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Development of OSCAR: A Modular Low-Threshold Hodoscope for Low Energy Nuclear Reactions

This paper presents OSCAR, a modular low-threshold hodoscope designed for low energy nuclear reactions. The system, developed by the NUCL-EX collaboration at the University of Naples Federico II and INFN-Napoli, offers improved energy and angular resolution, enabling advanced spectroscopy and angular correlation studies. Applications include coupling with magnetic spectrometers and tagging detectors for complete kinematic reconstruction. The results from tests demonstrate OSCAR's effectiveness in isotopic identification and energy resolution, significantly enhancing nuclear spectroscopy capabilities.

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Development of OSCAR: A Modular Low-Threshold Hodoscope for Low Energy Nuclear Reactions

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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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