From CATE to LYCCA

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From CATE to LYCCA
Particle Identification After the Secondary Target
Mike Taylor
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Rising Fast Beam Campaign
Proposed experiment (M. A. Bentley, Oct 2003)
Isospin Symmetry and Coulomb Effects Towards the
Proton Drip-Line

• g ray spectroscopy of exotic proton rich nuclei
• Study the T3/2 mirror nuclei 53Mn/53Ni, basis
  for Ph. D. thesis (G. Hammond)

• Analyse, correct and put
• the data into a form in which
• it can be compared to simulations
• Investigate properties that contribute to
  fragment ID
• such as the origin and extent of energy and
  velocity spreads

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Range of nuclei produced

• Many nuclei produced with greater or comparable
  intensity
• to the proposed nucleus of interest 53Ni
• Allows a systematic study of nuclear properties
  across a
• range of nuclei and isotopes
• Possibility of new ?-ray spectroscopy
• 45Cr No ? transitions observed
• 43V Nothing observed, last proton
• only bound by 120 keV

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Particle Identification Detector (CATE)
CAlorimeter TElescope (CATE) consists of an array
of 9 position sensitive Si detectors (DE) and an
array of 9 CsI detectors (E)

• Si detectors
• 5cm x 5cm x 300µm
• Fragment energy loss
• (X,Y) position information
• (after corrections for pin
• cushion effect)

• CsI detectors
• 5.4cm x 5.4cm x 1cm
• Fragment energy (after position dependence
  correction)

Si position correction implemented by G. Hammond
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Requirements for Fragment ID

• Z resolution from energy loss

• A resolution from total energy

Ni
Mg
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Isotopic Separation From Total Implantation Energy

• Cate energy corrected for beam
• energy spread
• Dont see distinct peaks corresponding
• to the isotopes with comparable cross-
• sections
• Cross-sections from
• EPAX 2.1

47V s 19 mb48V s 20 mb 49V s 9 mb
52Fe s 30 mb 53Fe s 50 mb
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Iron Analysis

• Event-by-event tracking and ß determination
• Doppler corrected, time gated and background
  subtracted
• NO mass gate

53Fe E(9/2?7/2) 1328 keV
E(11/2?9/2) 1011 keV E(5/2?1/2)
683 keV
52Fe E(2?0) 849 keV E(4?2) 1535
keV
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Mass Gated Gamma Spectra

• Apply a series of gates on the corrected Total
  Cate energy spectrum
• Project out the associated gammas

• Clear differences in the resulting spectra are
• observed with varying Cate energy cuts
• Low statistics due to small cut regions

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Mass Gated Fe Gamma Spectra

• To improve statistics can apply larger cuts,
  again different gamma spectra emerge
• 53Fe gamma at 861 keV

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52Fe Gamma Spectrum

• Scaled 53Fe background spectrum subtracted

(2?0)
(4?2)
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Fe Gamma Gated Mass Spectra
7506
7610
52Fe 53Fe
53Fe FWHM 2.75

• Lot of work done on this topic by R. Lozeva NIM
  A562, 298 (2006)
• For fragmentation, resolution quoted as being
  between 2-3 FWHM

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Vanadium Analysis

• Same conditions as for the Fe analysis
• Again NO mass gate applied here

49V E(11/2?7/2) 1022 keV

48V E(5?4) 428 keV E(7?6),(6?4)
628,627 keV

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V Gamma Gated Mass Spectra

• Isotopic separation not clear
• Goldhaber spread increases with nucleon removal

48V FWHM 5.5
48V 49V
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Nickel Analysis

• Without clear isotopic separation it is
  extremely difficult to produce
• clean gamma-ray spectra for low cross-section
  isotopes
• Cannot determine to which nucleus new gammas
  belong

54Ni E(2?0) 1392 keV E(4?2) 1227
keV

54Ni s 5 mb 53Ni s 0.009 mb
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Population of Excited Nuclear States investigated
by In-Beam Gamma-Ray Spectroscopy of Relativistic
Projectile FragmentsF. Becker et al., to be
submitted to EPJ

• Comparison between calculations and experiment

• ABRABLA population intensity as a function of
  spin

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• Difficult to perform ?-ray spectroscopy on
  neutron deficient nuclei
• without mass information
• Limited spectroscopic information can be gained
  but only after many
• corrections and analysis tricks
• Goldhaber spread increases with nucleon removal
  so things become
• even more difficult when studying nuclei from
  more than 1 or 2 particle
• removal

Simple Job NOT Good Enough !

• Need more information along with total energy to
  obtain good mass
• identification such as Time-of-Flight

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Lund-York-Cologne CAlorimeter (LYCCA)

• Two modules
• LCP detection ii) Fragment identification

beam from Super FRS
DSSDs 6cm x 6cm, 32 x 32 strips

• Fragment identification
• from ?E, E and TOF

CsIs 2cm x 2cm, 3 x 3 x 3 array 1.1
cm thick
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Simulation of CATE Geant4 ROOT

• Si 9 detectors
• 5cm x 5cm x 300µm
• CsI 9 detectors
• 5.4cm x 5.4cm x 1cm

• 58Ni (215 MeV/u) beam
• After SC41 158.46 MeV/u
• E loss through 300µm Si

• Test the sensitive detector
• response with a simple
• simulation

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Implementation of Timing Detectors

• Signals Collected
• Si CsI
• x,y position
• energy
• segment number
• Diamond
• x,y position
• energy
• time

• Diamond (CVD) timing detectors
• 16cm x 16cm x 100µm

• Diamond detector distance
• Tgt-Si expt 1.44m
• Sim also 2m, 3m
• Max 3.5m

• Si energy resolution 1.6 FWHM
• CsI energy resolution 1 FWHM
• Diamond energy resolution 1 FWHM
• Diamond time resolution 50ps FWHM

Need to simulate fragments after the secondary
reaction !
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MOCADI as an Event Generator

• Monte Carlo code to model ion transport and
  energy loss (uses ATIMA 1.0)
• (Nuc. Inst. Meth. in Phys. Res. B 126, 284)
• Used to optimise experimental setup of FRS at
  GSI
• Models fragmentation reactions using Goldhaber
  momentum distribution
• (Phys. Lett. 53B, 306) (uses EPAX2 for
  cross-sections)
• Option to output events to an ASCII file (no
  cross-sections applied !)

• Variables outputted
• Fragment number
• X-position (cm)
• X angle (mrad)
• Y-position (cm)
• Y angle (mrad)
• Energy (AMeV)
• Time (ps)
• Mass (amu)
• Z
• Charge state

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Generation of Simulation Event File
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Simulation Results Fragment XY Distribution
Fragment x,y distribution across the nine Si
detectors of CATE
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Fragment Identification From Energy Signals
Simulation
Data
Fragments unreacted beam

• 175 MeV/u 55Ni beam
• 130000 primary events
• 700 mg/cm2 9Be target
• 91 fragments produced
• with cross-sections gt 10-2 mb
• (Z range Ni S)
• Tgt-Si distance 2.02m

Simulation
Ni Co Ti S
Fragments only
NO gamma gate on sim !
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Si Detector Energy Signals
Fragment yield varies with scattering angle due
to number of protons removed
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CsI Detector Energy Signals
Fragment yield varies with scattering angle due
to number of nucleons removed
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Analysis of Time Signals

• Separation better at 3m due to
• timing resolution being better as a
• percentage of the total TOF
• Separation worse at high energy
• due to the resolution being a
• percentage of the deposited
• energy

TOF distance 2m 3m
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Calculation of Mass from TOF and Energy
Using the TOF and energy of each detected
fragment the mass can be calculated directly
using a formula. The improvement of resolution
with TOF distance is clear
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ROOT Analysis File Structure

• Raw signal and
• diagnostic spectra
• created and filled
• directly
• Raw and selected
• correlated signals
• written to a ROOT
• TTree object for
• further analysis

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Cobalt Gated TOF vs Energy

• At 2m TOF distance mass
• separation just visible
• At 3m, separation between
• the two isotopes with the
• largest cross-sections is
• much cleaner
• All cross-sections from EPAX2

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Titanium Gated TOF vs Energy

• At 2m the mass separation
• is better than the Co case
• but still a little dirty
• At 3m the separation is
• approaching an ideal case

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Sulphur Gated TOF vs Energy
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A100 Investigation

• 102Sn 9Be, 175 MeV/u
• same profile as 55Ni beam
• 700 mg/cm2 target
• Fragments only (56)
• no unreacted beam simulated

Sn In Cd Ag Pd Rh

• TOF distance set to max 3.5m
• Energy time resolutions
• unchanged
• No clear mass separation from
• total TOF vs Energy plot

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Cadmium Gated TOF vs Energy

• A crude mass gate
• could be applied but
• this is close to the
• limit of this technique

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(Lots) To Do (simulation wise)

• Fix TOF distance to investigate detector
  resolution effects
• Test other timing options Diamond Si, Diamond
  Scintilator
• Change to prototype geometry
• Simulate with Super FRS beam profile
• Simulate test experiments with final setup
• e.g.
• Integrate simulation into full HISPEC simulation

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Towards a LYCCA Prototype
(2x3)x(3x3) Array of 2 x 2 cm CsI Detectors
located 1cm behind the Si array Scintillators
are 1.1 cm thick 0.7 cm behind which are located
1 x 1 cm photodiodes
(2x3) Array of 6 x 6 cm DSSDs
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LYCCA - 0 The Prototype

• 2 x 4 Array of telescope modules
• Test different timing detectors
• Scintillator, Diamond, Silicon

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Project Timeline

• Jan 2007
• 1 test module assembled
• Spring 2007
• Test module to undergo in-beam tests
• 2008
• 2 x 4 array, LYCCA-0 ready for use in next
  Rising
• Fast Beam Campaign. Used to test timing options

Collaborators
M. A. Bentley, University of York D. Rudolph, R.
Hoischen, P. Golubev, Lund University P. Reiter,
University of Köln J. Gerl, M. Górska, GSI
Laboratory Rising Collaboration, GSI NUSTAR
Simulation group