From CATE to LYCCA Mike Taylor Particle Identification After the Secondary Target

Rising Fast Beam Campaign “Isospin Symmetry and Coulomb Effects Towards the Proton Drip-Line” Proposed experiment: (M. A. Bentley, Oct 2003)  ray spectroscopy of exotic proton rich nuclei Study the T=3/2 mirror nuclei 53 Mn/ 53 Ni, basis for Ph. D. thesis (G. Hammond) 58 Ni 600 MeV/u ~ 5x10 8 pps 9 Be 4 g/cm 2 production target 9 Be 700 mg/cm 2 secondary target 55 Ni ~ 175 MeV/u ~ 4x10 3 pps 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

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

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

Ni Mg Z resolution from energy loss Requirements for Fragment ID A resolution from total energy

Cate energy corrected for beam energy spread Don’t see distinct peaks corresponding to the isotopes with comparable cross- sections Cross-sections from EPAX 2.1 Isotopic Separation From Total Implantation Energy 52 Fe : σ ~ 30 mb 53 Fe : σ ~ 50 mb 47 V : σ ~ 19 mb 48 V : σ ~ 20 mb 49 V : σ ~ 9 mb

Iron Analysis * * * * * Event-by-event tracking and β determination Doppler corrected, time gated and background subtracted NO mass gate * 52 Fe 53 Fe * 52 Fe: E(2 + →0 + ) = 849 keV E(4 + →2 + ) = 1535 keV 53 Fe: E(9/2 – →7/2 – ) = 1328 keV E(11/2 – →9/2 – ) = 1011 keV E(5/2 – →1/2 – ) = 683 keV

a) b) c) d) b c d a 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

Mass Gated Fe Gamma Spectra To improve statistics can apply larger cuts, again different gamma spectra emerge 53 Fe gamma at 861 keV

52 Fe Gamma Spectrum Scaled 53 Fe background spectrum subtracted (2 + →0 + ) (4 + →2 + )

Fe Gamma Gated Mass Spectra Fe: 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 52 Fe 53 Fe

* * * Vanadium Analysis Same conditions as for the Fe analysis Again NO mass gate applied here * 49 V 48 V * 49 V: E(11/2 – →7/2 – ) = 1022 keV 48 V: E(5 + →4 + ) = 428 keV E[(7 + →6 + ),(6 + →4 + )] = 628,627 keV

V Gamma Gated Mass Spectra 48 V: FWHM = 5.5% Isotopic separation not clear Goldhaber spread increases with nucleon removal 48 V 49 V

* * 54 Ni: E(2 + →0 + ) = 1392 keV E(4 + →2 + ) = 1227 keV 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 54 Ni : σ ~ 5 mb 53 Ni : σ ~ mb

Population of Excited Nuclear States investigated by In-Beam Gamma- Ray Spectroscopy of Relativistic Projectile Fragments F. Becker et al., to be submitted to EPJ ABRABLA: population intensity as a function of spin Comparison between calculations and experiment

Simple Job NOT Good Enough ! Difficult to perform γ -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 Need more information along with total energy to obtain good mass identification such as Time-of-Flight

Lund-York-Cologne CAlorimeter (LYCCA) Diamond ? Start TOF DSSD’s Light particle energy detection Diamond ? Stop TOF DSSD’s particle energy loss (ΔE) CsI detectors particle energy (E) detection DSSD’s: 6cm x 6cm, 32 x 32 strips Two modules i)LCP detection ii) Fragment identification CsI’s: 2cm x 2cm, 3 x 3 x 3 array 1.1 cm thick Fragment identification from ΔE, E and TOF beam from Super FRS

Test the sensitive detector response with a simple simulation Simulation of CATE: Geant4 + ROOT 58 Ni (215 MeV/u) beam After SC MeV/u E loss through 300μm SiCode ΔE (MeV) SRIM ATIMA LISE G4 Sim230.5 Si: 9 detectors 5cm x 5cm x 300μm CsI: 9 detectors 5.4cm x 5.4cm x 1cm

Si energy resolution: 1.6% FWHM CsI energy resolution: 1% FWHM Diamond energy resolution: 1% FWHM Diamond time resolution: 50ps FWHM Implementation of Timing Detectors Diamond (CVD) timing detectors 16cm x 16cm x 100μm Diamond detector distance Tgt-Si expt 1.44m Sim also: 2m, 3m Max: 3.5m Signals Collected: Si & CsI x,y position energy segment number Diamond x,y position energy time Need to simulate fragments after the secondary reaction !

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 1.Fragment number 2.X-position (cm) 3.X angle (mrad) 4.Y-position (cm) 5.Y angle (mrad) 6.Energy (AMeV) 7.Time (ps) 8.Mass (amu) 9.Z 10. Charge state

Generation of Simulation Event File

Simulation Results: Fragment XY Distribution Fragment x,y distribution across the nine Si detectors of CATE

175 MeV/u 55 Ni beam primary events 700 mg/cm 2 9 Be target 91 fragments produced with cross-sections > mb (Z range: Ni – S) Tgt-Si distance 2.02m Fragment Identification From Energy Signals Simulation Data Fragments + unreacted beam Simulation Fragments only Ni Co : Ti : S NO gamma gate on sim !

Si Detector Energy Signals Fragment yield varies with scattering angle due to number of protons removed

CsI Detector Energy Signals Fragment yield varies with scattering angle due to number of nucleons removed

Analysis of Time Signals TOF distance = 2m3m 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

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

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

Cobalt Gated TOF vs Energy A σ (mb) 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

Titanium Gated TOF vs Energy A σ (mb) 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

Sulphur Gated TOF vs Energy A σ (mb)

102 Sn + 9 Be, 175 MeV/u same profile as 55 Ni beam 700 mg/cm 2 target Fragments only (56) no unreacted beam simulated A~100 Investigation 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

A σ (mb) 936.8x x x x Cadmium Gated TOF vs Energy All fragments Cd gated A crude mass gate could be applied but this is close to the limit of this technique

(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 BeamTargetReaction 36 CaAuCoulex 55 NiBeSec. Frag. 102 SnAuCoulex 132 SnBeTransfer A ~ 200AuCoulex

Towards a LYCCA Prototype (2x3) Array of 6 x 6 cm DSSD’s (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

LYCCA - 0: The Prototype 2 x 4 Array of telescope modules Test different timing detectors Scintillator, Diamond, Silicon

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 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