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What is the relationship with ? What is ALTO ? What is (currently) and what is expected to be (in a near future) the physics output of the facility ? ?

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Presentation on theme: "What is the relationship with ? What is ALTO ? What is (currently) and what is expected to be (in a near future) the physics output of the facility ? ?"— Presentation transcript:

1 What is the relationship with ? What is ALTO ? What is (currently) and what is expected to be (in a near future) the physics output of the facility ? ? ? Atelier ESNT 4-6/02/08 lOrme des Merisiers A few elements on how to produce exotic nuclei (a pedestrian approach) ? Physics at ALTO ALTO in the context of the construction of SPIRAL2 Atelier ESNT 4-6/02/08 lOrme des Merisiers

2 Recent history (80s – 00s) of the experimental research on exotic nuclei in France (especially structure) Terra incognita of the medium mass n-rich nuclei Fragmentation of intense stable ion beams 1- General context SPIRAL 1

3 Fission was understood as being probably the best nuclear reaction to be used for the production of medium mass n-rich nuclei 1- General context

4 from P.W.Lisowski et al, OECD/NEA Report NEANDC-305 'U' 1991 p.177 Thesis Nicolas Pauwels IPN Orsay Production of fission fragments by photo-fission Production of fission fragments using fast neutrons

5 2. Fusion reaction with n-rich beams 1. Fission products (with converter) 4. N=Z Isol+In-flight 5. Transfermiums In-flight 3. Fission products (without converter) Primary beams: deuterons heavy ions 7. High Intensity Light RIB 6. SHE 8. Deep Inelastic Reactions with RNB Regions of the chart of the nuclei accessible with SPIRAL2 beams

6 2- How to produce exotic nuclei 1 Choose the good reaction mechanism At ALTO : fission (and nothing else) 2 Choose the production method 1983 Neutron rich Neutron deficient Thanks to the S3 project

7 2 cyclotrons CSS1 and CSS2 Heavy ions AMeV (so called intermediate energy) Electrons 10 µA 50 MeV LINAG : light ion beam high intensity (few mA !) see Stéphane 2- How to produce exotic nuclei Isotopic Separation On Line

8 thermalization Reaction products are fully stopped inside the target and neutreulized No thermalization Ex : SISSI target, production target at LISE etc Ex : Christmas tree shaped like target at SPIRAL1-GANIL 2- How to produce exotic nuclei

9 The fission target : 72g of uranium carbide heated at 2200°C for the release of the elements. Total length 19 cm Typical design of a target

10 Production of fission fragments by photo-fission at alto Incident electron beam 50 MeV 10 µA Photon flux target fission

11 At ALTO : Carburation room, dimensioned for SPIRAL2 targets Tests of target ion sources for ISOLDE, SPIRAL2 and EURISOL at ALTO Collaboration with Argonne for dense uranium carbide R&D studies for

12 Prototype in steel to test mechanical rigidity and temperature distribution validation of simulations Ta prototype under tests of long term heating R&D studies for Design of the oven

13 2- How to produce exotic nuclei The target-ion source ensemble : le nerf de la guerre Carburization at 1600°C UC+UC 2 +C 2200°C UC 2 + C 2000°C UC 2 + C UO 2 grain (~20 m) + C grain(~44 m) Before carburization (C/U = 6) Heating time ~ 10h The microscopic structure of the target plays a fondamental role for the release of the elements Electronic microscope X-ray spectroscopy Ni Z=28 Sr Z=38 Pd Z=46 Prohibiting release times Target : limiting factor = release time of the elements

14 Taken from PIAFE project Report based on Studsvik measurements Calculations from M.-G. Saint-Laurent 2- How to produce exotic nuclei

15 separation Reaction products are fully stopped inside the target and neutralized identification Ex : LISE, SPEG, VAMOS The PARRNe mass separator 2- How to produce exotic nuclei

16 detection Reaction products are fully stopped inside the target and neutralized Ex : EXOGAM Detection system 2- How to produce exotic nuclei Detection system Ex : Ge detector array : OSCAR (the Orsay Segmented lover Array)

17 The target-ion source ensemble : le nerf de la guerre Ion source : limiting factor = Z dependence 2- How to produce exotic nuclei Laser ion source (quasi exclusive in Z) Surface ion source (limited to alkali and alkali like) Hot plasma (Z « universal ») High temperature (1900 °C) Compact: the target is part of the source high efficiency well adapted for a large number of elements No selectivity

18 Does it work ? Measured effective yields June 2006 I e =100 nA (instead of 10 µA nominal)

19 2- How to produce exotic nuclei Where do the R&D efforts should apply ? 2 main R&D axes Release of the elements High density U carbide (SPIRAL 2) Release using molecules Microscopic studies ( ISOLDE collaboration) Selectivity of the elements Chemical selectivity Selectivity using lasers combinaison trap +laser bunch of the beam Magnetic selectivity optimization of the production -Selectivity -Release Accelerator (driver) Reaction (fission) Nbr of Atoms in target Intensity of the signal Detection system

20 Used as such (good optical quality) 2- How to produce exotic nuclei Summary : ISOL technique, key features Incidentally : why do we (experimentalists) us it ? ISOL The key aspect : The radioactive nuclei are available as an ion source This is THE method which allows to produce the largest amount of radioactive nuclei per unit of time The radioactive nuclei are created in an experimental environment similar to the traditional stable ion sources keV 1 2 Injection into an accelerator Secondary reactions Coulomb excitation (ex REX ISOLDE) Direct reaction (ex SPIRAL1 GANIL) approx 10 AMEV Few AMEV AMEV Fragmentation Future ?

21 photofission fast neutrons >10 15 protons Fissions/sec How does ALTO compare to the major fission based ISOL projects ?

22 A=132 CsXeITeSbSnIn Comparison with ISOLDE/CERN ALTO = ISOLDE with less isobaric contaminants ! (for fission products only)

23 2bis- ALTO : tour du propriétaire Where is it ?

24 2bis- ALTO : tour du propriétaire 1/3 ISOL 1/3 Stable beams 1/3 Agregats General layout

25 Radioactivité : dérouleur de bande; géométrie rapprochée SPLIT POLE BACCHUS ligne 420 ligne « basse énergie » lignes ions stables équipées dun spectromètre lignes ions stables non équipées dun spectromètre ligne 410 (ré-ouverture en 2008) OSCAR (Orsay Segmented Clover Array) ORGAM phase1 (ORsay GAMma array) 2bis- ALTO : tour du propriétaire

26 fissions /s The ISOL facility Electron driver Target ion source ensemble PARRNe mass separator Lines towards experiments

27 The electron driver the LEP injector arriving from CERN-Geneva The LEP injector installed 2bis- ALTO : tour du propriétaire

28 The output of LEP injector and deviation 2bis- ALTO : tour du propriétaire

29 From the deviation to the target-ion source ensemble 2bis- ALTO : tour du propriétaire

30 The electron driver 2bis- ALTO : tour du propriétaire

31 4 Plastic Scintillator OSCAR: Orsay Segmented Clover Array -Ring : 4 segmented 6cm ~ 10% efficiency Conversion electron detector Neutron detector 3He 2bis- ALTO : tour du propriétaire

32 3- Physics at ALTO What we currently do Structure of medium mass neutron rich nuclei Our spécialité : evolution of the N=50 shell effect towards 78Ni Measurement of the evolution of mean square charge radius strength functions n 2n decay measurements (P n, P 2n, T 1/2 ) g factor measurements Fast timing measurements Structure of medium mass neutron rich nuclei : evolution of the N=82 shell effect, search for exotic shell effects eg HO magic shell effects ray spectroscopy Laser spectroscopy Immediate thematic extension with the existing instruments T1/2 (ps range) feasable within 2 to 3 years

33 3- Physics at ALTO Which nuclei ? Observable Experimental technique Physics case Synopsis Energy level pattern spectroscopy following -decay Static moments :Q, Laser spectroscopy Exploration of the valence space extending N-E to 78Ni Evolution of the N=50 and N=82 shell effects far from stability Onset of the collectivity and nature of the correlations T1/2 of the excitation levels->dynamic moments :B(M1) (E2) Fast timing Polarization effects Pn P2n and T1/2 Neutron detection Nature of the em transitions Electron conversion g-factor and spin Nuclear orientation Many purpose (including systematics)

34 LE LION ET LE RAT Il faut, autant quon peut, obliger tout le monde On a souvent besoin dun plus petit que soi. De cette vérité deux fables feront foi, Tant la chose en preuves abonde. Entre les pattes dun lion Un rat sortit de terre assez à létourdie. Le roi des animaux, en cette occasion, Montra ce quil était et lui donna la vie. Ce bienfait ne fut pas perdu. Quelquun aurait-il jamais cru Quun lion dun rat eût affaire ? Cependant il avint quau sortir des forêts Ce lion fut pris dans des rets, Dont ses rugissements ne le purent défaire. Sire rat accourut, et fit tant par ses dents Quune maille rongée emporta tout louvrage Patience et longueur de temps Font plus que force ni que rage. Jean de La Fontaine, Fables, Livre II, 11 Based on a tale from Esope (VII-VI BC) Technical issues and administrative traps Atelier ESNT 4-6/02/08 lOrme des Merisiers


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