E432a: Decay of Highly Excited Projectile-like Fragments Formed in dissipative peripheral collisions at intermediate energies 1.Understanding thermodynamic properties as a function of N/Z 2.Studying N/Z equilibration allows us to probe mass and energy transport in heavy-ion collisions at intermediate energies. Indiana University + DEMON + GANIL+ GSI + Daresbury + LNS-INFN M.B. Tsang et al., PRL 92, (2004) 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) 1.L.G. Sobotka et al., PRL 93, (2004) 2.J. Toke et al, PRC (2005) 3.L.G. Sobotka et al., PRC 73, (2006) PLF* decay Comparison of PLF* decay (~  0 ) with mid-rapidity (low  )

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

114 Cd + 92 Mo at E/A = 50 MeV Tidal Effect and Proximity decay MeV 3.03 MeV gr. st. 8 Beα + α 93 keV MeV 3.12 MeV  3.5 MeV  =1.51 MeV  =6.8 eV 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 Z source Cluster Transverse  Higher E rel Z source Longitudinal  Lower E rel Short-lived state  probes nuclear surface

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

Keys: 1.Good event selection of peripheral collisions 2.High resolution measurement (angle/energy/isotope) for charged particles 3.Measurement of neutron spectra (DEMON) FIRST LASSA FIRST and LASSA are highly segmented  600 Si channels ISiS Measure Z,A,E,  Al T. Paduszynski et al., NIM A 547, 464 (2005) Experimental Setup Data from FIRST commissioning expt.!

FIRST + LASSA at TAMU Since E432 proposal: 1.Scattering chamber built (thin-wall) 2.FIRST concept proved in commissioning expt. 3.Publication of initial physics results underway 4.ASIC readout successfully used in HiRA experiments 5.New electronics (MASE) to facilitate readout of FIRST near completion. 6.Integration of VME QDC/TDC into DAQ for DEMON readout.

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

MRS (low  ) QP (normal  ) Neutron enrichment of low-density nuclear matter 64 Zn + 64 Zn at E/A=45 MeV(commissioning expt. for FIRST) 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 requires measurement of free neutrons. Limited neutron statistics! (only 7 n-TOF detectors) D. Thériault et al., in preparation Systematic measurement of N/Z enrichment with driving force needed  cross-bombardment reactions

136 Xe Sn6 UT  0 YES 136 Xe Sn6 UT YES 124 Xe Sn6 UT YESNO 124 Xe + 64 Ni6 UT  0 YES 136 Xe Sn6 UT Remove all charged particle dets. except FIRST to assess neutron scattering (N/Z) projectile Calibration: Fragmentation beams (E/A=20-40 MeV); Time required: 3UT Count rate estimate: We anticipate running at 2 x 10 3 events/sec 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) target N/Z drift Mass drift E/A=50 MeV

SystemLabPublications 64 Zn + 64 Zn, MeV/ATAMU NIMA 547, 464 (2005) D. Theriault (in preparation) 114,106 Cd + 98,92 50 MeV/AMSU-NSCL A. McIntosh (in preparation) PRC71, (2005) PRC (R) (2004) PRC 68, (R) (2003) PRC 65, (R) (2002) PRC 65, (2002) 112,124 Sn + 112, MeV/AMSU-NSCL PRL (2004). PRC 69, (2004) Xe + 50 MeV/AMSU-NSCL PRC (2004). 60 Ni + 92, MeV/AANL PRC. 67, (2003). 12 C Th at E/A=16,22 MeVANL and MSU-NSCL PRC 66, (2002) Selected publications

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Proposed measurement Define emitting source by selecting PLF size (Z) and excitation (velocity damping). Measure neutrons with DEMON Measurement with different projectile N/Z Measurement of different N/Z and mass asymmetry Measure N/Z of fragments produced in highly aligned breakups 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 Correlation studies of short-lived particle unbound states W.P. Tan et al., PRC 69, (R) (2004)

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

1. and T slope depend linearly on V PLF* 2.E*/A deduced by calorimetry increases monotonically with increasing dissipation reaching a maximum of approximately 6 MeV. 3. attained is independent of Z PLF, depends on V PLF* Select PLF* size by selecting residue Z. Select excitation by selecting V PLF* Vary N/Z by changing (N/Z) proj.,tgt.

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