Understanding thermodynamic properties as a function of N/Z

1. Indiana University + DEMON + GANIL+ GSI + Daresbury + LNS-INFN E432a: Decay of Highly Excited Projectile-like Fragments Formed in dissipative peripheral collisions at intermediate energies PLF* decay • Understanding thermodynamic properties as a function of N/Z • Studying N/Z equilibration allows us to probe mass and energy transport in heavy-ion collisions at intermediate energies. Comparison of PLF* decay (~ 0) with mid-rapidity (low ) Both these issues are related to the density dependence of the asymmetry term! Creation of more “surface material” (low density nuclear matter that is significantly excited) • L.G. Sobotka et al., PRL 93, 132702 (2004) • J. Toke et al, PRC 72 031601 (2005) • L.G. Sobotka et al., PRC 73, 014609 (2006) M.B. Tsang et al., PRL 92, 260701 (2004)

2. Proof of approach in studying PLF* decay TLF* PLF* R. Yanez et al., PRC68, 011602 (2003) Decreasing VPLF* Increasing E* 114Cd + 92Mo at E/A = 50 MeV Event selection: 15≤Z≤46 in 2≤lab≤4 Nc≥5 in 4 Ability to reach high excitation energy (E*/A~6 MeV) and select it. Yield Spectra Composition Quantum states Thermodynamics of surface with varying N/Z Study particles emitted from surface

3. Tidal Effect and Proximity decay 11.35 MeV 3.5 MeV 11.44 MeV 3.03 MeV 3.12 MeV =1.51 MeV gr. st. =6.8 eV 8Be α + α 93 keV Zsource Cluster Zsource Zsource Transverse  Higher Erel Longitudinal  Lower Erel Short-lived state  probes nuclear surface 114Cd + 92Mo at E/A = 50 MeV • Select 2  particles forward of the PLF (15≤Z≤46) • construct statistical background with mixed event technique • Mixed event background in agreement with Monte Carlo simulation

4. β Zsource Zsource Zsource A. B. McIntosh et al., in preparation 20% effect • Erel depends on decay angle, consistent with coulomb tides model • 11 MeV state only evident for transverse decay This demonstrates the level of resonance spectroscopy possible in these reactions with FIRST+LASSA Also intend neutron-fragment resonance spectroscopy!

5. ISiS Experimental Setup Al LASSA FIRST and LASSA are highly segmented  600 Si channels FIRST Measure Z,A,E, T. Paduszynski et al., NIM A 547, 464 (2005) • Keys: • Good event selection of peripheral collisions • High resolution measurement (angle/energy/isotope) for charged particles • Measurement of neutron spectra (DEMON) Data from FIRST commissioning expt.!

6. FIRST + LASSA at TAMU Since E432 proposal: • Scattering chamber built (thin-wall) • FIRST concept proved in commissioning expt. • Publication of initial physics results underway • ASIC readout successfully used in HiRA experiments • New electronics (MASE) to facilitate readout of FIRST near completion. • Integration of VME QDC/TDC into DAQ for DEMON readout.

7. Electronics MASE: Multiplexed Analog Shaper Electronics (Readout of FIRST) 512 channels in 2 crate configuration C. J. Metelko et al., in preparation HiRA ASIC (HINP16C) George L. Engle et al., submitted to NIM (Preamps, Shaper, Discriminator, TAC) (Readout of LASSA)

8. Neutron enrichment of low-density nuclear matter MRS (low ) QP (normal ) 64Zn + 64Zn at E/A=45 MeV (commissioning expt. for FIRST) Limited neutron statistics! (only 7 n-TOF detectors) • no initial driving force to N/Z equilibrate • low density mid-rapidity (MRS) is neutron-rich in comparison to high density (QP). • Different behavior is observed for the emitted charged particles (large clusterization of N=Z at low density) • Observation of enrichment above that of the system’s N/Z requiresmeasurement of free neutrons. Systematic measurement of N/Z enrichment with driving force needed  cross-bombardment reactions D. Thériault et al., in preparation

9. Count rate estimate: We anticipate running at 2 x 103 events/sec. 1000 evt/sec x 50 part/evt x 4 words/part x 32 bits/word  6 Mb/sec. This will correspond to a factor of 60 more data than previous expt. (geometrical efficiency: x 10; running time x 6; interaction rate x 1) N/Z drift Mass drift (N/Z)projectile (N/Z)target E/A=50 MeV Calibration: Fragmentation beams (E/A=20-40 MeV); Time required: 3UT

10. Selected publications

11. Extra slides start here

12. Proposed measurement Statistical decay of nuclear matter as a function of N/Z, size, and E*: Isotope yields (e.g. mirror nuclei), spectral shapes (sensitivity to level density), correlation functions (emission timescales), population ratios, etc. Isospin equilibration/reaction dynamics W.P. Tan et al., PRC 69, 061304(R) (2004) Correlation studies of short-lived particle unbound states

13. FIRST :Forward Indiana Ring Silicon Telescopes Large number of channels use of MASE Design : P.H. Sprunger Device dedicated to measure the decay of the PLF* : Limiting temperature Dynamical process PLF* fragmentation  ... T1 : 200 m Si(IP), S2/ 1mm Si(IP), S2/ 2-3cm CsI(Tl) At 28 cm,  = 2.25-7.05 with  = 0.1 T2 : 300 m Si(IP), S1/ 2-3cm CsI(Tl) At 19 cm,  = 7.37-14.5 with  = 0.4 T3 : 300 m Si(IP), S1/ 2-3cm CsI(Tl) At 9 cm,  = 15.2-28.5 with  = 0.7

14. 5811 5903 5946 6194 6139 6072

15. <M> and Tslope depend linearly on VPLF* • E*/A deduced by calorimetry increases monotonically with increasing dissipation reaching a maximum of approximately 6 MeV. • <E*> attained is independent of ZPLF, depends on VPLF* • Select PLF* size by selecting residue Z. • Select excitation by selecting VPLF* • Vary N/Z by changing (N/Z)proj.,tgt.

16. Al FIRST performance • Resolution: • T1: • A up to  30 • Z up to projectile • T2: A up to  18 • T3: A up to  15 • Second Si of T1 = 1 mm • Particle with large Z • Charge split on the rings T. Paduszynski et al., NIMA547, 464 (2005)