Fazia Applications Silvia Piantelli INFN-Sezione di Firenze Italy

Outlook The FAZIA Project The FAZIA recipe Some physics results with a prototype telescope The first physics experiment (June ) Short and midterm plans

The Four-  A and Z Identification Array Project Design and construction of a 4  detector for A and Z identification with high resolution and low thresholds to be used with standard (GANIL, LNL, LNS) and radioactive (SPIRAL2, SPES, EURISOL) beams at AMeV. Involved institutions: INFN (Firenze, Napoli, LNL, LNS, Bologna, Padova), Italy LPC, IN2P3-CNRS,ENSICAEN, Universite’ de Caen, GANIL, France CEA/DSM-CNRS, IPN Orsay, Universite’ Paris-Sud XI, France Dipartimento di Fisica Università di Firenze, Italy Dipartimento di Fisica Università di Bologna, Italy Dipartimento di Fisica Università Federico II Napoli, Italy Jagellonian University, Institute of Nuclear Physics IFJ-Pan, Krakow, Poland Heavy Ion Lab., Warsaw University, Warsaw, Poland Very long R&D phase started in 2006 concerning detectors, electronics, identification techniques

The FAZIA Project Detector layout:  Blocks of 16 20x20 mm 2 Si (300  m) – Si (500  m) – CsI (10 cm) (read out by a photodiode) telescopes  Fully equipped with digital electronics  Si detectors are reverse mounted to improve Pulse Shape Analysis Identification techniques:   E –E for particles punching-through the first 300  m Si layer full Z identification; A identification up to Z  23  Pulse Shape Analysis (E-Q trise or E-I max ) for particles stopped in the first Si layer: full Z identification (for Z-dependent minimum range in Si (> 30  m)) A identification - up to Z  15 - for A- dependent range (> 150  m)  Time of flight

Status of the FAZIA Project The FAZIA Collaboration started in 2006 (R&D phase) In many tests of some prototypes of the telescope under beam at LNL-INFN (Legnaro, Italy), LNS-INFN (Catania, Italy), GANIL (Caen, France) Very good performances in terms of identification capability (mass and charge) and thresholds December 2014 commissioning of the first block (16 telescopes arranged in 4 four-leaf clovers) June 2015 first physics experiment with 4 blocks Fall 2015 second physics experiment with 4 blocks  2016 FAZIETTO: 12 blocks coupled to INDRA at GANIL  2020 SPES………..

The results of the R&D phase are summarized in many technical papers: 1.L.Bardelli et al., NIMA 491 (2002) 244 (digital sampling applied to scintillators) 2.H.Hamrita et al., NIMA 531 (2004) 607 (Charge and current preamp.) 3.L.Bardelli et al., NIMA 521 (2004) 480 (about time measurements by means of digital sampling technique) 4.L.Bardelli et al., NIMA 560(2006) 524 (about digital sampling technique) 5.G.Pasquali et al., NIMA 570 (2007) 126 (on line analysis of Si signals by means of a DSP) 6.L.Bardelli et al., NIMA 572 (2007) 882 (timing synchronization) 7.S.Barlini et al., NIMA 600 (2009) 644 (PSA from current signal I) 8.L.Bardelli et al., NIMA 602 (2009) 501 (measurement of the resistivity of Si detectors by means of a laser) 9.L.Bardelli et al., NIMA 605 (2009) 353 (effect of channeling on PSA) 10.L.Bardelli et al., NIMA 654 (2011) 272 (PSA technique; E-rise time vs. E-Imax) 11.S. Carboni et al., NIM A 664 (2012) 651 (resolution obtained with PSA and  E-E in FAZIA telescopes) 12.G.Pasquali et al., EPJA 48 (2012) 158 (single chip telescope – CsI read out by Si2) 13.N.LeNeindre et al., NIMA 701 (2013) 145 (about front vs. reverse mounting of Si) 14.S.Barlini et al., NIMA 707 (2013) 89 (about radiation damages) 15.G.Pasquali et al., EPJA 50 (2014) 86 (about underdepleted Si detectors) 16.R.Bougault et al., EPJA 50 (2014) 47 (general summary paper)

The FAZIA recipe in a nutshell n-TD Si detectors with good doping uniformity (<3% FWHM)

Doping uniformity: effects on PSA (particles stopped in the first Si) L.Bardelli et al., NIMA 654 (2011) 272

The FAZIA recipe in a nutshell n-TD Si detectors with good doping uniformity (<3% FWHM) Si thickness uniformity within  1  m (for thicknesses of 300  m and 500  m)

The FAZIA recipe in a nutshell n-TD Si detectors with good doping uniformity (<3% FWHM) Si thickness uniformity within  1  m (for thicknesses of 300  m and 500  m) Si detectors obtained from wafers cut at 7° off the axis, to minimize channeling

Channeling: effects on  E-E L.Bardelli et al., NIMA 654 (2011) 272

Channeling: effects on PSA L.Bardelli et al., NIMA 654 (2011) 272

The FAZIA recipe in a nutshell n-TD Si detectors with good doping uniformity (<3% FWHM) Si thickness uniformity within  1  m (for thicknesses of 300  m and 500  m) Si detectors obtained from wafers cut at 7° off the axis, to minimize channeling Reverse mounting of the Si detectors (essential for PSA)

Front vs. Rear Injection Identification thresholds Shape difference between light and heavy ions maximized for rear injection (entrance from low electric field side) N.LeNeindre et al., NIMA 701(2013)145 Range=289  m Range=182  m Range=286  m Range=203  m Z=22 Z=6 Same detector used in rear and front injection

The FAZIA recipe in a nutshell n-TD Si detectors with good doping uniformity (<3% FWHM) Si thickness uniformity within  1  m (for thicknesses of 300  m and 500  m) Si detectors obtained from wafers cut at 7° off the axis, to minimize channeling Reverse mounting of the Si detectors (essential for PSA) 30nm thick Al layer on both sides of the Si in order to reduce sheet resistance to few  (better timing properties, useful for rise time measurement in PSA)

Effect of sheet resistance Rise time of a signal induced by a laser If sheet resistance is not kept low (few  ), the rise time depends on the impact point on the detector thus worsening PSA S.Valdré, Degree Thesis, University of Florence, 2009 x y Without Al layer

The FAZIA recipe in a nutshell n-TD Si detectors with good doping uniformity (<3% FWHM) Si thickness uniformity within  1  m (for thicknesses of 300  m and 500  m) Si detectors obtained from wafers cut at 7° off the axis, to minimize channeling Reverse mounting of the Si detectors (essential for PSA) 30nm thick Al layer on both sides of the Si in order to reduce sheet resistance to few  (good timing properties, useful for rise time measurement in PSA) Purposely developed Front End Electronics and preamp located inside the vacuum chamber (to reduce noise)

The block and the Front End Electronics Preamp Digitizers FPGA for on line data shaping Si HV Optical fibers 3Gb/s

The FAZIA recipe in a nutshell n-TD Si detectors with good doping uniformity (<3% FWHM) Si thickness uniformity within  1  m (for thicknesses of 300  m and 500  m) Si detectors obtained from wafers cut at 7° off the axis, to minimize channeling Reverse mounting of the Si detectors (essential for PSA) 30nm thick Al layer on both sides of the Si in order to reduce sheet resistance to few  (good timing properties, useful for rise time measurement in PSA) Purposely developed Front End Electronics and preamp located inside the vacuum chamber (to reduce noise) Proper algorithms for digital signal shaping have been developped (e.g. trapezoidal shaping of the digitized signal form)

Development of proper algorithm: PSA from Energy vs. Imax Search for the maximum of the current signal with cubic interpolation on 4 consecutive samples Search for the maximum of the current signal without interpolation among the acquired samples Better mass resolution I max E E

The FAZIA recipe in a nutshell n-TD Si detectors with good doping uniformity (<3% FWHM) Si thickness uniformity within  1  m (for thicknesses of 300  m and 500  m) Si detectors obtained from wafers cut at 7° off the axis, to minimize channeling Reverse mounting of the Si detectors (essential for PSA) 30nm thick Al layer on both sides of the Si in order to reduce sheet resistance to few  (good timing properties, useful for rise time measurement in PSA) Purposely developed Front End Electronics and preamp located inside the vacuum chamber (to reduce noise) Proper algorithms for digital signal shaping have been developped (e.g. trapezoidal shaping of the digitized signal form) Applied voltage across the detector kept constant (on line monitoring of the reverse current)

The quality of the obtained identification is extremely good S.Carboni et al., NIMA 664 (2012) 251 Particles punching through Si 1

S.Carboni et al., NIMA 664 (2012) 251 PI from  E-E Particles punching through Si 1

PSA from Energy vs. Charge rise time S.Carboni et al., NIMA 664 (2012) 251 Particles stopped in Si 1

PSA E-Imax Commissioning (december 2014) Z=10 Particles stopped in Si 1

Fazia shows very good performances in terms of Z and A identification, with low thresholds. Fazia Applications Which physics can be done with FAZIA exploiting at best its capabilities? We can investigated phenomena related to the isospin of the ejectiles

Why measuring the isospin of the ejectiles is important? Because it can give information on isospin transport phenomena Isospin transport phenomena depend on the symmetry energy S(  ) term of the nuclear equation of state; S(  ) is not well known far from normal conditions S(  0 )  30MeV from Weiszacker mass formula EOS for symmetric matter Studying isospin transport phenomena we can get information on the symmetry energy term

Why measuring the isospin of the ejectiles is important? Because it can give information on isospin transport phenomena Isospin transport phenomena depend on the symmetry energy S(  ) term of the nuclear equation of state; S(  ) is not well known far from normal conditions Isospin transport arises because n and p are subject to different forces The isospin gradient  I between target and projectile (in isospin asymmetric reactions) is responsible of the isospin diffusion process, sensitive to S(  ) The density gradient  between the QP/QT region (at normal density) and the more diluted neck zone (both in symmetric and asymmetric reactions), is responsible of the isospin drift, sensitive to  S/  V.Baran et al., Phys. Rep. 410 (2005) 335 M.DiToro et al., J.Phys.G 37 (2010) Difference between the neutron and proton currents

Some experimental results on isospin transport effects with 1 FAZIA telescope: Test experiment done in 2011 at LNS-INFN 84 Kr+ 112,124 Sn at 35AMeV N/Z projectile = 1.33; N/Z 112Sn =1.24; N/Z 124Sn =1.48 Only inclusive measurements Angular coverage: 4°-6° (just beyond the grazing angle) Only products coming from QP phase space are accessible QP residues QP fission products Neck emission QP evaporation

Isospin diffusion Isospin drift /Z of QP phase space products systematically higher when the target is nrich /Z of neck emitted fragments higher than /Z of QP evaporated fragments No dependence on lab velocity for QP fission fragments Neck QP evap S.Barlini et al., PRC87(2013)054607

We have found evidence of isospin drift and diffusion. But… In order to extract information on the EOS it is necessary to compare experimental data with the predictions of transport models, including also the de-excitation stage by means of afterburner codes. As a consequence, it is important to investigate all the aspects which could affect the decay of hot primary products and which might be not completely included in statistical decay codes, such as Z and N staggering

Z and N staggering Ratio among experimental yields and a smoothing curve S.Piantelli et al., PRC88 (2013) N staggering greater than Z staggering for our systems Z staggering greater for n-poor system N staggering more similar for both systems The staggering decreases when the size of the fragments increases Wide range in N

These results have been obtained with a prototype telescope during a test experiment

The most recent experiment (June ): the first physics measurement First use of 4 complete blocks Belt configuration from 3.6° to 17.8°

Ciclope scattering chamber (INFN-LNS) June complete blocks

The most recent experiment (June ): the first physics measurement First use of 4 complete blocks Belt configuration from 3.6° to 17.8° 80 Kr+ 40,48 Ca at 35AMeV N/Z projectile =1.22 N/Z 40Ca =1.0 N/Z 48Ca =1.40 Goals: Extension of the analysis concerning the isospin transport process performed in the test experiment of 2011 (measuring particles and fragments in coincidence) in terms of  Centrality selection by means of the Z biggest - v lab correlation  Identifying light fragments coming from the neck  Identifying QP fission fragments detected in coincidence  Measuring the isotopic composition of both fission fragments  Comparison with transport models (e.g. SMF V.Baran et al., NPA 730 (2004) 329, AMD A.Ono, PRC 59 (1999) 853, BLOB P.Napolitani and M.Colonna )

All the blocks worked: The quality of the identification is equal to the results obtained during the R&D phase with the prototype telescopes Polar representation

Short term plans (  2016): Fazietto 12 blocks +

Towards low energy (  10AMeV) radioactive beams (SPES) Goal: – reduction of the identification thresholds Possible solutions: – ToF measurement (strongly dependent on the flight path) – Use of very thin Si 1 detectors Test under beam done in 2012 telescope with Si 1 =21  m, Si 2 =510  m (standard FAZIA Si 2 ), standard FAZIA electronics

Test with thin Si 1 A.J.Kordyasz et al., EPJA Energy loss calculations Very good Z identification Possible estrapolation of A by means of energy loss calculations PSA in Si 1 not possible (thickness of Si 1 below the threshold of 30  m in range)

FAZIA Collaboration LPC, Caen (F): L.Auger, R.Bougault, N.LeNeindre, O.Lopez, Y.Merrer, M.Parlog, E.Vient GANIL, Caen (F): E.Bonnet, A.Chbihi, J.D.Frankland, Q.Fable IPN, Orsay (F): G.Ademard, B.Borderie, G.Brulin, M.Degerlier, E.Galichet, M.F.Rivet*, F.Salomon, G.Verde INFN – Firenze (I) : G.Casini, D.Gruyer, A.Olmi, S.Piantelli, G.Tobia Dipartimento di Fisica – Univ. di Firenze and INFN – Firenze (I): S.Barlini, M.Bini, P.R.Maurenzig, G.Pasquali, G.Poggi, E.Scarlini, A.Stefanini, S.Valdre’ Dipartimento di Fisica – Univ. di Bologna and INFN – Bologna (I): M.Bruno, L.Morelli INFN – Bologna (I): M.Guerzoni, S.Serra INFN – LNL (I): M.Cinausero, F.Gramegna, T.Marchi INFN – Napoli (I): A.Boiano, R.La Torre, A.Ordine, G.Tortone INFN – Padova (I): D.Fabris Dipartimento di Fisica – Univ. di Napoli and INFN – Napoli (I): L.Francalanza, I.Lombardo, D.Dell’Aquila, E.Rosato*, G.Spadaccini, M.Vigilante INFN – LNS (I): R.Alba, C.Maiolino, D.Santonocito Jagellonian University, Cracow (PL): T.Kozik, M.Palka, Z.Sosin, T.Twarog Warsaw University, Warsaw (PL): A.Kordyasz Huelva University, Huelva (E): J.A.Duenas * deceased