100 m down and light-years away: Nuclear science in an extreme laboratory

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100 m down and light-years away: Nuclear science in an extreme laboratory Z. Gosser, M.J. Rudolph, K. Brown, B. Floyd, T. Steinbach, S. Hudan, and R.T. de Souza GANIL : A. Chbihi, B.

1 100 m down and light-years away: Nuclear science in an extreme laboratory Z. Gosser, M.J. Rudolph, K. Brown, B. Floyd, T. Steinbach, S. Hudan, and R.T. de Souza GANIL : A. Chbihi, B. Jacquot ORNL : J.F. Liang, D. Shapira WMU: M. Famiano We gratefully acknowledge the support of the US Dept. of Energy under Grant No. DEFG02-88ER-40404

2 Origin of the elements Only elements Z=1-4 produced in the Big Bang Fundamentals of supernova explosions are not understood! Synthesis of the heavy elements is not understood Limits of nuclear stability (superheavy elements, N/Z exotic) poorly known Existing and next generation radioactive beam facilities allow us to probe these questions H Li Be H _"Young St ars" "Mature Stars" Li Be B C N O F Ne H Li Be Na Mg _"Old St ars" _Synthesis of the Elements He He He B C N O F Ne Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu _NGC 3603 _NGC 3603 Prestellar H Clouds SPIRAL GANIL (France) RIKEN (Japan) Michigan State (ReA3, FRIB) GSI-FAIR (Darmstadt, Germany) Texas A&M _Supernova Remnant H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Rf Db Sg Bh Hs Mt Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Cassiopeia A

3 Bloomington area 18,000 years ago! Where I am from

4 Bloomington now!

5 Where I am from

6 DEPARTMENT OF CHEMISTRY SIMON HALL Multidisciplinary Science Building

7 IU Department of Chemistry 35 research faculty in all major disciplines of chemistry (analytical, biochem, inorganic, organic, and physical) Dedicated support scientists and staff (NMR, mass spec, glass blowing, mechanical instruments, electronics, information technology) and the life blood of any graduate department energetic, bright graduate students.

Center for Exploration of Energy and Matter (CEEM) CEEM is a multidisciplinary laboratory performing research and development in the areas of accelerator physics, nuclear science, materials science,

8 Center for Exploration of Energy and Matter (CEEM) CEEM is a multidisciplinary laboratory performing research and development in the areas of accelerator physics, nuclear science, materials science, life science and biomedical applications of accelerators. Accelerator Physics Defining the physics of producing and handling beams of sub-atomic particles Biomedical and Life Sciences Harnessing the power of radiation for research in biology and medicine Materials Research Imaging, modeling and manipulating macromolecules Neutron Physics Using neutrons to explore the molecular structure of proteins, crystals, surfaces, and much more Nuclear Physics and Chemistry Probing matter and forces at the sub-atomic scale

9 Where we do our experiments Argonne National Lab. NSCL Michigan State Univ. Notre Dame Nuclear Science Lab. GANIL, France GSI, Germany TAMU Cyclotron Facility Oakridge National Laboratory

Astrophysics : Neutron star crusts (pycnonuclear fusion, X-ray superbursts) 2.

10 100 m down and light-years away: Nuclear science in an extreme laboratory Indiana University, ORNL, Western Michigan University, GANIL 1. Astrophysics : Neutron star crusts (pycnonuclear fusion, X-ray superbursts) 2. Nuclear Physics: Structure of neutron-rich nuclei and fusion dynamics DATA SCARCE Thermonuclear fusion vs pycnonuclear fusion

11 Experimental observations : X-ray bursters vs Superbursters Superbursts are thought to arise from the ignition of the ashes of bursts i.e. fusion of carbon. Superburst Problem: At the temperature of the crust, the Coulomb barrier is too high for thermonuclear fusion of carbon another heat source is needed.

C.J. Horowitz, H. Dussan, and D.K. Berry Phys. Rev C77, 045807 (2008) Y. Eyal et al.

Astrophysically relevant regime 1. Extrapolation necessary both in neutron number (N) and energy (independent)! 2.

12 C.J. Horowitz, H. Dussan, and D.K. Berry Phys. Rev C77, (2008) Y. Eyal et al., PRC 13, 1527 (1976) Dussan, Horowitz S(E) is directly related to σ(e). Measure σ(e) know S(E). Astrophysically relevant regime 1. Extrapolation necessary both in neutron number (N) and energy (independent)! 2. At 5 x 10 8 K Gamow peak ~ 3.1 MeV for 24 O + 24 O and ~ 2.7 MeV for 16 O + 16 O 3. 1/e width of Gamow peak ~ 1 MeV. Polarization of nuclei fusion enhancement?

13 For neutron rich oxygen, does energy dependence follow simple barrier penetration like 16 O+ 12 C or is there an enhancement as in 9 Li + 70 Zn? For light systems near β stability : Simple barrier penetration with Woods Saxon density distributions is reasonable near and above the Coulomb barrier Dussan, Horowitz Loveland et al, PRC (2006) Increase due to dynamics of neutron-rich skin? Measure to lowest energy possible ( 7 MeV) ; develop technique Extend measurement to 5-6 MeV

14 Ideal systems: 24 O + 24 O and 28 Ne + 28 Ne In 2008, 20 O was possible at GANIL s SPIRAL facility with an intensity of 1x 10 4 pps. Choose 20 O + 12 C for a first measurement Challenges: Can a contaminant free beam of 20 O be delivered? Minimum energy of beam is 3 MeV/A i.e. beam will have to be degraded Beam also needs to be degraded because time to retune cyclotron for each energy ~8hrs making excitation function unfeasible

15 To access the relevant region we need E lab /A = 1 to 2 MeV for the neutron-rich oxygen beam. 20 O + 12 C 32 Si* (E* ~ 50 MeV) 32 Si* 29 Si + 3n 32 Si* 29 Al + p + 2n 32 Si* 26 Mg + + 2n

16 Estimate of statistics Y. Eyal et al., PRC 13, 1527 (1976) Count rate based on Eyal cross-sections; I = 1x10 4 p/s ( 20 O) and t= 100 g/cm 2 Expt. Approved for ~7 days running time! Entire range spanned by Eyal is measured with comparable statistics!

Experimental Setup of E575S BEAM 20 O CID Active Gas degrader cell ~8 cm long, 25 mm aperture 20 O + 12 C 32 Si* (E* ~ 50 MeV) 12 2 cm C 60 cm tgt Degrade in active gas cell to efficiently change

17 Experimental Setup of E575S BEAM 20 O CID Active Gas degrader cell ~8 cm long, 25 mm aperture 20 O + 12 C 32 Si* (E* ~ 50 MeV) 12 2 cm C 60 cm tgt Degrade in active gas cell to efficiently change energy for excitation function. Measure velocity after degrading (TOF) : E/E = 200 kev/20 MeV Evaporation residues (ER) detected in Si detectors (angular distribution) SBD S2: S1: MCP18 t 250 ps P chamber ~ 1 x 10-6 torr (w/o cryo) ZDIC: 3.1 ZDIC MCP40 48 rings and 16 pies

Stage 1: Active degrader -- Multi-anode ionization chamber Also useful for

parallel plate design with Frisch grid thin window design with support

8 cm long (6 anodes) CF 4 gas : P = 30 200 torr ( using 90 180 mbar in

18 Stage 1: Active degrader -- Multi-anode ionization chamber Also useful for tagging/rejecting beam contaminants (e.g. fluorine) from 20 O beam standard parallel plate design with Frisch grid thin window design with support wires for minimal bowing active region 8.8 cm long (6 anodes) CF 4 gas : P = torr ( using mbar in experiment) E deposit = 8-40 MeV Need to characterize det. performance Measure magnitude of divergence/multiple scattering

19 Stage 2: MCPs for start signal of TOF Microchannel plate detectors 10 cm Alpha source MCP1 MCP2 TOF of 6 ns correct for 5 MeV Time resolution of 300 ps (w/o optimization)

residues are distinguished on the basis of energy alone.

20 Stage 3: Separating evaporation residues from elastic 20 O Calculations based on assumption of fusion evaporation (PACE) and Rutherford scattering (LISE++) At higher energies, in principle, residues are distinguished on the basis of energy alone. At lower incident energies, residues are distinguished on the basis of both energy and TOF. A time resolution of 1ns is necessary.

21 Stage 3: Residue detection : Annular segmented Si detectors Annular Si det. From Micron Semiconductor 16 pies ( ) on ohmic side either 48 (S2) or 16 (S1) rings ( ) junction side Good angular resolution: 0.17 for Good energy resolution 70 mm Si det. Pie (x48) Cap. splitter Slow CSA Shaper Pk. ADC NEW! Fast Timing Pickoff LE discriminator TDC

Beam test: Hope College Apr. 09 (Thanks to G.

8 MeV (elastically scattered from a Cu foil)

amplifier Simultaneous measurement of slow

22 Beam test: Hope College Apr. 09 (Thanks to G. Peaslee and P. deyoung) 16 O at 6.8 MeV (elastically scattered from a Cu foil) Rise time : 7 8 ns for oxygen same as 6 MeV particles. 64 channels slow preamp 16 channels of fast amplifier Simultaneous measurement of slow signals good energy resolution 0.5 %. Can trigger at E deposit = 0.5 MeV Slow signal after shaping amplifier

226 Ra α source Microchannel plate start det. S2 silicon stop det. Time-of-flight for a 7.6 MeV alpha demonstrates a time resolution of 425 ps is achieved over an entire S2 detector.

23 226 Ra α source Microchannel plate start det. S2 silicon stop det. Time-of-flight for a 7.6 MeV alpha demonstrates a time resolution of 425 ps is achieved over an entire S2 detector. Time resolution increases by just 70 ps for every 1 MeV decrease in energy E 1 2 mv m s t 2 2 R.T. desouza et al., Nucl. Instr. Meth. A (in press)

24 FAST TIMING TRIGGER Si det. Pie (x48) SLOW (ENERGY& TIME) PICOSYSTEMS Si det. Ring (x160) MASE MASE: Multiplexed Analog Shaper Electronics

25 MASE channelboard (yes, we designed and built it!) POWER LVDS SHAPER, PEAK-FIND/ HOLD, DISCRIMINATOR Slow control of Gains Thresholds triggering masks (Isolated) USB I N P U T S TVC JTAG A Channel board measures 16 in. x 9 in. Logical decisions are made by a Xilinx Spartan and 200 (master-slave) Slow controls of gains, thresholds, triggering masks via isolated USB interface

26 MASE crate configuration test setup : LASSA 500 m detector; 241 Am source MASE exhibits resolution of 30 kev for a 5.4 MeV, comparable to the conventional PICOSYSTEMS + peak sensing ADC.

27 Stage 4: Downstream MCP 40 mm MCP same design as MCP18 prototype of position sensitivity in 2D

28 Stage 5: Zero degree IC (ZDIC) LEFT CENTER RIGHT B E A M conventional transverse field, Frisch gridded IC approximately 15 cm diameter window of 2.5 µm mylar segmented anodes (side anodes quiet relative to center)

29 Good cheese, cider Accelerator facility with excellent technical support ISOL technique Primary beam: Ar Production target: C(graphite) CIME reacceleration: ~10 MHz 20 O 2+ t 1/2 : 13 s 100 feet

30 Installed at GANIL (line G22, May 2010)

33 Before the beam (with an alpha source) 226 Ra source in front of MCP18 and T2 and T3 time resolution <600 ps

34 Energy loss on multi-anodes of CID is a convenient way to tag 20 F and 20 O event by event! 20 O 20 F pileup Peak assignments confirmed by tuning CIME cyclotron to 20 F!

35 Beam cleanly resolved in ZDIC center anodes at 10 khz Side anodes relatively quiet of beam; elastic visible If the MCP40 was position sensitive this would enhance the data from ZDIC (finer angular resolution for residues)

36 Energy TOF spectrum for a single T2 pie Elastic peak clearly visible. Energy tail due to incomplete charge collection Scattered beam line as expected What is the ghost line separated from the scatter line by ~ 4 ns? This is where the residues are expected!

37 What could the problem be? Since the ghost line occurs with a very large probability, the process must be atomic not nuclear Could scattering of the wires give a false early signal?

sharing/incomplete charge collection removes the ghost

38 Reversing the orientation of the MCP from reflector entry to foil entry: eliminates the charge sharing/incomplete charge collection removes the ghost line from the region of the residues. Testing after returning to Bloomington

39 Additionally eliminating the outer rings of the silicon results in a cleaner spectrum Shutdown of GANIL facility in Dec for ~ 18 months due to upgrade to SPIRAL II makes running the experiment at GANIL not feasible.

20 O + 12 C @ 41 MeV Selection of a residue in T2 in coincidence with a

40 20 O MeV Selection of a residue in T2 in coincidence with a LCP in T3 the presence of the emitted LCP eliminates the atomic background.

41 Measured excitation function for charged particle decay of 32 Si* following fusion of 20 O + 12 C Only ~15% of 32 Si* decays via emission of a charged particle. Cross-section exceeds fusion evaporation model (evapor) by approximately a factor of 2 at higher energies Cross-section falls off more slowly with decreasing energy than predicted

42 Bench-mark reaction: 16 O + 12 C Measured in same experiment as 20 O data Data also taken at WMU Measured cross-section in agreement with model predictions 16 O + 12 C 28 Si* 27 Si + n 27 Al + p 26 Al + p + n 26 Mg + 2p 24 Mg + α 23 Na + α + p 20 Ne + 2α

Looking ahead to ReA3 @ Michigan State University Reacceleration of radioactive beams ay MSU with E/A = 0.

43 Looking ahead to Michigan State University Reacceleration of radioactive beams ay MSU with E/A = MeV by a compact superconducting linac anticipated for late 2011/early 2012 In contrast to SPIRAL, it will be easy to change beam energy eliminating the need for degrading 20 O beam is estimated to have an intensity > 1 x 10 4 pps. Beams of 22 O with an intensity of ~1000 pps are estimated.

Proposed Experimental Setup at ReA3 Entry MCP Active target MCP T3 Si det. T2 Si det. T1 Si det. No need to degrade beam setup only uses MCP and Si dets.

44 Proposed Experimental Setup at ReA3 Entry MCP Active target MCP T3 Si det. T2 Si det. T1 Si det. No need to degrade beam setup only uses MCP and Si dets. Second MCP used as active target target ladder only used for Au elastic scattering and SBD Make MCP gridless to eliminate slit scattering (just starting to test prototype design)

45 Summary Beam intensity and purity made the experiment possible at SPIRAL The degrading approach worked as anticipated We now understand (and have the solution) for the ghost line With this general approach, measuring the fusion excitation function should be feasible at ReA3 Outlook Stable beam experiments 16 O + 12 C, 13 C 18 O + 12 C, 13 C 18 O + 18 O Radioactive beam experiments 20 O + 12 C, 13 C 20 O + 18 O 22 O + 12 C, 13 C + heavier beams (e.g. Si, There are exciting opportunities with this research for PhD students! If you are interested, talk to me or contact me at desouza@indiana.edu

Radiometric Dating (tap anywhere)

Radiometric Dating (tap anywhere) Protons Neutrons Electrons Elements on the periodic table are STABLE Elements can have radioactive versions of itself called ISOTOPES!! Page 1 in your ESRT has your list!