Proton Emission in Radioactive Decay Experimental Studies

Proton emission in radioactive decay experimental studies

J. Giovinazzo CENBG Foreword

Radioactivity an old science (120 years…) initially related to chemistry, then to physics (nuclear & particle)

first experimental probe to study atomic nucleus still a way to address many questions of the sub-atomic world

Objectives of the lecture focus on decay modes involving one or several protons emission give a flavor of the physics topics that can be addressed with these processes

questions considered from the experimental side Summary ● General considerations about radioactivity present the context of the decay modes involving proton emission basic and qualitative aspects ● Production of radioactive ions present the main techniques used to produce the nuclei of interest and study their radioactive decay ● Beta-delayed proton(s) emission illustrate with selected subjects the additional (sometimes unique) information that beta-delayed proton emission brings for our understanding of the atomic nucleus ● Proton(s) radioactivity experimental studies of these very exotic decay modes ● … if there’s a bit of time left… Proton emission in radioactive decay experimental studies

first session General consideration about radioactivity

○ Introduction  Brief overview of radioactive decay modes  Instability of atomic nucleus ○ Decay of proton-rich nuclei  Beta plus and the isospin formalism  Towards the proton drip-line General consideration about radioactivity

atomic nucleus  system of interacting fermions  2 types: protons & neutrons

protons number protons nuclear chart 3000 observed isotopes 250 stable ones

 the question of “stability”  binding energy & “drip-lines” neutrons number General considerations  Introduction  Radioactive decay modes

“usual” radioactive decays 1896

 emission 1934

1938/40 β+ decay

fission

protons number protons 1898

β decay

neutrons number General considerations  Introduction  Radioactive decay modes “exotic” radioactive decays

1982

1P radiactivity

2002 1984

2P radioactivity cluster rad.

protons number protons 1980

double β decay

neutrons number General consideration about radioactivity

any system tends to minimize its energy

radioactivity: spontaneous (no external perturbation) transformation of the nucleus to release energy

energy  mass (c2)

A  B + C1 + C2 + … + Q  conservation laws (quantum numbers: baryonic, leptonic, charge…)

Q = M(A) – [M(B) + M(C1) + M(C2) + …]

if Q > 0 the system (nucleus) A is instable (radioactive)

it decays to B, with emission of C1, C2… particles General considerations  Introduction  Instability of atomic nucleus

any system tends to minimize its energy

radioactivity: spontaneous (no external perturbation) transformation of the nucleus to release energy

energy  mass (c2)

A → B + C1 + C2 + … + Q

radioactivity (more official and etymological definition): focuses on the consequence, not the cause emission of particles / radiation (caused by this energy release) General considerations  Introduction  Instability of atomic nucleus

A → B + C1 + C2 + …

Q = M(A) – [M(B) + M(C1) + M(C2) + …]

nuclear stability is directly

related to masses mass excess mass we use mass excess: Δm = M − ( N + Z )u

mass parabola (same A = N + Z  β decay)

mass compilations usually give the atomic masses, with electrons rest mass & binding energy the “valley of (β) stability” General considerations  Introduction  Instability of atomic nucleus drip-lines and binding energy binding energy the part of the “mass energy” used to bind the system components

B(A,Z) = [ Z  mp + N  mn ] − Mnuc(A,Z) (similar to −Δm) curvature of the Bethe-Weizsäcker (liquid drop model) valley of stability

푩 푨, 풁 = 풂풗 ∙ 푨 volume ퟐ mass parabola − 풂풔 ∙ 푨ퟑ surface 풁 풁−ퟏ − 풂풄 ∙ ퟏ Coulomb 푨 ퟑ 푵−풁 ퟐ − 풂풂 ∙ ퟏ symmetry 푨 ퟑ −ퟏ ± 풂풑 ∙ 푨 ퟐ pairing + shell effects (magic numbers)…

© CC BY-NC-SA 4.0 – MIT OpenCourseWare General considerations  Introduction  Instability of atomic nucleus drip-lines and binding energy binding energy the part of the “mass energy” used to bind the system components

B(A,Z) = [ Z  mp + N  mn ] − Mnuc(A,Z)

separation energy (for protons)

SP(A,Z) = [ Mnuc(A−1,Z−1) + mp ] − Mnuc(A,Z) = B(A,Z) – B(A−1,Z−1)

S2P(A,Z) = [ Mnuc(A−2,Z−2) + 2mp ] − Mnuc(A,Z) = B(A,Z) – B(A−2,Z−2)

(proton) drip-line

if (SP < 0) or (S2P < 0)  last proton(s) not bound to the nucleus wrt the nuclear interaction General consideration about radioactivity

beta decay & isospin details for theory of beta decay and isospin formalism not presented here  textbooks

Fermi & Gamow-Teller transitions considering… ● isospin as a good quantum number ● only allowed transitions (most common case)

π π + ( Ti,TZi ; Ji )  ( Tf,TZf ; Jf ) for β : TZi  TZf = TZi + 1

Fermi (F) |Ji − Jf| = 0 ; πi π f = +1 ; |Ti − Tf| = 0 (coupling of e+ and ν to L = 0)

Gamow-Teller (GT) |Ji − Jf| ≤ 1 ; πi π f = +1 ; |Ti − Tf| ≤ 1 (coupling of e+ and ν to L = 1) (ΔJ = 0 forbidden for a 0+  0+ transition) General considerations  Decay of proton-rich nuclei  Beta plus and isospin formalism

isospin multiplet isospin as good quantum number & no Coulomb

ex.: T = 2 multiplet, A = 48

perfect N - Z symmetry

(≡ (≡ mass) T = 2 ퟒퟖ ퟒퟖ ퟐퟐ푭풆ퟐퟔ ퟐퟐ푻풊ퟐퟖ

energy T = 1 ퟒퟖ푴풏 ퟒퟖ푽 ퟐퟑ ퟐퟓ ퟐퟑ ퟐퟓ T = 0 ퟒퟖ ퟐퟒ푭풆ퟐퟒ

TZ = −2 TZ = −1 TZ = 0 TZ = +1 TZ = +2 General considerations  Decay of proton-rich nuclei  Beta plus and isospin formalism

isospin multiplet in real life (with Coulomb  curvature of the stability) ex.: T = 2 multiplet, A = 48 T = 2

ퟒퟖ푭풆 ퟐퟐ ퟐퟔ T = 2

T = 1 T = 2

(≡ (≡ mass) ퟒퟖ ퟐퟑ푴풏ퟐퟓ T = 1 T = 2

energy T = 0

ퟒퟖ T = 1 ퟐퟒ푭풆ퟐퟒ T = 2 ퟒퟖ ퟐퟑ푽ퟐퟓ ퟒퟖ ퟐퟐ푻풊ퟐퟖ

TZ = −2 TZ = −1 TZ = 0 TZ = +1 TZ = +2 General considerations  Decay of proton-rich nuclei  Beta plus and isospin formalism

beta plus & isospin for N < Z nuclei  Gamow-Teller & Fermi beta transitions 0 p n T = T Z

F + GT β+ / EC T (IAS)

GT T − 1

0 1 0 T Z < 0 |T Z|= |T Z |− 1 (N < Z) β+

(*) π + + for a J = 0  0 transitions, ΔJ = 0 is forbidden because Seν = 1 General considerations  Decay of proton-rich nuclei  Beta plus and isospin formalism

beta plus & isospin for N < Z nuclei  only Gamow-Teller (ΔT = 1) beta transitions 0 p n T = T Z

β+ / EC

GT T + 1

0 1 0 T Z > 0 |T Z|= |T Z |+ 1 (N > Z) β+ General consideration about radioactivity

+ β / EC ) 푨

푿풂 Xb

푵 (

P EC

S β and β-γ decays: Q - spectroscopy and γ nuclear structure 푨 - precision tests of weak 푵+ퟏ푿풃 Qβ+ = QEC − 2∙me interaction

+ β /EC decay energy: QEC  few MeV proton separation: SP(Xb) > QEC (B/A 8 MeV) General considerations  Decay of P-rich nuclei  Towards the proton drip-line

푨 푵푿풂 F IAS p

β+ / EC

EC Q γ

GT 푨−ퟏ )

푵+ퟏ푿풄 (+풑)

(

P S

푨 푵+ퟏ푿풃 QEC increases β-delayed proton emission: SP(Xb) decreases - nuclear astrophysics - gamma / proton competition proton transitions: precise probe General considerations  Decay of P-rich nuclei  Towards the proton drip-line

β-delayed multi- proton emission: - rp-process waiting points - search for direct 2P emission

푨 푵푿풂 F IAS 2p? β+ / EC

p EC

Q p γ GT 푨−ퟐ

γ 푵+ퟏ푿풅 (+ퟐ풑) ) Xb 푨−ퟏ푿풄 (+풑) (

푵+ퟏ 2p S

푨 푵+ퟏ푿풃

- often the only access to very exotic isotopes - complex proton emission patterns: level densities & statistical aspects General considerations  Decay of P-rich nuclei  Towards the proton drip-line

unbound with respect to proton(s) emission

2p 푨푿풂 1p 푵 푨−ퟏ 푨−ퟐ 푵푿풃 푵푿풄 (+풑) (+ퟐ풑) β+ / EC F IAS p SP(Xa) < 0 GT and/or p S2P(Xa) < 0 p

γ 푨−ퟐ 푨 푵+ퟏ푿풅 (+ퟐ풑) 푵+ퟏ푿풃 푨−ퟏ 푵+ퟏ푿풄 (+풑) Experimental techniques for proton emission decay studies

2. reaction in target 1. primary (stable) beam selectivity of the reaction ion, intensity & energy thickness / extraction of products

3. selection / separation separation capabilities (contamination)

4. collection & decay depends on the separation technique Experimental techniques  Production of radioactive ions General experiment scheme

main production reactions separation technique

transfer, charge exchange

fusion-evaporation ISOL facilities

spallation projectile fragmentation In-flight separators induced fission

various possibilities, different limitations Experimental techniques for proton emission decay studies

main production reactions separation technique

transfer, charge exchange transfer of few nucleons (1 or 2)  not far from stability fusion-evaporation ISOL facilities

spallation projectile fragmentation In-flight separators induced fission

mainly produces neutron-rich nuclei Experimental techniques  Production of radioactive ions  Production reactions Fusion-evaporation

residue formation cross section sensitive to energy

(Einc ≥ Coulomb barrier)  calculation codes: CASCADE(1), PACE(2), HIVAP(3), …

selectivity due to excitation energy available for evaporation

produces proton-rich residues projectile & target more suitable for ISOL technique (1) Intra-nuclear cascade (Monte-Carlo) (2) Projection-Angular momentum Coupling Evaporation (3) Heavy Ions Vaporization (statistical de-excitation) Experimental techniques  Production of radioactive ions  Production reactions Projectile fragmentation

high energy heavy ion projectile on target thin target: quasi-projectile with high forward momentum (higher beam energy  more focusing)

produce any fragments below (A,Z)proj both neutron-rich or deficient isotopes  requires a fragment separator 1st order: not sensitive to target nature (Be  high melting temp.) projectile obs. in A50 region: contrib. of proton pick-up from a Ni target perfectly adapted to in-flight technique Experimental techniques  Production of radioactive ions  Production reactions Projectile fragmentation

Cross-section evaluation Z = 28 codes: EPAX (empirical, several updates) experimental points: loss of a factor 2040 per

(2004) neutron removal ! B.Blank 56Ni beam (Z=28 !) on a Ni target  Zn (Z = 30)

Z = 26 courtesy of of courtesy Z = 30 56Zn

55Zn J.G., EPJA 11 (2001) 11 EPJA J.G., 52Ni 51 Z = 28 Ni

Z = 26 Experimental techniques  Production of radioactive ions  Production reactions Target spallation

high energy light projectile on heavy target (similar to fragmentation) light projectile (proton, deuton, …) and thick target  products need to be extracted from target intra-nuclear collisions / excitation  highly excited target + evaporation or (multi) fragmentation

can produce any nuclei below (A,Z)proj target both neutron-rich of deficient isotopes largely used with ISOL technique Experimental techniques for proton emission decay studies

○ Production of radioactive ions  Production reactions  Separation techniques ○ Experimental & detection techniques  For ISOL-type experiments  For fragmentation-type experiments Experimental techniques  Production of radioactive ions  Separation techniques Isotopic Separation Online (ISOL) – principles target-source ensemble reaction products stopped in a thick target (or in gas) source extraction: chemical selectivity (not all elements) (surface ionization, ECR/plasma, LASER excitation) limited efficiency, long release time low energy beams (few tens of keV) primary  excellent beam properties / manipulation beam target high resolution spectrometer ion source magnetic separation: m / Δm = 500020000 selection on A additional beam purification Penning trap / MR-ToF-MS high  precision measurements resolution  isomeric states separations spectrometer

additional purification nuclei deposit on thin catchers  adapted to decay studies ISOLDE @ CERN, IGISOL @ JYFL, ISAC @ TRIUMF… Experimental techniques  Production of radioactive ions  Separation techniques In-flight (fragments) separators – principles implantation-decay experiments half-lives from 1 µs  1 ms  few seconds (flight time through the separator)

projectile fragmentation of a high energy beam in a thin target fragments (quasi-projectile) with close to beam velocity no chemical selectivity / limitation – momentum dispersion fragment separator primary beam multiple stage separation (A & Z) cocktail beams or limited purity target balance between contamination & transmission

fragment  need for fragments identification separator implantation in thick stoppers (detectors)  particles from radioactive decay LISE @ GANIL (95 MeV/A) may not escape (protons) A1900 @ NSCL (160 MeV/A)  degraded energy resolution BigRIPS @ RIKEN (350 MeV/A)  100-1000 energy deposit factor FRS @ GSI (600-1000 MeV/A) between ions impl. and decay part. Experimental techniques  Production of radioactive ions  Separation techniques In-flight (fragments) separators – principles decay of very short lived nuclei (< 10 ns)  decay at target location

with high intensity beams emitted particles  high reactions rate detection primary  difficult detection environment beam target reaction tagging fragment from residue separator Experimental techniques  Production of radioactive ions  Separation techniques In-flight (fragments) separators – principles decay of very short lived nuclei (< 10 ns)  decay at target location

secondary beam production and selection

primary emitted particles beam detection target secondary reaction residue tagging fragment target separator

secondary beam ident. & tracking reaction channel selection Experimental techniques  Production of radioactive ions  Separation techniques Separation techniques comparison

ISOL In-flight

very high purity limited purity / mixed decay contributions point source on thin catcher thick catcher, large spot size chemical selectivity no element limitation

T1/2 > few 100 milliseconds T1/2 down to microseconds (or less) possibly very high statistics (less exotic) only access to most exotic nuclei minimum count rate (0.11 evt/s) down to < 1 evt/day   precision / high resolution discovery / pioneering experiments experiments

!!! highly complementary methods !!! (+ combining possibilities) Experimental techniques for proton emission decay studies

푨 푵푿풂 p β+ / EC p γ

푨−ퟐ푿풅 (+ퟐ풑) γ 푨−ퟏ 푵+ퟏ 푵+ퟏ푿풄 (+풑)

푨 푵+ퟏ푿풃 measurement:  beta decay half-life  proton transitions (E & intens.)  gamma transitions (E & intens.) Experimental techniques for proton emission decay studies

catcher cycles measurements (tape)  radioactive source collection

 pure beam …

60 keV J. Giovinazzo (2010) Giovinazzo J.

cycle

time Experimental techniques  Experiments & detection  ISOL experiment Isotopic Separation Online (ISOL) – typical experiment

gamma-rays cycles measurements detection (germanium)  radioactive source γ collection p  decay measurement

 …

β charged particles detection (e+,p)

(silicon) J. Giovinazzo (2010) Giovinazzo J.

cycle

time Experimental techniques  Experiments & detection  ISOL experiment Isotopic Separation Online (ISOL) – typical experiment

cycle cycles measurements

 radioactive source time collection

beta events time distribution  T1/2  decay measurement (+ instrumental corrections)

27Si – C.Magron (2016)  residual activity evacuation

69Se – J.G, EPJA (2000) (tape transport system)

event counts event event counts event time

proton energy (MeV) Experimental techniques  Experiments & detection  ISOL experiment Isotopic Separation Online (ISOL) – typical experiment

gamma detection spectroscopy (high resolution / low efficiency): Ge 2.5 keV @ 1 MeV new types of detectors: LaBr3, … Experimental techniques  Experiments & detection  ISOL experiment Isotopic Separation Online (ISOL) – typical experiment

charged particles (protons) detection

silicon diodes (1960): high resolution typical FWHM 2530 keV

cooled (alcohol) ≤ 1015 keV 69Se – J.G, EPJA (2000) ISOL exp.: p & β in diff. detectors - clean proton peaks

- surface barrier Si: small correction event counts event - recoil energy: Emes  EP  (1 − 1/A)

proton energy (MeV) β p Experimental techniques  Experiments & detection  ISOL experiment Isotopic Separation Online (ISOL) – typical experiment

charged particles (protons) detection

 silicon diodes ( 1960): high resolution gas Si typical FWHM 2530 keV cooled (alcohol) ≤ 1015 keV p p ISOL exp.: p & β in diff. detectors β β - clean proton peaks - surface barrier Si: small correction p use of telescopes for p/β pile-up - gas-Si  p/β discrimination β - Si-Si  β rejection Si Si Experimental techniques  Experiments & detection  ISOL experiment Isotopic Separation Online (ISOL) – typical experiment

charged particles (protons) detection H.O.U.Fynbo, Nucl. Phys. A 677 (2000)

silicon diodes (1960): high resolution typical FWHM 2530 keV cooled (alcohol) ≤ 1015 keV ISOL exp.: p & β in diff. detectors - clean proton peaks - surface barrier Si: small correction use of telescopes for p/β pile-up - gas-Si  p/β discrimination - Si-Si  β rejection

high granularity detectors: FUTIS (1998): gas-Si telescopes Si-cube (2009,CENBG) / Si-ball (2003, ISOLDE)

 for multi-particle emission (β-2p, β-3p, …) CENBG website, “Noyaux Exotiques” team Experimental techniques for proton emission decay studies

○ Production of radioactive ions  Separation techniques  Production reactions ○ Experimental & detection techniques  For ISOL-type experiments  For fragmentation-type experiments Experimental techniques  Experiments & detection  In-flight experiment Implantation-decay experiments for half-lives from 0.1  1 ms  few seconds Experimental techniques  Experiments & detection  In-flight experiment In-flight (fragments) separators – typical experiment

thick implantation implantation events detector (silicon)

J. Giovinazzo (2008) Giovinazzo J.  identification of fragments

cocktail beam (high E)

J.G, E666@GANIL (2016) unbound 52Ni 51Ni 50Co 50Ni fragments ident.: ΔE, ToF 48 Fe 47 (silicon, plast. scint…) Fe 46 46Mn Fe 44Cr continuous (random) implantation 43Cr

time Experimental techniques  Experiments & detection  In-flight experiment In-flight (fragments) separators – typical experiment

gamma-rays protons decay events detection (Ge) detection (impl. det.)

J. Giovinazzo (2008) Giovinazzo J.  proton emitted & γ stopped in implantation detector p β  beta escaping: - partial energy deposit - neighbor detectors

beta detection

decay events mixed with implantations no direct assignment of a decay event to an identified implantation !!!  specific correlation procedure time Experimental techniques  Experiments & detection  In-flight experiment In-flight (fragments) separators – typical experiment implantation-decay correlations correlate all decay events (unknown emitting nucleus) with all implantations of studied nucleus (ex. 52Ni) – in a finite time window  only 1 correlation is “good” (impl. occurs before corresponding decay)

 other (wrong) correlations

positive correl. time impl. event [k] ≡ id[k] ; timp[k] decay event [j] ≡ tdec[j] ; Edec[j] negative correl. time Δt correlation [j,k] ≡ { id[k] ; Edec[j]; Δt [j,k] = tdec[j] − timp[k] }

52Ni decay Experimental techniques  Experiments & detection  In-flight experiment In-flight (fragments) separators – typical experiment implantation-decay correlations correlate all decay events (unknown emitting nucleus) with all implantations of studied nucleus (ex. 52Ni) – in a finite time window  only 1 correlation is “good” (impl. occurs before corresponding decay)

decay time: exponential probability  T1/2  other (wrong) correlations: flat random background

positive correl. time decay time distribution (all possible correlation) negative correl. time Δt good correlations

wrong correlations ● negative time ● positive time

52Ni decay Experimental techniques  Experiments & detection  In-flight experiment In-flight (fragments) separators – typical experiment implantation-decay correlations correlate all decay events (unknown emitting nucleus) with all implantations of studied nucleus (ex. 52Ni)  1 decay event may be correlated to several implantations  multiple counts in energy distributions

S(E) = SΔt>0(E) − SΔt<0(E) on a statistical basis !!!

correlated events remove contamination decay energy from decay of other nuclei decay time remove self-contamination (for correct intensities)

J.G, E666@GANIL (2016) increased statistical fluctuations Experimental techniques  Experiments & detection  In-flight experiment In-flight (fragments) separators – typical experiment implantation-decay correlations

event rates considerations

impl.: nimp / s decay: ndec / s correl.: ncor = ndec  nimp / s

nimp  ndec  200/s  ncor  40 000/s only 1/200 being good (0.5%) !!!

use of stripped silicon detectors (DSSSD) only impl. and decays in same pixel ex.: (NX=10 ; NY=10) DSSSD  reduction of wrong & uniform implantation in DSSSD correlations  nimp  ndec  2/pixel/s  ncor  4/pixel/s  1/4 good corr. (25%) Experimental techniques  Experiments & detection  In-flight experiment In-flight (fragments) separators – typical experiment implantation-decay correlations emitted protons detection implantation inside a thick detector p (Si: 300 1000 µm) ion decay from implantation location β  beta & proton emitted simultaneously at electronics scale  protons stopped inside implantation (5 MeV proton range 150 µm) (thick) detector  β escapes the detector

E P

p E Experimental techniques  Experiments & detection  In-flight experiment In-flight (fragments) separators – typical experiment implantation-decay correlations emitted protons detection implantation inside a thick detector p (Si: 300 1000 µm) ion decay from implantation location C.Dossat, NPA 792 (2007) β  beta & proton emitted simultaneously at electronics scale  protons stopped inside (5 MeV proton range 150 µm)  β escapes the detector

multiple proton emission β2p p  no individual protons β information β p p p Experimental techniques  Experiments & detection  In-flight experiment In-flight (fragments) separators – typical experiment implantation-decay correlations emitted protons detection implantation inside a thick detector p (Si: 300 1000 µm) ion decay from implantation location β  beta & proton emitted simultaneously at electronics scale  protons stopped inside: full EP deposit implantation (5 MeV proton range 150 µm) (thick) detector

 β escapes the detector: partial ΔEβ deposit

measured energy

Emes = EP + ΔEβ EP  shifted transition energy  degraded resolution E but 100% efficiency ! Eβ mes Experimental techniques  Experiments & detection  In-flight experiment In-flight (fragments) separators – typical experiment implantation-decay correlations emitted protons detection implantation inside a thick detector implantation in a TPC (Si: 300 1000 µm) (particles tracking) decay from implantation location  beta & proton emitted simultaneously at electronics scale

 protons stopped inside: full EP deposit (5 MeV proton range 150 µm)

 β escapes the detector: partial ΔEβ deposit

measured energy

Emes = EP + ΔEβ EP  shifted transition energy  degraded resolution E but 100% efficiency ! Eβ mes Experimental techniques  Experiments & detection ISOL / In-flight experiments comparison

32Ar β-p decay @ ISOLDE & MSU

(used for complementary analysis)

, PPNP (2008) (2008) PPNP ,

M.J.G.Borge

& &

B.Blank

, adapted from from adapted ,

Melconian D. D. Experimental techniques  Experiments & detection Corrections to experimental data

measurement of proton transitions - time (or time diff.)  half-life - energy peak: position  transition energy integral  intensity

skip Experimental techniques  Experiments & detection Corrections to experimental data

measurement of proton transitions - time (or time diff.)  half-life - energy peak: position  transition energy integral  intensity logic signals decision Energy corrections (trigger) ISOL: recoil of nucleus detectors storage in-flight: ΔEβ pile-up control processing analysis (coding) Intensity corrections measured quantities ● detection efficiency: Imes / εdet ns  μs 110 μs 0.11 ms ● acquisition system dead-time - missed events because acq. busy (processing previous event) - typical DT: 1001000 μs increasing number of channels (DSSSD,…) new technologies (standard for comm. protocols) Experimental techniques  Experiments & detection Corrections to experimental data

measurement of proton transitions - time (or time diff.)  half-life - energy peak: position  transition energy integral  intensity single data Energy corrections channel proc. ISOL: recoil of nucleus single data storage in-flight: ΔEβ pile-up channel proc. control single data analysis Intensity corrections channel proc.

data reconstruction event ● detection efficiency: Imes / εdet single channel proc. ● acquisition system dead-time - missed events because acq. busy ns  μs 10 μs (processing previous event) - typical DT: 1001000 μs increasing number of channels (DSSSD,…)  “triggerless” DAQ new technologies (standard for comm. protocols) Experimental techniques  Experiments & detection Corrections to experimental data

measurement of proton transitions - time (or time diff.)  half-life - energy peak: position  transition energy integral  intensity

Energy corrections ISOL: recoil of nucleus

in-flight: ΔEβ pile-up

Intensity corrections

● detection efficiency: Imes / εdet ● acquisition system dead-time - missed events because acq. busy (processing previous event) - typical DT: 1001000 μs increasing number of channels (DSSSD,…)  “triggerless” DAQ new technologies (standard for comm. protocols) Experimental techniques  Experiments & detection Decay intensity correction

ISOL decay (cycles) experiment real decay events  collection-decay phases  non uniform DT fraction: measured decay events distorted decay rate curve ퟏ count events 푵 ≈ 풏풎풆풔 풕 ∙ ∙ 풅풕 ퟏ− 푫푻 풆풗풕∙풏풎풆풔 풕 time uncorrected fit induces an error on T1/2 Experimental techniques  Experiments & detection Decay intensity correction

ISOL decay (cycles) experiment real decay events  collection-decay phases  non uniform DT fraction: measured decay events distorted decay rate curve ퟏ count events 푵 ≈ 풏풎풆풔 풕 ∙ ∙ 풅풕 ퟏ− 푫푻 풆풗풕∙풏풎풆풔 풕 in-flight implantation-decay experiment time  continuous implantation and decay uniform dead-time fraction implantations / decay events

푵 풅풆풄 푵(풅풆풄) ≈ 풎풆풔 ퟏ− 𝝆푫푻 time (풂풍풍) 푵풎풆풔 ∙ 푫푻 풆풗풕 𝝆푫푻 ~ 푻풆풙풑 ퟏ 푷 = ퟏ − 풆−흀∙ 푫푻 푵 ≈ 푵 ∙  systematic loss after 풎풆풔 풆−흀∙ 푫푻 implantation: depends on T1/2 decay prob.

DTevt Experimental techniques  Experiments & detection Decay intensity correction

ISOL decay (cycles) experiment real decay events  collection-decay phases  non uniform DT fraction: measured decay events distorted decay rate curve ퟏ count events 푵 ≈ 풏풎풆풔 풕 ∙ ∙ 풅풕 ퟏ− 푫푻 풆풗풕∙풏풎풆풔 풕 in-flight implantation-decay experiment time  continuous implantation and decay uniform dead-time fraction implantations / decay events

푵 풅풆풄 푵(풅풆풄) ≈ 풎풆풔 ퟏ− 𝝆푫푻 time (풂풍풍) 푵풎풆풔 ∙ 푫푻 풆풗풕 𝝆푫푻 ~ 푻풆풙풑 ퟏ 푷 = ퟏ − 풆−흀∙ 푫푻 푵 ≈ 푵 ∙  systematic loss after 풎풆풔 풆−흀∙ 푫푻 implantation: depends on T1/2 decay prob. + pile-up corrections (coinc. or random) nd  2 order corrections (precision measurements) DTevt Beta-delayed proton(s) emission

○ Beta-delayed 1 proton emission  Fermi transition & isospin symmetry  β-p and Gamow-Teller strength distribution  Proton emission and nuclear levels half-life ○ Beta-delayed multi-proton  Sequential vs direct emission  First experiment  β-2p and search for the “2He” emission  Delayed multi-proton emission Beta-delayed proton(s) emission

Historical milestones

beta delayed proton emission

1963 first observation: Karnaukhov et al., conf. proc. 1963 20Ne  (Ni,Ta) target, precursor was not identified first precursor: 25Si, R. Barton, et al., Can. J. Phys. 41 (1963) 2007

1966 ten precursors: V.I. Goldanskii, Ann. Rev. Nuclear Sci. (1966)

1977 40 known J. Cerny, J.C. Hardy, Ann. Rev. Nuclear Sci. (1977) … today 160 known

beta delayed multi-proton emission β-2p first case: 22Al (Cable et. al, 1983), today 15 identified cases β-3p few cases, not much to learn Beta-delayed proton(s) emission

Delayed-proton(s) emission: a rich physics case !

푨 푵푿풂 F IAS

β+ / EC

p EC

Q p γ 2p? GT 푨−ퟐ

γ 푵+ퟏ푿풅 (+ퟐ풑) ) Xb 푨−ퟏ푿풄 (+풑) (

푵+ퟏ 2p S

푨 푵+ퟏ푿풃 Beta-delayed proton(s) emission

Delayed-proton(s) emission: a rich physics case !

β(F)-p: IMME (masses) isospin mixing

푨 푵푿풂 F IAS

β+ / EC

p EC

Q p γ 2p? GT 푨−ퟐ

γ 푵+ퟏ푿풅 (+ퟐ풑) ) Xb 푨−ퟏ푿풄 (+풑) (

푵+ퟏ 2p S

푨 푵+ퟏ푿풃 Beta-delayed proton(s) emission

Delayed-proton(s) emission: a rich physics case !

β(F)-p: IMME (masses) isospin mixing

β(GT)-p: nuclear structure deformation isospin symmetry 푨 푵푿풂 F IAS

β+ / EC

p EC

Q p γ 2p? GT 푨−ퟐ

γ 푵+ퟏ푿풅 (+ퟐ풑) ) Xb 푨−ퟏ푿풄 (+풑) (

푵+ퟏ 2p S

푨 푵+ퟏ푿풃 Beta-delayed proton(s) emission

Delayed-proton(s) emission: a rich physics case !

β(F)-p: IMME (masses) isospin mixing

β(GT)-p: nuclear structure deformation isospin symmetry 푨푿풂 푵 F p / γ: nuclear astrophysics IAS resonances close to SP

β+ / EC

p EC

Q p γ 2p? GT 푨−ퟐ

γ 푵+ퟏ푿풅 (+ퟐ풑) ) Xb 푨−ퟏ푿풄 (+풑) (

푵+ퟏ 2p S

푨 푵+ퟏ푿풃 Beta-delayed proton(s) emission

Delayed-proton(s) emission: a rich physics case !

β(F)-p: IMME (masses) isospin mixing

β(GT)-p: nuclear structure deformation isospin symmetry 푨푿풂 푵 F p / γ: nuclear astrophysics IAS resonances close to SP

β+ / EC

p EC

Q p γ 2p? GT 푨−ퟐ

γ 푵+ퟏ푿풅 (+ퟐ풑) ) Xb 푨−ퟏ푿풄 (+풑) (

푵+ퟏ 2p S

푨 2 푵+ퟏ푿풃 2p ( He) emission Beta-delayed proton(s) emission

Isobaric Multiplet Mass Equation (IMME, Wigner, 1957) charge independent strong nuclear interaction + Coulomb 2 M(TZ) = a + bTZ + cTZ (+ possible higher order correction)

T  (2T+1) projections TZ if (T ≥ 3/2)  at least 4 values of TZ  if 3 masses are known, determination of (a,b,c) coefficients  mass estimate of other multiplet members

T = 3/2

T = 3/2 T = 3/2 T = 3/2

T = 1/2 T = 1/2

TZ = −3/2 TZ = −1/2 TZ = +1/2 TZ = +3/2 Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry A first access to the mass of exotic nuclei

Isobaric Multiplet Mass Equation (IMME, Wigner, 1957) charge independent strong nuclear interaction + Coulomb 2 M(TZ) = a + bTZ + cTZ (+ possible higher order correction)

T  (2T+1) projections TZ if (T ≥ 3/2)  at least 4 values of TZ  if 3 masses are known, determination of (a,b,c) coefficients  mass estimate of other multiplet members

T = 2 more values: test of the quadratic form

T = 2 T = 2 T = 2 T = 2 T = 1 T = 1 T = 1 T = 0

TZ = −2 TZ = −1 TZ = 0 TZ = +1 TZ = +2 Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry A first access to the mass of exotic nuclei

for nuclei far from stability (with Z > N) Fermi transition to IAS + proton emission precise proton transition energy less exotic daughter (usually better known  mass)  estimate of IAS mass (excess) other multiplet members less exotic  use IMME for precursor ground state mass

T = 3/2 β (F)

T = 3/2 T = 3/2 T = 3/2 p T = 1/2 T = 1/2

TZ = −3/2 TZ = −1/2 TZ = +1/2 TZ = +3/2 Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry A first access to the mass of exotic nuclei

A = 41 41Ti decay 41Ti T = 3/2 Jπ = 3/2+ 40 41 , NP A792 (2007) A792 NP , Δm( Ca) = −34846.3 (2) keV Sc

Ep(IAS40Ca) = 4852.8 (26) keV .Dossat

C 41 40 41 Δm( Sc IAS) = Δm( Ca) + ΔmP + EP Ca = −22704.6 (26) keV 41K Δm(41Ca) = −29318.8 (20) keV Δm(41K) = −22704.7 (24) keV T = 3/2  Δm(41Ti) = −15716.9 (73) keV β (F) 41 Ti T = 3/2 T = 3/2 T = 3/2 p 41K T = 1/2 40 T = 1/2 41Sc Ca (+p) 41Ca

TZ = −3/2 TZ = −1/2 TZ = +1/2 TZ = +3/2 Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry A first access to the mass of exotic nuclei

52Ni decay Δm(52Co IAS) = Δm(51Fe) 52Ni A = 52 T = 2 + ΔmP 51 52 π + , NP A792 (2007) A792 NP , + EP(IAS Fe) Co J = 0 52 .Dossat + Δm( Fe T=2) C 52Fe + Δm(52Mn T=2) 52 + Δm( Cr T=2) 52Mn  4 multiplet members  Δm(52Ni) = −22639 (33) keV 52Cr T = 2  test of IMME: β (F) cubic term compatible with 0 52Ni T = 2 T = 2 T = 2 p T = 2 T = 1 52Cr 51 T = 1 T = 1 52 Fe Co (+p) T = 0 52Mn 52Fe TZ = −2 TZ = −1 TZ = 0 TZ = +1 TZ = +2 Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry A first access to the mass of exotic nuclei

experiment @ GANIL / LISE3 56Zn comparison of masses from IMME (exp.) 56Cu with A.M.E. 52Ni 56Ni 52Co 56Co 48Fe 52Fe 56Fe S.E.A. Orrigo et al., PRC 93 (2016) 48Mn 52Mn 48Cr 52Cr 48V 48Ti Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry A first access to the mass of exotic nuclei

Coulomb displacement energy if less than 3 masses are known  parametrization of Coulomb displacement between analog states M.S. Antony et al., Nuc. Data Tables (1997)

ퟏ −

횫푬푪 = 풂 푻 ∙ 풁 ∙ 푨 ퟑ + 풃 푻 . Data Tables (1997) Tables Data .

IMME precision does not compete with Nuc current mass measurement techniques (only measurement for very exotic) Δm / m = (IMME) 10−5-10−6 (cyclo+ToF) 10−5-10−6 al., et Antony M.S. (storage ring) 10−6 (Penning trap) 10−7-10−8 Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry Proton emission from IAS and isospin mixing

gamma de-excitation: electromagnetic process proton emission: strong nuclear interaction process

 proton emission faster above SP

tot

tot Γ

β /

/ /

= =

)

(

( P

p P

SP γ

0 1 Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry Proton emission from IAS and isospin mixing

Fermi transition + proton emission (from IAS): isospin forbidden E* T, TZ (< 0)

β(F) T, TZ+1 IAS t =1/2 p γ SP

T−3/2, TZ+3/2 T−1 0 Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry Proton emission from IAS and isospin mixing

Fermi transition + proton emission (from IAS): isospin forbidden

observation of protons from IAS  E* isospin symmetry breaking T, TZ (< 0)  emission possible due to a fraction of mixing with T−1 states of the IAS

“forbidden” proton transition (slower) β(F) competition with gamma de-excitation T, TZ+1 IAS experimental information to T−1 t =1/2 p test isospin impurity γ SP  test INC terms in nuclear interaction (not well known) T−3/2, TZ+3/2 T−1  … 0 Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry Proton emission from IAS and isospin mixing

simple 2-state mixing picture | 푰푨푺 = ퟐ ퟏ − 휶ퟐ ∙ | 푻 = ퟐ + 휶 ∙ | 푻 = ퟏ

푻=ퟏ ퟐ

E* 횪푷 = 횪풔.풑. ∙ 휶 ∙ 푺푻=ퟏ T=2, TZ=−2 풆풙풑 푰푷 횪푷 ○ single particle width for isospin allowed 풆풙풑 = transition 푰휸 횪휸 ○ spectroscopic factor for allowed trans.

β(F) 풆풙풑 푰 횪휸 T=2, TZ=−1 ퟐ 푷 IAS 휶풆풔풕풊풎 = 풆풙풑 × 푻=ퟏ 푰휸 횪풔.풑. ∙ 푺푻=ퟏ T=1 t =1/2 p γ experimental measurements SP

T=1/2, TZ=−1/2 theoretical calculations T=1 횪 shell model 0 휸 푺 shell model 횪풔.풑. barrier penetration Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry Proton emission from IAS and isospin mixing

experiment by-product in A50 mass region with T=2 (Dossat et al., NP A792, 2007)  trigged an experimental / theoretical program (B. Blank et al., E666 exp. 2016; N. Smirnova et al., PRC95 2017) try to understand the estimated isospin mixing  put experiment constraints on theoretical calculations

휶ퟐ (%)

28 % in mirror  dev. of shell model  33 % B.Blank et al., GANIL/E666 proposal (2015)

require improved β-p(γ) (final state) and β-γ (for Γγ calc.) data Beta-delayed emission  β-1p emission  Fermi transition & isospin symmetry

Proton emission from IAS and isospin mixing

2014)

(

PRL 112 PRL 112

., ., et al et 휶ퟐ = 33 ± 10 %

Orrigo (28 ± 1 % in mirror 56Fe) S.E.A. S.E.A.

very rare case of beta-gamma-proton decay - proton emission isospin-forbidden - gamma de-excitation to an unbound state Beta-delayed proton(s) emission

푩 푮푻 ∝ 풇 𝝈흉 풊 ퟐ

 probe the nuclear structure far from stability high selectivity of populated states (selection rules) test of nuclear models - predicted half-lives 2 2 - sum rule & quenching factor (q = B(GT)exp / B(GT)th  0.7 ) - deformation - proton-neutron pairing (along N = Z) - … Beta-delayed emission  β-1p emission  GT strength distribution Gamow-Teller strength distribution

푩 푮푻 ∝ 풇 𝝈흉 풊 ퟐ E*

close to stability only a small fraction of the GT strength is accessible

from beta decay

ퟐ 𝝈흉 β+ / EC

0 Beta-delayed emission  β-1p emission  GT strength distribution Gamow-Teller strength distribution

푩 푮푻 ∝ 풇 𝝈흉 풊 ퟐ E*

+ β / EC far from stability

large QEC window probe an important fraction ퟐ

of the GT strength 𝝈흉

0 Beta-delayed emission  β-1p emission  GT strength distribution Gamow-Teller strength distribution

∗ 푰휷/푬푪(푬 ) ퟐ E* 푩 푮푻 ∝ 풇 𝝈흉 풊 ∝ ∗ 풇휷/푬푪(풁, 푸휷 − 푬 ) ∙ 푻ퟏ/ퟐ

ퟓ ∗ −ퟓ 풇~푬휷 ~ 푸휷 − 푬

β+ / EC

∗

푬

휷

풇

ퟐ

푬푪

휷

푬푪

퐥퐨퐠

푰

풇

𝝈흉 퐥퐨퐠

−

β Q Beta-delayed emission  β-1p emission  GT strength distribution Gamow-Teller strength distribution

푰 (푬∗) ퟐ 휷/푬푪 푩 푮푻 ∝ 풇 𝝈흉 풊 ∝ ∗ 풇휷/푬푪(풁, 푸휷 − 푬 ) ∙ 푻ퟏ/ퟐ

| 풊

experimental data + β / EC  T1/2 (decay time dist.)  Iβif (full decay scheme) high energy very high density of states ∗ − 풂∙푬∗ ∗ 𝝆 푬 ∝ 풆 푬

| 풇 푬푪

low energy / 휷 resolved transitions 푰 Beta-delayed emission  β-1p emission  GT strength distribution Gamow-Teller strength distribution

푰 (푬∗) ퟐ 휷/푬푪 푩 푮푻 ∝ 풇 𝝈흉 풊 ∝ ∗ 풇휷/푬푪(풁, 푸휷 − 푬 ) ∙ 푻ퟏ/ퟐ

| 풊

experimental data + β / EC  T1/2 (decay time dist.)  Iβif (full decay scheme) high energy very high density of states ∗ − 풂∙푬∗ ∗ 𝝆 푬 ∝ 풆 푬

| 풇 푬푪

low energy / 휷 resolved transitions 푰 Beta-delayed emission  β-1p emission  GT strength distribution Gamow-Teller strength distribution

푰 (푬∗) ퟐ 휷/푬푪 푩 푮푻 ∝ 풇 𝝈흉 풊 ∝ ∗ 풇휷/푬푪(풁, 푸휷 − 푬 ) ∙ 푻ퟏ/ퟐ

large fraction for the B(GT) above proton β+ / EC proton emission separation energy

∗ P 푬

gamma

푬푪 /

de-excitation 휷 푰 Beta-delayed emission  β-1p emission  GT strength distribution Gamow-Teller strength distribution

proton detection: only access to high E* states

efficient and precise probe  even for low proton branching

푷

풕풐풕 횪

β+ / EC 횪

∝

푷 푰

∗ P

푬

푬푪

휷 푰 Beta-delayed emission  β-1p emission  GT strength distribution

B(GT) in light nuclei: decay of 25Si @ GANIL (in-flight)

., EPJA (2004) EPJA .,

et al et

C. Thomas C.

- J.

resolved transitions comparison

with shell model

., OXBASH / USD int. USD / OXBASH .,

et al et

, ,

Brwon B.A. B.A. Beta-delayed emission  β-1p emission  GT strength distribution B(GT) in light nuclei: decay of 33Ar @ GANIL (ISOL)

resolved

transitions

., PRC (2010) PRC .,

et al et

Adimi N. N.

SP Beta-delayed emission  β-1p emission  GT strength distribution B(GT) and nuclear deformation

signature of shape )

., transition along N = Z

2 (

et al et influence of deformation E

on B(GT) distribution Phys. Lett. B253 (1991) B253 Lett. Phys.

W.Gelletly (HF+BCS+QRPA)

., Z. Phys. A353 (1995) A353 Phys. Z. .,

et al et

., Phys. Rev. C64 (2001) C64 Rev. Phys. .,

et al et

Hamamoto

I. I. P.Sarriguren Beta-delayed emission  β-1p emission  GT strength distribution B(GT): decay of 72Kr and 76Sr @ ISOLDE

76Sr S P β2 = 0.4

gamma proton

., Phys. Rev. Lett. 92 (2004) 92 Lett. Rev. Phys. .,

et al et E.Nacher

few percent only as proton emission in these cases  becomes more important for more exotic nuclei (A. Algora exp. @ RIKEN: 70,71Kr) Beta-delayed emission  β-1p emission  GT strength distribution B(GT) distribution: experimental difficulties the “pandemonium” effect (beta-gamma spectroscopy) J.Hardyet al., Phys. Lett. B71 (1977)

푰휷 풇 determination β  transitions populating f: - direct beta feeding 푰휷 풇 - gamma from states fed by β at higher energy: 푰 풊 → 풇 | 풇 풊 휸  transitions depopulating f: - gamma to low energy states: 풋 푰휸 풇 → 풋

푰휷 풇 = 풋 푰휸 풇 → 풋 − 풊 푰휸 풊 → 풇 Beta-delayed emission  β-1p emission  GT strength distribution B(GT) distribution: experimental difficulties the “pandemonium” effect (beta-gamma spectroscopy) J.Hardyet al., Phys. Lett. B71 (1977)

high resolution gamma spectroscopy  low energy states β - significant β feeding - low nuclear states density - “easily” observed Beta-delayed emission  β-1p emission  GT strength distribution B(GT) distribution: experimental difficulties the “pandemonium” effect (beta-gamma spectroscopy) J.Hardyet al., Phys. Lett. B71 (1977)

high resolution gamma spectroscopy  low energy states β - significant β feeding - low nuclear states density - “easily” observed  high energy states - weak β feeding - high level density - gamma de-excitation: ● few high energy gamma-rays  no detection efficiency ● many low energy gamma-rays  fragmented strength: too low intensity

missed B(GT) strength at high excitation energy !!! Beta-delayed emission  β-1p emission  GT strength distribution B(GT) distribution: experimental difficulties the “pandemonium” effect (beta-gamma spectroscopy) J.Hardyet al., Phys. Lett. B71 (1977)

use of a total absorption spectrometer (TAS)  gamma “calorimeter”

β  need for additional β-p discrimination (telescope)

. Part. Phys. 44 44 (2017) Phys. Part. .

Nucl

J. Phys. G: Phys. J.

., .,

et al et B.Rubio Beta-delayed emission  β-1p emission  GT strength distribution B(GT) distribution: experimental difficulties

proton emission to excited states

∗

푷 푬 β-p to ground state 푬 β

p 푷

푬 SP

푷

푰

∗

푬

휷 푰 Beta-delayed emission  β-1p emission  GT strength distribution B(GT) distribution: experimental difficulties

proton emission to excited states

∗

푷

푬 푬 β-p to excited state 푬 β p

γ 푷

푬 SP

푷

푰

∗

푬

휷 푰 Beta-delayed emission  β-1p emission  GT strength distribution B(GT) distribution: experimental difficulties

proton emission to excited states

∗

푷

푬

푬 푬

β p

γ 푷

푬 SP

푷

푰

∗

푬

휷 푰

resolved transitions: (β-)p-γ coincidences  OK high exc. energy: need for (very) high statistics for p-γ coincidences to disentangle contributions (or statistical analysis  no detailed spectroscopy) Beta-delayed emission  β-1p emission  GT strength distribution B(GT): test of isospin symmetry far from stability

+ β decay  charge exchange (p,n) ; (3He,t) mirror processes

𝝈흉 𝝈흉 T T

IAS 흉 IAS limitation

ퟓퟔ ퟓퟔ window

ퟐퟔ풁풏ퟑퟎ 𝝈흉 ퟑퟎ푭풆ퟐퟔ E*

no no Q 𝝈흉 ퟓퟔ푪풖 ퟓퟔ푪풐

TZ = −T TZ = −T+1 TZ = T−1 TZ = +T ∗ 푰휷(푬 ) 휹𝝈 푩 푮푻 ∝ ∗ 푩 푮푻 ∝ ퟎ° 풇(풁, 푸휷 − 푬 ) ∙ 푻ퟏ/ퟐ 휹훀 Beta-delayed emission  β-1p emission  GT strength distribution B(GT): test of isospin symmetry far from stability

56Zn 56Cu

56 2014)

( Ni 56Co

56Fe

Phys. Rev. Lett. 112 112 Lett. Rev. Phys.

., ., et al et

Orrigo good agreement with S.E.A. S.E.A. mirror symmetry

indication of non resolved proton transitions (close to IAS) Beta-delayed emission  β-1p emission  GT strength distribution B(GT): test of isospin symmetry far from stability

β+ decay data at GSI, GANIL prog. @ RIKEN A. Algora, B. Rubio, et al. (IFIC Valencia)

(p,n) & (3He,t) data at RCNP Osaka Y. Fujita, et al. (Osaka) Beta-delayed proton(s) emission

to β-2p

to WISArD Beta-delayed emission  β-1p emission  Nuclear levels half-life Particle – X-ray coincidence technique (PXCT) proposed by J.C. Hardy (PRL 37, 1976) very elegant technique, despite not much used  X-ray emission from atomic rearrangement after electron capture

XZ-1 X-ray energy depends on the element (Z) X A Z-2 Z (in reality, not only EC K-electrons) p

γ EX

A-1Z-2 AZ-1 Beta-delayed emission  β-1p emission  Nuclear levels half-life Particle – X-ray coincidence technique (PXCT) proposed by J.C. Hardy (PRL 37, 1976) very elegant technique, despite not much used  X-ray emission from atomic rearrangement after electron capture

XZ-1 X-ray energy depends on the element (Z) X A Z-2 Z (in reality, not only EC K-electrons) p

γ EX

A-1 Z-2 proton - X-rays coincidence measurement AZ-1

with EX gates on EP distribution: X 푵 푬 푷 풁−ퟐ p 푹푿 푬푷 = 푵 푬푷 풁−ퟏ Beta-delayed emission  β-1p emission  Nuclear levels half-life Particle – X-ray coincidence technique (PXCT)

푵 푬푷 풁−ퟐ  depends if proton emission is faster than 푹푿 푬푷 = 푵 푬푷 풁−ퟏ atomic rearrangement  known atomic process (atomic data tables) in the range 2−15 s (carbon) to 6−18 s (uranium)

comparable with (some) proton emission from nuclear states (depends on energy, angular momentum…)

probability analysis of processes order (1) EC – γ  X(Z−1) ; no proton detected (2) EC (– X) – p  X(Z−1) with proton (3) EC – p (– X)  X(Z−2) with proton

횪푿 횪푷 푵 푬푷 풁−ퟏ = 푵 푬푷 ퟎ ∙ ∙ 횪푷+횪휸+횪푿 횪푷+횪휸 횪푷 + 횪휸 흉푿 푹푿 푬푷 = = 횪푷 횪푿 흉풏풖풄 푵 푬푷 풁−ퟐ = 푵 푬푷 ퟎ ∙ 횪푷+횪휸+횪푿 Beta-delayed emission  β-1p emission  Nuclear levels half-life Particle – X-ray coincidence technique (PXCT)

for resolved states  direct measurement of the nuclear lifetime

for unresolved states  average behavior ., EPJA (2004) EPJA .,

statistical model analysis, sensitive to al et - level density parameter J.C. Hardy et al., PLB 77 (1978)

- proton / gamma width models Thomas C.

- J.

applied in A  70 mass region

(for TZ = 1/2  only GT)

J.G. et al., N.P. A674 (2000) 72 73 NX( Se) / NX( Br) in β-p decay of 73Kr

to WISArD Additional selected topics

○ Delayed proton emission to test weak interaction ○ ACTAR TPC Selected topics  β-p to test weak interaction Weak interaction currents

general form of the β+ hamiltonien ν 푪′풊 푯휷+~ 푪풊 풖 풑푶풊풖풏 풖 풆푶풊 ퟏ − 휸ퟓ 풖흊 e+ 푪풊 p n 5 types of operators to satisfy Lorentz invariance S scalar 1 V vector 휸풊 휸풊 the Dirac matrices ퟏ 𝝈 = 휸 휸 − 휸 휸 T tensor 𝝈풊풋 풊풋 ퟐ 풊 풋 풋 풊 A axial-vector 휸ퟓ휸풊 P pseudo-scalar 휸ퟓ  0 in non relat. limit only V & A in standard model  explains observations existence of weak currents (S, T) ? (beyond standard model) Selected topics  β-p to test weak interaction beta-neutrino angular distribution

pure Fermi transition: Vector (standard model) / Scalar (beyond SM)

different beta-neutrino angular distributions

vector scalar favors small β-ν angle favors large β-ν angle large nucleus recoil small nucleus recoil

measure β-ν angle  difficult !!! - beta-recoil angular distribution (in traps) - alternative: beta-delayed proton Selected topics  β-p to test weak interaction beta-delayed protons to test weak interaction

proton emitted from 0+ the recoiling nucleus  affects the proton peak shape Adelbergeret al., PRL 83 (1999) search for a scalar fraction 32 Ar + scalar contribution in dominating ) β(F) 0 IAS p vector

vector contribution 1993 A A (

31 Physik Z. Z.

S+p ,

32Cl

Riisager K. K.

 peak shift ,

Schardt D. D. shift measurement: higher sensitivity prev. studies: Doppler shift in β-γ 18Ne (V. Egorov et al., NP A621, 1997 14O (V. Vorobel, Eur. Phys. J A 16, 2003)  upper limit for scalar current Selected topics  β-p to test weak interaction Proton energy shift measurement: WISArD project

vector scalar B catcher e+ beam P E0 Ep E0 Ep

B P e+ beam catcher

E0 Ep E0 Ep

coll. Bordeaux, Leuven, Caen, Prague - ISOLDE proposal Selected topics  β-p to test weak interaction Challenge: energy resolution simulation

vector scalar

keV FWHM = 10 = FWHM

vector scalar

keV

, , J.G..

Blank

FWHM = 2 = FWHM B. B. Selected topics  β-p to test weak interaction WISArD at ISOLDE in the magnet of the former WITCH exp.

setup under development… Proton emission in radioactive decay experimental studies

second session Beta-delayed proton(s) emission

○ Beta-delayed 1 proton emission  Fermi transition & isospin symmetry  β-p and Gamow-Teller strength distribution  Proton emission and nuclear levels half-life ○ Beta-delayed multi-proton  Delayed 2-proton emission scheme  Experimental search for the delayed “2He” emission  Delayed multi-proton emission Beta-delayed emission  β-xp emission Beta-delayed 2-proton emission

nuclear structure: similar to β-1p… (fewer cases, less statistics)

large QEC to populate states at high enough E*  very neutron deficient nuclei (low SP & S2P)  focus on sequential versus direct 2p (or “2He”) emission

푨 푵푿풂 β+ / EC

p EC

Q 2p?

푨−ퟐ

푵+ퟏ푿풅 (+ퟐ풑) ) Xb 푨−ퟏ푿풄 (+풑) (

푵+ퟏ 2p S

푨 푵+ퟏ푿풃 Beta-delayed emission  β-xp emission  β-2p decay scheme Sequential vs. direct 2P emission

sequential emission EP1 + EP2 = const ● intermediate state EP2 ● well defined transition energies: EP1 & EP2 (+ kinematic shift: 2nd proton emitted from recoiling nucleus)

푨 푵푿풂 EP1

β+ / EC

Q E

푨−ퟐ

푵+ퟏ푿풅 (+ퟐ풑) ) Xb 푨−ퟏ푿풄 (+풑) (

푵+ퟏ 2p S

푨 푵+ퟏ푿풃 Beta-delayed emission  β-xp emission  β-2p decay scheme Sequential vs. direct 2P emission

direct 2p emission (“2He”) EP1 + EP2 = const ● not via intermediate state EP2 ● total energy (E2P) sharing: EP1  EP2 angular and energy correlations ?

푨 푵푿풂 EP1

β+ / EC

EC Q

푨−ퟐ

푵+ퟏ푿풅 (+ퟐ풑) ) Xb 푨−ퟏ푿풄 (+풑) (

푵+ퟏ 2p S

푨 푵+ퟏ푿풃 Beta-delayed emission  β-xp emission  First β-2p experiment 22Al experiment Cable et al., PRL 50 (1983), PRC 30 (1984)

EP1 + EP2 natMg(3He,xn)22Al

events with 2 protons

helium-jet technique ΔE- ΔE- E telescopes

B field to remove e+ Beta-delayed emission  β-xp emission  First β-2p experiment 22Al experiment Cable et al., PRL 50 (1983), PRC 30 (1984) 2 states populated by 2p emission

EP1+P2(x) EP1+P2(g) Beta-delayed emission  β-xp emission  First β-2p experiment 22Al experiment Cable et al., PRL 50 (1983), PRC 30 (1984) 2 states populated by 2p emission

emission via intermediate states

3 interm. states

2 interm. states Beta-delayed emission  β-xp emission  First β-2p experiment 22Al experiment Cable et al., PRL 50 (1983), PRC 30 (1984) 2 states populated by 2p emission

emission via intermediate states

2 detection config.: small & large angles  kinematic shift Beta-delayed emission  β-xp emission  Search for direct 2p emission 31Ar beta-2p decay

31Ar, the most studied case

exp. at ISOLDE:

., N.P. A (2000) A N.P. ., variation of 2nd P energy et al et

with θPP due to recoil Fynbo R small θPP

large θPP

 broadening of peak Beta-delayed emission  β-xp emission  Search for direct 2p emission beta-2He emission direct 2p emission has never been observed experimentally ● several cases: 22Al, 26P, 31Ar, 35Ca, 39Ti, 43Cr, 45Fe, … sequential emission or too low statistics ● few % of the 2P branching expected (B.A. Brown, PRL 65,1990) (for 22Al, 11.5 % expected) search for best cases  no intermediate state available 2P as only decay channel: no 1P (sequential) competition ideal, but very unlikely for candidate nuclei…

 β-2p of TZ = −3/2 nuclei (emission from IAS) 1p is isospin forbidden, 2p is allowed

light nuclei not exotic enough heavier (61Ge…)

S2P > EIAS Beta-delayed emission  β-xp emission  Search for direct 2p emission beta-2He emission: further studies search for “2He” emission signature of the emission: possible with a simple experimental set-up angular correlations: dedicated set-up

I2P few % ; I2He / I2P 1 % ; ε2P  ≥ 105 nuclei for signature  ≥ 106 nuclei for angular distribution

at ISOL facilities high granularity: direct multiplicity

efficiency: ε1P60 % ; ε2P35 % (2010) Giovinazzo J. (not uniform with θPP  simulations)

at in-flight separators 43 standard decay spectro. (impl. in silicon) Cr  no individual protons information (T1/2 = 21 ms)

 need for a TPC (energy resolution ? count rates ?) Beta-delayed emission  β-xp emission  Delayed multi-proton emission beta-delayed 3-proton emission delayed emission of 3 or more particles is possible limited interest for nuclear understanding…

few observations of β-3p emission…

45Fe 43Cr ISOLDE & Si-Cube in 31Ar (Koldste et al., PRC 2014) proj. fragmentation & TPC previously claimed (D. Bazin, 1992) but more - OTPC (Warsaw collab.) likely β-2p in 45Fe (Miernik et al., EPJA 2009) in 43Cr (Pomorski et al., PRC 2011) - TPC-CENBG in 43Cr (Audirac et al., EPJA 2012) Beta-delayed emission  β-xp emission  Delayed multi-proton emission beta-delayed 3-proton emission delayed emission of 3 or more particles is possible limited interest for nuclear understanding…

few observations of β-3p emission…

from 1p+2p+3p ISOLDE & Si-Cube from 1p+2p in 31Ar (Koldste et al., PRC 2014) previously claimed (D. Bazin, 1992) but more likely β-2p

from 1p

., Phys. Lett. B (2014) B Lett. Phys. .,

et al et Koldste Proton(s) radioactivity

S1P from NNDC

drip-line

S1P < 0 or S2P < 0 

unbound / nuclear interaction S2P from NNDC

http://www.nndc.bnl.gov/chart Proton(s) radioactivity  Particle emission at the proton drip-line Quasi-(un)bound ground state Coulomb (+ centrifugal) barrier

radius

Z isotope Z -

energy nuclear potential

(strong int.) odd

proton drip line

p energy A,Z+2p A-1,Z-1+p A-2,Z-2 Proton(s) radioactivity  Particle emission at the proton drip-line Quasi-(un)bound ground state Coulomb (+ centrifugal) barrier

radius

Z isotope Z -

energy nuclear potential

(strong int.) odd

radius

pairing effect energy D

2p energy D A,Z+2p (Z pair) A-1,Z-1+p even-Z isotope A-2,Z-2 1 proton emission forbidden (so called “true” 2P radioactivity) Proton(s) radioactivity  Particle emission at the proton drip-line 1P and 2P ground-state emitters

1P radioactivity (fusion-evaporation) no g.s. emitter below Z = 50

2P radioactivity (proj. fragment.) observed up to Z ≤ 32 expected at higher Z Proton(s) radioactivity  Particle emission at the proton drip-line 1P and 2P radioactivity

proton emission  discussed in beta-delayed emissions short nuclear lifetimes: 10−17  10−20 s.  strong interaction process time scale  not considered as radioactivity

1p & 2p radioactivity −12 Goldanskii considered a lower T1/2 limit of 10 s. limit to consider the nucleus as “thermalized” ? (10−1810−19 s ?) (lifetime >> nucleon motion time in nucleus)

upper limit defined by competition with beta decay

half-life for proton emission  Coulomb + centrifugal barrier (ground state 1p & 2p emitters)  spin isomers (1p) Proton(s) radioactivity

○ Particle emission at the proton drip-line ○ 1-proton radioactivity  Experimental studies  Probing nuclear structure ○ 2-proton radioactivity  Search for candidates  Discovery experiments  Tracking experiments Proton(s) radioactivity  1-proton radioactivity  Experimental studies Experimental discovery of proton radioactivity  1970 (V.A. Karnaukhov et. al, conf. proc.) results in contradiction with more recent work  1970: first observation from 53mCo (spin isomer: 245 ms, Jπ=19/2−, l=9) (Jackson et al., Phys. Lett. B33) reaction: 40Ca(16O,3n)53mCo proton detection in silicon ΔE-E telescope (Cerny et al., Phys. Lett. B33) confirmation with 54Fe(p,2n)53mCo  1982: ground state radioactivity of 155Lu (80.6 ms) & 147Yb (420 ms) (Hofmann et al., Zeit. Phys. A305) reaction: 92Mo + 63Cu  155Lu SHIP (@GSI) velocity filter (separator) + Si telescope (Klepper et al., Zeit. Phys. A305) reaction: 92Mo(58Ni,3n)147Yb catcher + ion source; GSI online separator (ISOL) + Si telescope  1984: short-lived emitters: 113Cs (1 µs) & 109I (> 25 µs) (Faestermann et al., Phys. Lett. B137)

about 50 known emitters today (ground- or isomeric state) Proton(s) radioactivity  1-proton radioactivity  Experimental studies Experiment @ Munich MP tamdem Faestermann et al., Phys. Lett. B137 (1984) timing detector signal drift time in TPC  p/α discrimination from track length shielded from target non interacting beam 58Ni beam (pulsed)

58Ni target Proton(s) radioactivity  1-proton radioactivity  Experimental studies Experiment @ Munich MP tamdem timing detector signal drift time in TPC  p/α discrimination from track length shielded from target non interacting beam 58Ni beam

T1/2 = 0.9 µs

58Ni target

decay curve of proton peak: - beam pulse ref. time - proton event timing Proton(s) radioactivity (S. Hofmann, EPJA 2016) about 50 known emitters today and (still…) GSI Legnaro then ANL (Argonne, US), ORNL (Oak Ridge, US),in the 1990’s PSSD + BOX setup (GSI) (Italy) and JYFL (Finland)  Daresbury (UK)  1 - proton radioactivity (ground Experimental status  Experimental studies - or isomeric state) development of experimental set (decay to excited states: “fine structure”)proton and the use of fast acquisition systems highly segmented silicon strip detectors sensitive improvements due to the use of - gamma coincidences - up

Blank & Borge, PPNP (2008) Proton(s) radioactivity

○ Particle emission at the proton drip-line ○ 1-proton radioactivity  Experimental studies  Probing nuclear structure ○ 2-proton radioactivity  Search for candidates  Discovery experiments  Tracking experiments Proton(s) radioactivity Proton emission half 1P radioactivity: a “simple” emission process tunneling process: nuclear models no preformation required (as for alpha emission) ● ● simple models (core + p): Direct probe of nuclear structure beyond the drip - -  at first order, masses at the drip WKB approximation… “frequency of assault” (almost) direct test of the  1 - proton - life single particles radioactivity T 1/2 - = line f ( A Z  , Probe for nuclear structure Q P s.p in a mean potential , L . orbitals & nuclear configuration )

QP - line Proton(s) radioactivity  1-proton radioactivity  Probe for nuclear structure Direct probe of nuclear structure beyond the drip-line exp. information vs. model calculation for L = 0

푷 푻ퟏ/ퟐ 풕풉 beta decay 2009) 푻ퟏ/ퟐ = ↔ 푻ퟏ/ퟐ 푸푷, 풍 푰푷 764 ( exp. observation condition obs.  Z dependence (Coulomb barrier)

 ang. momentum dep. Phys. Notes .

Lect Blank, Blank,

PPNP PPNP (2008) favorable energy range , , larger at higher Z Borge no observation of ground-state

emitters at low Z… Blank & & Blank Proton(s) radioactivity  1-proton radioactivity  Probe for nuclear structure Direct probe of nuclear structure beyond the drip-line exp. information vs. model calculation

푻ퟏ/ퟐ 푻푷 = ↔ 푻풕풉 푸 , 풍 ퟏ/ퟐ 푰 ퟏ/ퟐ 푷 푷 Z = 82

151 Lu decay Z = 50 g.s. emission: l = 5

 proton in h11/2

isomer: l = 2 PPNP (2008) , ,

 proton in d3/2 Borge

simple picture… & Blank Proton(s) radioactivity  1-proton radioactivity  Probe for nuclear structure Direct probe of nuclear structure beyond the drip-line

Spectroscopic factor purity of the single particle state  structure (wave functions) effects that slow the process

151 푺풕풉 calculated in more realistic approaches Lu 풕풉 푻ퟏ/ퟐ 푺풆풙풑 = 풆풙풑

푻ퟏ/ퟐ

PRC61 PRC61 (2000) , ,

comparison to probe Maglione model hypothesis

 orbitals occupancy & Ferreira 151  deformation Lu: β2 = -0.16 (expected from Möller & Nix predictions) Many studies… experimental measurements and nuclear structure interpretations (see refs. in B. Blank & M.J.G. Borge, Prog. Part. Nucl. Phys. 60, 2008) Proton(s) radioactivity  1-proton radioactivity  Probe for nuclear structure Direct probe of nuclear structure beyond the drip-line

emission for odd-Z even-N nuclei simplest case: emission of the unpaired proton: core+p description daughter Jπ = 0+ (even-even)  emitter J = L ± ½ and π = (−1)L

emission for odd-Z odd-N nuclei interaction of the unpaired proton & neutron  changes in states configurations

more than 1 unpaired proton for high spin / high exc. energy isomers: 53mCo, 54mFe, 94mAg require a more detailed structure description Proton(s) radioactivity  1-proton radioactivity Further studies

in the region 50 < Z < 82 other proton emitters could / should exist no observed case at Z = 61 (Pm) ?

no emitters in the region Z < 50

small QP window for observation  no emitters or exp. limitation (short T1/2) ? mass region accessible at fragmentation facilities  difficult with implantation-decay technique secondary reaction + detection at target (+ fast electronics) nuclear astrophysics: rp process waiting points + p (observed in β-p decay in proj. frag.) Proton(s) radioactivity

β (17Ne) 2p ?

AZ+2p A-1Z-1+p A-2Z-2 AZ+2p A-1Z-1+p A-2Z-2

after beta decay populated in reactions (discussed previously) cases with no intermediate state  only sequential decay observed 14O, 16,17Ne… no clear evidence Proton(s) radioactivity  2-proton radioactivity Two-proton emission from a nuclear state ground-state 2P emission

AZ+2p A-1Z-1+p A-2Z-2 AZ+2p A-1Z-1+p A-2Z-2

short-lived emitters long-lived emitters first obs. “simultaneous” emission  1P emission forbidden 6 12 16 45 48 54 67 light emitters: Be, O, Ne… Fe, Ni, Zn and Kr, T1/2  ms −20 19  T1/2  10 s Mg, T1/2  ps (discussed later) “democratic” decay 3-body break-up (reaction) Proton(s) radioactivity

pairing: longer isotope chains for even-Z

all even-Z nuclei at the proton drip-line are potential 2P emitters

2p energy A,Z+2p (Z pair) A-1,Z-1+p A-2,Z-2 Proton(s) radioactivity  2-proton radioactivity  Search for candidate nuclei Search for candidates 2He first predictions (V.I. Glodanskii, 1960) simple potential

barrier penetration of a 2He particle P

2 vs. simultaneous emission of 2 protons Q Q2P from mass predictions A  50 mass region (already) more favorable

confirmed by (more) recent mass predictions & local mass models (Garvey-Kelson, IMME…)

T1/2 = f(Q2P)  narrow window

Q2P too high too short T1/2 PRL(1999) decay dominates decay

Q2P too small too slow, b emission too fast + β dominates Blank, B. Proton(s) radioactivity  2-proton radioactivity  Search for candidate nuclei Search for candidates

1P-bound: Q1P < 0 and 2P-unbound: Q2P > 0 favorable case: dependence with Z due to Coulomb barrier

known ms 2P ground-state emitters

PRL (2016) (2016) PRL

, ,

et al. et

Goigoux T. T. Proton(s) radioactivity

45Fe 48Ni

PRL77 (1996)

et al. et

. Blank Blank .

PRL84 PRL84 (2000)

et al. et . Blank Blank . first observation of 45Fe B GSI experiment (1996) 3 events first observation of 48Ni GANIL experiment (1999) 4 events

no measurement of the decay modes… Proton(s) radioactivity  2-proton radioactivity  Discovery experiments β-(x)p versus 2P decay discrimination (GANIL exp.) proj. fragmentation; implantation in a 300 µm DSSSD

b P P P

2P decay EDSSD = EP1+P2 β-xp decay EDSSD = EP + ΔEβ

no β coincidence detection coincident β particle

narrow peak εP  99 % (− dead-time) degraded peak energy εβ  40 % (coinc.) + subsequent decay of 2P daughter Proton(s) radioactivity  2-proton radioactivity  Discovery experiments 45Fe decay @ GANIL / LISE identification matrix  22 events for 45Fe

58Ni beam @ 75 MeV/A natNi target (1013 pps) (240 µm)

Si-telescope (impl. in DSSSD)

LISE3 separator

(3 stages) J. Giovinazzo (2004) Giovinazzo J. Proton(s) radioactivity  2-proton radioactivity  Discovery experiments 45Fe decay @ GANIL / LISE identification matrix  22 events for 45Fe 2-proton transition

experimental information: Q2P, T1/2

 no β coincidence (>99% C.L.)

 no ΔEβ pile-up (peak 30% narrower than β- p)

 daughter decay half-life : 43Cr

J.G. et al., PRL (2002) Proton(s) radioactivity  2-proton radioactivity  Discovery experiments 45Fe decay @ GSI / FRS

beam intensity target TOF 1, 2, 3 (SEETRAM) 4 g/cm2 Be (plastic scint.)

Br1 primary beam Br DE implantation 58 Br 4 650 MeV/u Ni Br2 3 (MUSIC) degrader S1 3.2 g/cm2 Al

degrader S2 NaI barrel 3.6 g/cm2 Al 511 keV identified ions in flight identification Br  p/Z 2 }  A / Z 511 keV ToF 1,2,3  v trigger, DE Si telescope DE  Z 300 mm Si 7 x 300 mm Proton(s) radioactivity  2-proton radioactivity  Discovery experiments 45Fe decay @ GSI / FRS

Identification plot (6 events) Decay analysis β+  positron: 2511 keV annihilation γ 45Fe 2P  γ anti-coincidence

M. Pfützner et al. (EPJA 2002) Z

2P decay: 4 events

A/Z

+ퟑ.ퟒ 푻ퟏ/ퟐ = ퟑ. ퟒ−ퟏ.ퟏ 풎풔 0 0 1 2 3 4 5 6 푸 = ퟏ. ퟏ ± ퟎ. ퟏ 푴풆푽 energy (MeV) ퟐ푷

Good agreement with GANIL experiment for Q2P and T1/2 Proton(s) radioactivity  2-proton radioactivity  Discovery experiments similar experiments

54Zn peak: +ퟏ.ퟖ 푻ퟏ/ퟐ = ퟑ. ퟐ−ퟎ.ퟖ 풎풔 daughter (52Ni): 푻ퟏ/ퟐ = ퟑퟎ ± ퟐퟎ 풎풔 (C. Dossat, PhD: 39.9  0.7 ms) Blank et al. (PRL 2005)  2-proton emitter !

48 Ni – 2P ? 3 decay events: T1/2 ~ 1-2 ms – second decay ○ 2 are compatible with β-delayed particle emission (β coinc. and high part. energy) ○ 1 is compatible with 2-proton decay  not enough to conclude… Dossat et al. (PRC 2005) Proton(s) radioactivity  2-proton radioactivity  Discovery experiments last identified emitter: 67Kr

BigRIPS (+ZDS) 78Kr beam campaign (2015): 350 MeV/A – 250 pnA setting on 65Br (between 63Se & 67Kr): about 5 days

observed production BigRIPS (F7) ZDS (F11) WAS3ABI 59Ge 1170 979 563 63Se 336 258 193 67Kr 80 79 49

B. Blank et al. (PRC 2016) Proton(s) radioactivity  2-proton radioactivity  Discovery experiments last identified emitter: 67Kr

T1/2 = 7.4 ± 3.0 ms observed peak: 9 events T. Goigoux et al. (PRL 2016) Q2P = 1.69 ± 0.02 MeV

no beta coincidence

εβ = 67 % prob. to miss all  510-6

no annihilation 511 keV

all events εγ  8 % events with β coincidence prob. to miss all  45 %

Q2P = 1.69 ± 0.02 MeV T1/2 = 7.4 ± 3.0 ms BR2P = 37 ± 14 % Proton(s) radioactivity  2-proton radioactivity  Discovery experiments

Indirect measurements (long lived emitters)

in the 60’s first predictions by Goldanskii late 90’s candidates can be produced at fragmentation facilities (discovery of 45Fe, 48Ni) Discovery experiments indirect measurements: global quantities only 2002 2-proton radioactivity of 45Fe at GANIL & GSI 2004 2-proton radioactivity of 54Zn (GANIL) indication of a possible 2P-decay for 48Ni (1 event) 2016 2-proton radioactivity of 67Kr (RIKEN)

indirect evidence  no individual observation of the emitted particles

experimental information:

 only global quantities: Q2P , T1/2 and B.R.  limited theoretical interpretation

(1 information, since Q2P is an input for calculations) Proton(s) radioactivity  2-proton radioactivity  Discovery experiments

Indirect measurements

L.V. Grigorenko: emission dynamics B.A. Brown: nuclear structure half-lives: 2-proton amplitudes: 2 2 2 2 2 2 T1/2 for pure (s ,) p and f config. for pure (s ,) p and f config

“Shell model corrected half-lives” 2 2 A = A(f ) + A (p ) T1/2(2P) calculation experiment(s) 45Fe ퟐ. ퟕ ms ퟑ, ퟕퟔ ± ퟎ, ퟐퟔ ms OK

54 +ퟎ.ퟕퟑ Zn ퟏ. ퟔ ms ퟏ. ퟗퟖ−ퟎ.ퟒퟏ ms OK 67Kr ퟔퟔퟎ ms ퟐퟏ ± ퟏퟐ ms !? Lower life-time for 3-body model: 240 ms (pure p2 configuration) Proton(s) radioactivity

Proton-proton correlations: 3-body model

. C C . (2003)

Rev

, Phys. , Phys.

Grigorenko L.V. L.V.

prediction of distributions for - energy sharing between protons - proton-proton angular correlations

emission kinematics sensitive to the emitter structure Proton(s) radioactivity nuclei produced only at fragmentation facilities

J. Giovinazzo (2009)   need to“see”need protonsthe stopperthe in implantedstoppera thick in emitting emitting nucleus  2 Proton - proton radioactivity - proton correlations measurement ion ion  Tracking experiments identification and tracking use of an active gas stopper: TPC Proton(s) radioactivity nuclei produced only at fragmentation facilities

J. Giovinazzo (2009)   need to“see”need protonsthe stopperthe in implantedstoppera thick in  2 Proton - proton protons radioactivity - proton correlations measurement  Tracking experiments use of an active gas stopper: the the the the todrift a2Ddetector ionisation electrons down in slowcharged particles 3 drift time tracksprojection 2D detector rd dimension the gasvolume measures registers TPC Proton(s) radioactivity  2-proton radioactivity  Tracking experiments TPCs for 2-proton radioactivity studies

drift volume (gas)

(uniform electric field) elect. field elect.

collection plane (charge collection)

signal readout (amplitude and time) Proton(s) radioactivity  2-proton radioactivity  Tracking experiments TPCs for 2-proton radioactivity studies active volume gaz: P10, 0.5 or 1.0 bar CENBG TPC

drift electrodes drift volume (gas) GEMs (uniform electric field) strips

collection plane 2D strip collection (charge collection) GEMs amplification gain x10 / GEM  sensitivity  resolution signal readout electronics (amplitude and time)

2 x 384 channels Energy & Time 1.3 ms dead time Proton(s) radioactivity  2-proton radioactivity  Tracking experiments TPCs for 2-proton radioactivity studies

Warsaw Optical-TPC active volume drift volume (gas) amplification and (uniform electric field) conversion (electrons to light) collection plane CCD camera (charge collection)

, et al., et , 2007 cumulated light full 2D projection

Miermik signal readout , K. K. , (amplitude and time)

Pfützner Photomultiplier

M. M. with sampling ADC  time distribution of total signal Proton(s) radioactivity  2-proton radioactivity  Tracking experiments Direct observation of 2-proton radioactivity

45 Fe 54Zn 7 p-p events only first 2P tracks (GANIL)

(GANIL)

., ., 2011 PRL

et et

l., PRL 2007 PRL l.,

Ascher

et a et P. P.

J.G. J.G. 48Ni established as 2P emitter 4 p-p events experiment @ NSCL 45Fe 48Ni

 75 counts of p-p 2p ., PRL PRL ., 2011

correlations ., 2007 PRL

et et

Miernik

Pomorski

K. K. M. M. Proton(s) radioactivity  2-proton radioactivity  Tracking experiments Probing nuclear structure first angular distribution: good agreement with predictions from the 3-body model

p-p angle energy

sharing

(MSU)

Fe Fe

et al. al. 2007) (PRL et

Miernik K. K.

pioneering experiments 7 events…

 opening structure studies at the drip-line

 angular distribution probes the wave (GANIL)

function content (single particle states) Zn

et al., 2010 al., et 54

requires more statistics Ascher other cases to test the models descriptions P. Proton(s) radioactivity

45Fe : Z = 26 54Zn : Z = 30 2p 2p 1f 1f 7/2 3/2 5/2 1/2 2p 2p 1f 1f 7/2 5/2 3/2 1/2  2 - proton radioactivity Probing nuclear structure proton   푾 푾 Tracking experiments orbitals configuration - proton angular distribution 풑 풑 ퟐ ퟐ = = ퟐퟒ% ퟑퟎ − + ퟐퟏ ퟑퟑ % 45 Fe 54 Zn

P. Ascher et al., PRL (2011) K. Miernik et al., EPJA (2009) Proton(s) radioactivity

48Ni : Z = 28 45Fe : Z = 26 67Kr : Z = 36 54Zn : Z = 30 2p 2p 2p 2p 1f 1f 1f 1f 7/2 3/2 5/2 1/2 7/2 5/2 3/2 1/2 2p 2p 2p 2p 1g 1f 1f 1f 1f 7/2 5/2 7/2 5/2 3/2 1/2 3/2 1/2 9/2  2 - proton radioactivity Probing nuclear structure proton   푾 푾 Tracking experiments orbitals configuration - calculation: 67 doubly magic 48 proton angular distribution 풑 풑 Kr ?? Ni ?? ퟐ ퟐ   = = mixed direct sequential/ emission ? deformation ? ퟐퟒ% ퟑퟎ − + ퟐퟏ ퟑퟑ ( p % 3/2  ) pure configuration ? 2 configuration ? 45 Fe 54 Zn

P. Ascher et al., PRL (2011) K. Miernik et al., EPJA (2009) Proton(s) radioactivity (1) improveexperimental information ofknownemitters    48 54 67 Kr Ni Zn : : : energydistribution… sharing differentdecay pattern? (sequential) exp. atRIKEN (J.G. requireimprovements of identificationtoseparator increase acceptance statisticslimited expected( exp. magic) at(J.G.(doubly GANIL experimentat O acceptedRIKEN with 

J. Giovinazzo 2 - proton (for tech. dev.: Further studies for 2P radioactivity radioactivity 48 Ni & etal 67 ACTAR TPC Kr  .): exp.) Tracking experiments  20 counts) et al - TPC (M. TPC (M. 0 .) seq. Pfützner 2P 0.5 et al E .) P1 / mix. Q 2P 1 Proton(s) radioactivity  2-proton radioactivity  Tracking experiments Further studies for 2P radioactivity (1) improve experimental information of known emitters

(2) search for new candidates up to Z  50 (Tin) production at FAIR / SuperFRS known emitters search for new TPC emitters ? exp. Proton(s) radioactivity  2-proton radioactivity  Tracking experiments Further studies for 2P radioactivity (1) improve experimental information of known emitters

(2) search for new candidates up to Z  50 (Tin) production at FAIR / SuperFRS known emitters search for new TPC emitters ? exp.

(3) consolidate and improve theoretical interpretations for a combined nuclear structure and emission dynamics Proton(s) radioactivity  2-proton radioactivity  Tracking experiments 19Mg: a short-lived 2P emitter secondary reaction production (GSI/FRS) protons tracking

p 24 20 19 17

Mg fragment Mg Mg p Ne 2007 PRL ., .,

separator (FRS) al et et

primary Mukha

target (Be) I. fragments recoil identification secondary identification target (Be) Proton(s) radioactivity  2-proton radioactivity  Tracking experiments 19Mg: a short-lived 2P emitter secondary reaction production (GSI/FRS) protons tracking

PRL 2007 PRL p ., ., 19 17

al 20Mg Mg p Ne

et et

Mukha I. I.

recoil 17Ne+p+p events kinematics reconstruction  from vertex position: ● fast emission of excited states ● delayed decay of ground state:

T1/2 = 4.0 ± 1.5 ps Proton(s) radioactivity  2-proton radioactivity  Tracking experiments 19Mg: a short-lived 2P emitter

secondary reaction production (GSI/FRS)

PRC 2008 PRC

PRL 2007 PRL

., .,

et et

Mukha

I. I. I. I.

17Ne+p+p events kinematics reconstruction  from vertex position: ● fast emission of excited states ● delayed decay of ground state:

T1/2 = 4.0 ± 1.5 ps

 p-p angles reconstruction good agreement with 3-body model Proton(s) radioactivity  2-proton radioactivity Physics of two-proton radioactivity

ground-state 2-proton radioactivity  drip-line and masses (beyond the « drip-line ») transition Q-values radius  nuclear structure

energies, half-life, energy levels configuration  pairing correlations in energy and angle of emitted protons  tunnel effect theoretical descriptions

the emitted protons carry information on what’s going on inside the nucleus the 2-proton radioactivity mixes the structure (wave functions) and the (decay) dynamics Additional selected topics

○ Delayed proton emission to test weak interaction ○ ACTAR TPC Selected topics  ACTAR TPC time projection chambers for (fundamental) nuclear physics

development of a new TPC (GANIL and coll.) pads (hex): 2D proj. for a large (nuclear) physics case nuclear wires: drift time reactions

CENBG TPC X-Y strips ions stopping energy & time: and decay 2x 1D proj. GANIL, CENBG, IPNO (F) Leuven (B), Santiago de C. (S) Optical TPC (Warsaw) CCD cam.: 2D proj. PM + sampling: ions stopping global time dist.

and decay image Warsaw coll. Warsaw image Selected topics  ACTAR TPC Full 3D + charge reconstruction

pads plane TPC principle time sampling (signal collection) of signal 2D digitization z  t 3D digitization

DE(x,y,z)  DE[xi,yj](z)  DE[xi,yj](t)  DE[xi,yj,tk]

particle gas J. Giovinazzo (2013) Giovinazzo J. track ionization

ionization time samplingtime drift 3D reconstruction of of collected signalcollected of (velocity,, ionizations charges along

dispersion) the particles trajectories

pad signal

pads plane

(signal collection) (2013) Giovinazzo J. GET electronics

to dem.

to phys. Selected topics “ “ decay reaction short transverseshort tracks, larger implantation depth 256x64 pads collection plane large transversetracks 128x128pads collection plane ” chamber ” ” chamber ” 

image R. Raabe ACTAR TPC

image R. Raabe 1 development, 2 chambers shared design and technologyshared and design GET electronics geometries2 2x2 16384 pads,   forreadout channels technicalsolution (J. R&D plane pad decayRegion chamber: (J.F. ERC funding: main Giovinazzo Grinyer , GANIL), , CENBG) , mm 2 Selected topics  ACTAR TPC IRFU, CENBG, Dedicated electronics GANIL, MSU ANR 2011-2015

detector TPC AGET chip AsAd board CoBo module MuTAnT control / acquisition 16384 pads 64 channels 4 AsAd boards clock distrib., signal processing 4 chips (+ config.) digital data trigger management (CSA + shaper), management (3 levels) analog memory, signal & mult. discriminator coding (ADC)

channel processing (AGET)

V (t) reconstruction q(t) C A(t) A(t) procedure needed Selected topics  ACTAR TPC input signal: charge distribution input charge distribution depends on tracks

but… charge distribution information is “washed out” by AGET shaping reconstruction principle: deconvolution from AGET response function

detector output GET input (data)

reconstr. signal ? to dem.

to phys. Selected topics  ACTAR TPC Empirical response function

response function estimate from input pulser  AsAd pulser (with FPN channels  input signal)  external pulser 푶풖풕 풌 de-convolution in Fourier space (use of FFT): 푯 풌 = 푰풏 풌

residual noise  need for filtering  low-pass filter: [풌] 푺풋 푰 [풌] = ⋅ 횽 풌 풋 [풌] 푯풋 single event (square input) Selected topics  ACTAR TPC Reconstruction characterization

various width square signals  reconstruction fidelity difference between reconstructed and input signal

 reconstruction resolution separation of 2 point charges

 timing precision

separation of 2 charge deposits results are a compromise between noise and precision Selected topics  ACTAR TPC ACTAR TPC demonstrators 2 demonstrators: @ GANIL  tested in-beam (2015), electronics issues… @ CENBG  new pad plane techno, tested with sources (2016)

readout drift cage (GANIL) FAKIR pad plane electronics

flex. connectors

chamber

gas control & ZAP (flex.) control data acquis. Selected topics

web image H. Ponting  ACTAR TPC “FAKIR” pad plane demonstrator pad plane final detector Selected topics  ACTAR TPC Detector characterization

pad plane ● Energy resolution

● Tracks reconstruction quality source active volume

single track: alpha particle, 45° angle 3D track

X-Y energy deposit: Bragg peak

P10 gas (Ar-CH4), 400 mbar Selected topics  ACTAR TPC Energy resolution

triple alpha source: 5-6 MeV effective FWHM: 130 keV  good resolution for a gas detector (silicon  25 keV)

X-ray source (55Fe): 5.9 keV

conversion electron keV

keV FWHM: 20 %

2.7 5.9 Selected topics  ACTAR TPC Tracks reconstruction

tracks length (end point) vdrift too large  Bragg peak fitting

 signal dispersion along drift vdrift too small

drift velocity

ퟐ ퟐ ퟐ 푳 = ∆푿 + ∆풀 + 풗풅풓풊풇풕 ∙ ∆푻

track length precision

 simple line trajectory σL = f(vdrift)

 σL  3.2 mm (σL / L  3%)

equiv. to dispersion of alpha in the gas…  intrinsic resol. < 1 mm Selected topics  ACTAR TPC ACTAR TPC physics program

● Reaction studies (transfer, inelastic scattering…) ● Nuclear structure

● Decay studies (for fragmentation experiments)  beta-delayed proton decay for astrophysics

 proton radioactivity

 2-proton radioactivity Selected topics  ACTAR TPC Decay studies with ACTAR TPC

beta-delayed proton decay for astrophysics

decay spectroscopy is an access to:

- resonances around SP populated in p-capture process - competition with γ de-excitation - …

ex.: nucleosynthesis in novae  22Na(p,γ)23Mg reaction 23 23  Mg states around SP: β-p of Al

difficulty: low energy protons: 200 keV  2 MeV in thick DSSSD: beta background

A. Saastamoinen et al. PRC 83, 045808 (2011) E.C. Pollacco et al. NIM A 723, 102 (2013) Selected topics  ACTAR TPC Decay studies with ACTAR TPC

beta-delayed proton decay for astrophysics 46Mn β-p decay several cases:

nucleosynthesis in novae (2007) A792 NP , 23 22 23

Al decay  Na(p,γ) Mg .Dossat 31Cl decay  30P(p,γ)31S C

X-ray bursts 20Mg decay  19Ne(p,γ)20Na

ex. (proposal A.M. Sanchez-Benitez / F. de Oliveira): 46Mn decay: spectro. of 46Cr ? ?  rate of 45V(p,γ)46Cr

(production of 44Ti in SN-II)

(2016) J.G. J.G. TPC  reduction of β background Selected topics expectedother proton branches (gammaonly) previousRISING campaign proton radioactivity: decayof possible (not probabilitysame expected for  E P = 1.3 = 1.3 deduced observed  MeV 2p ACTAR TPC branch(low BRexpected) from transition ) γ - active gas γ volume coinc Decay studies with ACTAR TPC . 54m E very short half very P Ni = 2.6    (10 for P10@ 1atm: fromidentified tracks with protons + MeV ) implantation - (1 life - 2 MeV ) L L signal come ( ( 2.6 1.3 out of ionsignal MeV MeV (  GeV ) )   ) 12 4 cm cm

E690: D. Rudolph et al. Selected topics  ACTAR TPC Decay studies with ACTAR TPC 2-proton radioactivity: proton-proton angular and energy correlations

decay of 48Ni, 54Zn, 67Kr… and higher Z ? J. Giovinazzo (2013) Giovinazzo J. Selected topics  ACTAR TPC Decay studies with ACTAR TPC 2-proton radioactivity: proton-proton angular and energy correlations

decay of 48Ni, 54Zn, 67Kr… and higher Z ? J. Giovinazzo (2013) Giovinazzo J. The End !

thank you for you attention