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Istituto Nazionale di Fisica Nucleare

Istituto Nazionale di Fisica Nucleare. GDS Topical Meeting 2017. OSCAR: a modular low-threshold hodoscope for low energy nuclear reactions I. Lombardo , D. Dell’Aquila, M. Miranda, M. Vigilante and the NUCL-EX Collaboration Dip . di Fisica, Università di Napoli Federico II

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Istituto Nazionale di Fisica Nucleare

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  1. Istituto Nazionale di Fisica Nucleare GDS Topical Meeting 2017 OSCAR: a modular low-threshold hodoscope for low energy nuclear reactions I. Lombardo, D. Dell’Aquila, M. Miranda, M. Vigilante and the NUCL-EX Collaboration Dip. di Fisica, Università di Napoli Federico II & INFN – Sez. di Napoli Univ. Napoli Federico II and INFN – Napoli ivlombardo@na.infn.it Legnaro, 25/01/2017

  2. Application fields of low-thresholdhodoscopes Hodoscope  wall of detectors with goodenergy and angularresolution MS Coupling with magneticspectrometers: angularcorrelationstudies  spectroscopy of particle-emittingstates. Example: X(6Li,d)Ya+Z Univ. Napoli Federico II and INFN – Napoli Hodo Coupling with «tagging» detectors: complete kinematicreconstruction  branching ratios of decay in unboundexcitedstates Example: 14N(d,a)12C*3a Hodo 3α C3N6H6 α d Important: Hodo with particle identification

  3. Application fields of low-thresholdhodoscopes Hodoscope  wall of detectors with goodenergy and angularresolution Hodo Coupling with active gas target: Improvement in energyrecostruction of high energyejectiles Example: 2H(X,Y)p and similar, athigh energy Hodo Univ. Napoli Federico II and INFN – Napoli Multi-detector array • Coupling with MF detectors: • QTphysics • Isospindiffusion • QT Multi-BU • IMNS • Example: HI+HIX+12C*3a Hodo Hodo Development of new hodoscopes

  4. A new versatile hodoscope: OSCAR OSCAR: hOdoscope of Silicons for Correlations and Analysis of Reactions Strip Si 20 mm (nominal!)  Micron Std. SSSSD  16 strip , 3 mm wide; 0.125 mm interstrip Charge PRE, 16 ch. NET Inst. (45, 90 mV/MeV) Univ. Napoli Federico II and INFN – Napoli Siliconpads, 300 mm (HAM.) Charge PRE 22mV/MeV Twoboards plug and play Front-End  Analogic Digital one Test and Characterization at LNS - INFN

  5. Geometries and MC simulations TEST of OSCAR at LNS: 40,48Ca+40,48Caat35 A MeV OSCAR wasplacedat102 cm from the target, qlab = 52o Univ. Napoli Federico II and INFN – Napoli • 4 strip in onepad geometricaloverlap • Exp. data  fragment AD in LAB • Solid angles  MC simulations • + cross checkwith Rutherford • scattering Nice granularities  30-40 cm

  6. Isotopicresolution and energythresholds TEST of OSCAR at LNS: 40,48Ca+40,48Caat35 A MeV • Isotopicidentification up to Li • Verylowthresholds • (≈ 1.2 A MeV) Univ. Napoli Federico II and INFN – Napoli • Thin dead layer (0.3mm) • Negligibleeffect of electronics on the identificationthreshold • Cross talk levels under control Calculated with the real thickness of SSSSD

  7. Energy resolution TEST of OSCAR at LNS: 40,48Ca+40,48Caat35 A MeVand a - source Univ. Napoli Federico II and INFN – Napoli a source Ca+Ca • Pu-Am-Cm source in DE-E • dE ≈ 70 keV FWHM Very good  nuclear spectroscopy

  8. A criticalpoint: the SSSSD thicknessuniformity Map of the SSSSD thickness new LNSfacility Si + electronics 2 mm collimator SSSSD mobile support a 2 mm collimator a Source 241Am Univ. Napoli Federico II and INFN – Napoli • High non-uniformity (with thispeculiar pattern) siliconwafer cut (20 mm!) • FUNDAMENTALaspect influenceisotopicresolution Worsening of I.R. going towards the RD corner

  9. A criticalpoint: the SSSSD thicknessuniformity Map of the SSSSD thickness new LNSfacility • We can investigate how the thicknessgradient of the large surface SSSSD influence the I. R. • Mass spectra from the DE-E line with an analyticalmethod  Bethe-Bloch formula • N. Le Neindre et al, NIM A 490 (2002) 251 Univ. Napoli Federico II and INFN – Napoli Good mass resolution sA only if t/y < 0.3 mm/mm. Mandatory requirement! Energy loss effect, but … t/y … does the channeling play a role?

  10. Channelingeffects on ultra-thin detectors In the literature  veryfewstudies on channelingeffects in ultra- thin Si detectors  important to preventloss of energyresolution Si 14.5 mm a241Am Our SSSSD, 21 mmthick «pixel» Channeling (higher residualenergy) Non channeled (gaussian) Univ. Napoli Federico II and INFN – Napoli G. Thungstrom et al, NIM A 546 (2005) • From the difference with respect to a purelygaussian trend: •  channeledcomponent • about15% Tilt is needed!

  11. Channelingeffects on ultra-thin detectors Estimate of the channelingeffect in the SSSSD: 1) By subtraction of the gaussian component(quantitative, butdifficultiesBraggregion) 2) By using the skewnessg of residualenergyspectra(qualitative) preliminary Univ. Napoli Federico II and INFN – Napoli Some dependence on the thickness: > thickness > channeling Butatverylowthicknesses??? Quasi – flatbehaviour? G. Thungstrom et al, NIM A 546 (2005) Further investigations

  12. 40,48Ca+40,48Ca at 35 A.MeVresults Lowenergypart of LCP andfragmentspectraisotopicallyresolved (H, He, Li, Be) Univ. Napoli Federico II and INFN – Napoli QT investigation (barriers, N/Z, etc.)

  13. 40,48Ca+40,48Ca at 35 A.MeVresults Lowenergypart of LCP andfragmentspectra  QT emission 48Ca+48Ca 48Ca+40Ca Univ. Napoli Federico II and INFN – Napoli 40Ca+40Ca N/ZQP N/Z1 N/ZMV N/Z2 N/ZQT Signals of isospindiffusion

  14. Unboundfragmentemission: correlations Use of OSCAR for correlations complexfragmentemission Projectile Target Secondary decays Pre-equilibrium, stopping, compression Fragmentation Flow, expansion Univ. Napoli Federico II and INFN – Napoli • LCP correlationspossible • Due to the limitedstatistics 4He+4Hecorrelation (8Be) • Verynicepeakat92 keV (8Begs) • Erelresolution: ≈ 50 keV FWHM 4He+4He correlation Good correlator for LCP

  15. Summary and Conclusions • Hodoscopes goodcandidates to be usedaspowerfulancillary detectors in a large variety of experiments • OSCAR: a new low-threshold and high granularity, modular, hodoscope • 20 mm + 300 mm Si Strip – Si paddetector, 5×5 cm2 area • Test of the detector performances: mass and energyresolution • Problems: gradient of thickness, channeling in ultra-thin detectors • Results on QT emission in Ca+Cacollisionsat 35 A.MeV • 4He+4Hecorrelations with OSCAR  powerfulcorrelatorproperties Univ. Napoli Federico II and INFN – Napoli Thankyou for yourattention!

  16. Further Slides Univ. Napoli Federico II and INFN – Napoli

  17. Alcuni risultati di Fisica – 2 Rapporti isotopici per il QT (selezioni in vpar)  isospindiffusion 48Ca+48Ca 40Ca+40Ca Univ. Napoli Federico II and INFN – Napoli 48Ca+40Ca ISOBARIC RATIO S. Albergo, S. Costa, E. Costanzo, A. Rubbino, Nuovo Cim A 89 (1985) Applicazioni a SPES@LNL

  18. Overview di OSCAR a source spectrum – 300 mm OSCAR: Odoscopio di Silici per le Correlazioni e le Analisi di Reazioni Strip Si da 20 mm (nominali!)  Micron sct. SSSSD  16 strip da 3 mm; 0.125 mm interstrip Pre di carica a 16 vie NET Inst. (45, 90 mV/MeV) Univ. Napoli Federico II and INFN – Napoli Pads di Silici da 300 mm (Ham.) Preamplificatori di Carica 22mV/MeV Due schede  plug and play Elettronica Front-End  analogica (per adesso) Tests e caratterizzazioniai LNS - INFN

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