the “Diamond Wall” 0.3m

12/17/2015 Surrey Minischool - June 09 - Bentley27 Ordering of quantum levels: shell effects far from stability (spectroscopy of neutron rich nuclear matter) 100 Sn: 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) Science with HISPEC – some personal highlights How does our understanding of fundamental nuclear properties evolve as we move towards the extremes of nuclear existence?

12/17/2015 Surrey Minischool - June 09 - Bentley28 Nuclear Shells – cornerstone of understanding? The Nuclear Landscape Feature 1: Shell Effects

12/17/2015 Surrey Minischool - June 09 - Bentley29 Systematics of Ground-state Deformation Nuclear Shells – cornerstone of understanding?

Mass model predictions of nuclear masses for the Cs isotopes How good are Nuclear Models – how well are we doing? 12/17/ Surrey Minischool - June 09 - Bentley No problems where we have known masses (stars) but the various theoretical prescriptions diverge as soon as we move to unknown masses.

Wood-Saxon + spin-orbit diffuse surface + spin-orbit How does the ordering of quantum states alter? ‘ normal ’ ‘neutron rich’ Nuclear potential Why Exotic Nuclei – Magic Numbers in Danger....? 12/17/ Surrey Minischool - June 09 - Bentley

12/17/2015 Surrey Minischool - June 09 - Bentley32 Standard magic numbers: 2, 8, 20 New magic number: Why Exotic Nuclei – Magic Numbers in Danger....?

12/17/2015 Surrey Minischool - June 09 - Bentley Sn?

12/17/2015 Surrey Minischool - June 09 - Bentley34 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? 100 Sn? HISPEC: B(E2) of 0 + → Sn can be done

12/17/2015 Surrey Minischool - June 09 - Bentley35 The Nuclear Landscape: Neutron-Proton Symmetry Why Exotic Nuclei?

12/17/2015 Surrey Minischool - June 09 - Bentley MeV Neutron-Proton Symmetry

N=Z Z N Mirror Energy Differences (MED) 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 (differences of excitation energies) 12/17/ Surrey Minischool - June 09 - Bentley Coulomb Energy Differences

N=Z Z N Warner, Bentley, Van Isacker, NATURE Phys 2 (2006) /17/ Surrey Minischool - June 09 - Bentley Why Exotic Nuclei? – ISOSPIN Symmetry

12/17/2015 Surrey Minischool - June 09 - Bentley39 Why Exotic Nuclei? – ISOSPIN Symmetry What are the symmetry-breaking effects? Where in the nuclear landscape does the symmetry break down?

12/17/2015 Surrey Minischool - June 09 - Bentley40 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 Future research at HISPEC....

12/17/ Surrey Minischool - June 09 - Bentley A=53 T=3/2 analogue states 53 Mn – 3p removal 53 Ni – 3n removal First gamma-rays from T z = -3/2 system above 33 Ar. N=Z Z N

53 Mn 12/17/ Surrey Minischool - June 09 - Bentley Charge-Symmetry Breaking? 53 Ni = full shell model calculation (with CSB) = shell model calculations without CSB J=2 effect Question: Origin of this effect – where else does it appear? J.Brown et al, submitted to PRC (R) 2009 

Ni : At the limits of proton binding.... D.Rudolph et al, Phys. Rev. C78 (Rap. Comm.) /17/ Surrey Minischool - June 09 - Bentley PRL 97 (2006) % 98% 5(1)% 95(1)%

Surrey Minischool - June 09 - Bentley44 The Formalism of Isospin... (yuch) What is expected? T z -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 T z -dependence (  T=0) Rule 1: E1s identical in mirror nuclei ISOSPIN MIXING: T  T+1 and T+1  T components can break the rule..... E1 Rule 2: E2s:  B(E2)  T z ISOSPIN MIXING: T  T+1 and T+1  T components can break the rule..... Not tested – at least not systematically and accurately !

D E’E’ E”E” to the  ray detector 12 C 500  m 93 Nb 100  m  ”=0.28  ’=0.342 To particle identification 114 Pd  =0.354 E~70 MeV/uE’~60 MeV/uE”~44 MeV/u Incoming cocktail beam: … Ag, 15% 114 Pd ( ~ 1500pps), 112 Rh…… Differential Plunger Technique e.g. 114 Pd with Coulomb excitation 12/17/ Surrey Minischool - June 09 - Bentley Lifetimes at relativistic energies....

target/ degrader diameter: 4 cm target/ degrader separation: 0 - 2,5 cm precision : ~ 1 μm target/ degrader thickness: ~1μm -1mm 12/17/ Surrey Minischool - June 09 - Bentley Differential Plunger....

114 Pd: τ =118 (20) ps 110 Pd: τ=67 (8) ps A.Dewald et al. submitted to PRC/Rapid 12/17/ Surrey Minischool - June 09 - Bentley Differential Plunger....

12/17/ Surrey Minischool - June 09 - Bentley Isospin Symmetry in T=1 triplets, A~70 Analysis from B S Nara Singh et al, PRC (R) 2007 N=Z Z N Difference in excitation energy E A * - E B * A B

12/17/ Surrey Minischool - June 09 - Bentley Neutron-proton pairing effects ? Odd-odd nucleus dominated by T=1 np-pairs, hence fewer T=1 pp pairs... (see Lenzi PRC 60 (2001)021303) Isospin Symmetry in T=1 triplets, A~70

12/17/ Surrey Minischool - June 09 - Bentley Neutron-proton pairing effects ? Shape-changing effects ? Isospin Symmetry in T=1 triplets, A~70 R. Sahu et al, JPG 13, 603 (1987) Def Shell model calcs → Stretch in β 2 from 0.18 to 0.33  CED ~ -75 keV If β 2 changes from -0.3 to 0.35,  CED ~ -7 keV

74 Sr 74 Se 74 Kr /17/ Surrey Minischool - June 09 - Bentley Isospin Symmetry in T=1 triplets, A~70 Prediction: if “Shape effect” Prediction: if “Pairing effect” Question: what is the effect of shape-driving effects on isospin symmetry – different ground states?

NUclear STructure Astrophysics and Reactions HISPEC (but not alone!!) helps address all these questions: What are the limits for existence of nuclei? How does the nuclear force depend on varying proton-to- neutron ratios? How to explain collective phenomena from individual motion? How are complex nuclei built from their basic constituents? Which are the nuclei relevant for astrophysical processes and what are their properties? FAIR 12/17/ Surrey Minischool - June 09 - Bentley Hard work, and interesting times ahead