1. Recommissioning the Enge Focal Plane detector Robert Leonard
(Georgia Tech) Richard Longland (NC State) Caleb Marshall (NC
State) Daniel Underwood (NC State)
2. Motivation Improve our understanding of the branching ratio
between the 18 F(p,)19 Ne (rp- process) and 18 F(p,)15 O (HCNO
cycle) reactions Remeasure the 23 Na(3 He,d)24 Mg reaction possibly
improving resolution Improve current models of nucleosynthesis in
novae and Na-O anti-correlation in AGB stars. NeNa/MgNa
reactions[1] HCNO/rp-process critical point[2]
3. Background The Enge detector was created to provide improved
energy resolution over the silicon detector that was originally
used Provided a second position measurement so that particles
incident angles could be measured 22 Ne(3 He,d)23 Na reaction on
both detectors[3]
4. Enge Focal Plane Layout Entire detector is filled with
isobutane Particle passes through kapton window and ionizes the
isobutane causing electrons to be caught with high voltage wire
(front and back) In Delta-E the free electrons are picked up by
charge sensitive pre-amp Scintillator stops particle and provides a
signal for the particles energy Mechanical drawing of
detector[3]
5. Position measurement Zoom in of position measurements[3]
Mechanism for position measurments[3] Ionized electrons are
attracted to the HV wires and gain enough energy to knock off more
electrons causing an avalanche of charge Positive charge is induced
on the AI strip board at location of the particle Image charge is
conducted by strip board and the created signal splits Difference
in timing of the signals is used to measure position.
6. Repairs/Mechanical Testing Ground foil in rear position
section was torn/worn Outgoing signal/isobutane vacuum seal
connections damaged O-rings were dirty and torn Reflective aluminum
around scintillator was old and damaged Attempted to setup in
Split-Pole Spectrograph Pumped in air to test vacuum
7. DAQ System and Data Analysis Original plan was to use MIDAS
to collect data and ROOT to analyze it Wrote script to simulate
signals in an attempt to setup MIDAS without having to use the
detector Used ROOT to analyze generated signals to get a basic
understanding of how to manipulate the signals
8. More Data Analysis Realized that no data could be taken from
the Enge by the end of the summer so we used the APEX detector in
LENA to continue working on software Used SpecTcl to analyze data
instead of ROOT Wrote two plug-ins to measure the position and
energy of particles along the APEX using SpecTcl Setup one of the
scintillators and electronics to be able to calibrate software
using a 60 Co source
9. Calibration of Software Used a 60Co source to make 16
measurements along a scintillator on the APEX detector and
calibrate the position measurement software Calibrated energy
measurement software using the known spectral lines of the 60Co
Actual position = .6564*(channel #) 375.4
10. References [1] J. M. Cesaratto, A. E. Champagne, M. Q.
Buckner, T. B. Clegg, S. Daigle, C. Howard, C. Iliadis, R.
Longland, J. R. Newton, and B. M. Oginni, Phys. Rev. C 88, 065806
(2013) [2]W. P. Tan, J. Grres, M. Beard, M. Couder, A. Couture, S.
Falahat, J. L. Fisker, L. Lamm, P. J. LeBlanc, H. Y. Lee, S.
O'Brien, A. Palumbo, E. Stech, E. Strandberg, and M. Wiescher,Phys.
Rev. C 79, 055805 (2009) [3] Stephen Hale, Globular Cluster
Abundance Anomalies, PhD Thesis(1999)
