High momentum protons from 12 C fragmentation at intermediate energy B.M.Abramov, P.N.Alekseev,Yu.A.Borodin,S.A.Bulychjov, I.A.Dukhovskoy, A.B.Kaidalov, A.I.Khanov, A.P.Krutenkova, V.V.Kulikov, M.A.Martemianov, M.A.Matsyuk, E.N.Turdakina, Institute for Theoretical and Experimental Physics (ITEP), Moscow, Russia Motivation for nuclear fragmentation study ITEP Heavy Ion Facility - TeraWatt Accumulator Experiment FRAGM: 12 C + A  F + X, T 0 = GeV/n Momentum and kinetic energy spectra of fragments x–distributions for 12 C + Be  p + X and QGS model Comparison with other experimental data Conclusion Presented by A.P. Krutenkova NPD RAS Conference, Moscow, ITEP, Oct-15 1 A.P. Krutenkova, NPD RAS Session

Motivation for nuclear fragmentation study 1.Measurement of nuclear composition of secondary beams at ITEP heavy ion accelerator. 2. Precise measurement of high energy fragment spectra for a) search for cumulative effect in fragment production in heavy ion collisions, b) test of theoretical models in the unstudied region of high momentum. 3. Now systematic data are needed as input to transport codes for radiotherapy with heavy ions, for shielding calculation for long-duration space missions and for RIB design 23-Oct-15 2 A.P. Krutenkova, NPD RAS Session

ITEP Heavy Ion Facility: TeraWatt Accumulator Experiment FRAGM Areas of slow extracted beams from U10 Ring Target hall Building for biological research and proton therapy Areas of secondary beams from U10 Ring Stand for radiation treatment of materials with high intensity beams Material irradiation zone 25 MeV proton LINAC (I-2 ) Area of fast extracted beam Area of fast extracted beam from UK and U10 Rings Area of fast extracted beam from UK Ring 10 m 23-Oct-15 3 A.P. Krutenkova, NPD RAS Session Laser ion source U-10 Ring 10 GeV PS. 8×10 11 ppp 4GeV IS. 4× C/cycle UK Ring 400 MeV IS 2×10 9 ions/cycle

16m 10m Monitor С-12 А В С Scintillation counters А 3(TOF+dE/dx) + H(20x10) B 2(TOF+dE/dx) Trigger = 1A ×1B C 14(TOF) 0.6 ×2.0 m×m - thin foil internal target - bending magnet - quadrupole Experiment FRAGM θ 23-Oct-15 4 A.P. Krutenkova, NPD RAS Session 12 C + Be  p (d, t, 3 He, 4 He, 6 He, 8 He,… ) + X, θ = 3.5 O T 0 = 0.2, 0.3, 0.6, 0.95, 2.0 and 3.2 GeV/n

Relative yields of H and He isotopes at 3.5 o from 12 C fragmentation on Be target at 300 MeV Relative yield Rigidity =p lab /Z, GeV/c (Z is fragment charge) 23-Oct-15 5 A.P. Krutenkova, NPD RAS Session Proton spectrum has non-Gaussian high momentum tail t

Evaporation region tests In the rest frame of the nucleus, momentum distribution of a fragment has Gaussian shape. Parabolic law for r.m.s. of momentum distributions: σ 2 F = σ 2 0 A F (A – A F )/(A-1), (A, A F are masses of nucleus, fragment; σ is standard deviation) A.S. Goldhaber (1974) Limiting fragmentation hypothesis: fragmentation properties are independent of projectile energy and target mass. Proton momentum spectrum in 12 C rest frame (T 0 =300 MeV; fit with Gaussian from -0.2 to 0.1 GeV/c) Invariant cross section (a.u.) vs proton longitudinal momentum (GeV/c) Evaporation region σ =0.073±0.002 GeV/c Preequilibrium region (“cumulative”) 23-Oct-15 6 A.P. Krutenkova, NPD RAS Session Range of cross-section values covers eight orders of magnitude P II, GeV/c Kinematical limit for C+p  p+X Gaussian

T s = 4.3±0.5 MeV Forw.  Backward 23-Oct-15 7 A.P. Krutenkova, NPD RAS Session Triton spectrum is well described by Gaussian Deuteron and triton momentum spectra (T 0 =300 MeV; fit with Gaussian ) χ 2 /ndf = 45.1/31 σ =.162±.003 GeV/c Deuteron spectrum has sizeable high momentum non-Gaussian tail σ =.121±.005 GeV/c

23-Oct-15 8 ALADIN GSI data Au+Au -> p+X at 1 GeV/n Hongfei Xi et al.(1997) Statistical Multifragmentation Model Other Measurements A.P. Krutenkova, NPD RAS Session

Slope parameters from kinetic energy spectra (Ed 3 σ/d 3 p ~ A s exp(-T/T s ) + A c exp(-T/T c ); T 0 =300 MeV) T s = 4.3±0.5 MeV T c = 18.9±0.6 MeV Forw.  Backward 23-Oct-15 9 A.P. Krutenkova, NPD RAS Session Invariant cross section (a.u.) vs rest frame kinetic energy T × sign (p II ) (GeV) Kinetic energy spectrum can be described by two exponents Protons

T c and T s energy dependences for 12 C (scaling value for pA is ~50 MeV) 23-Oct A.P. Krutenkova, NPD RAS Session Slope of preequilibrium (“cumulative”) part increases with T 0 from 16 to 44 MeV Theoretical approaches connect “cumulative” effect with contribution of multiquark states in nuclei TsTs TcTc  T T C &T S, this experiment, C+Be  p+X T C, M.Anikina et al, C+C  p+X, JINR (1986 ) T C &T S,T.Odeh et al, Au+Au  p+X, GSI (2000)

The production of cumulative particles in pA interaction was successfully considered in the framework of the QGSM. Assuming the existence of some coherent clusters in the nucleus and the asymptotic Regge behavior for their structure functions the distribution of quarks in the nucleus was derived and inclusive spectra of cumulative hadrons were analyzed. Production of cumulative particles and Quark-Gluon String Model (QGSM) A.V. Efremov, A.B. Kaidalov, G.I. Lykasov, N.V. Slavin, Phys. Atom. Nucl. 57 (1994) 932 Abstract 23-Oct A.P. Krutenkova, NPD RAS Session

Cumulative protons in QGSM Production of cumulative protons in fragmentation is considered as fragmentation into protons of clusters consisting of 3k valence quarks (k=1: (3q) - nucleon, k=2: (6q) – two-nucleon cluster, k=3: (9q) – three-nucleon cluster); w k is the probability to find k-nucleon cluster in 12 C Fitted variables are: C’, W 2 = w 2 /w 1, W 3 = w 3 /w 1, ,  x 23-Oct A.P. Krutenkova, NPD RAS Session Ed 3 σ/d 3 p(x,p t 2 ) =C’(w 1 g(x,p t 2 )+w 2 b 2 (x,p t 2 )+w 3 b 3 (x,p t 2 )) g(x,p t 2 )=G exp(-0.5 (1-x-  ) 2 /  x 2 ) exp(-0.5 p t 2 /  p 2 ) b 2 (x,p t 2 )=B 2 (x/2) 3 (1-x/2) 3 exp(-   p t 2 ), b 2 (x,p t 2 )=0 at x>2 b 3 (x,p t 2 )=B 3 (x/3) 3 (1-x/3) 6 exp(-   p t 2 ), b 3 (x,p t 2 )=0 at x>3 where g, b 2, b 3 are known fragmentation functions. G, B 2 and B 3 are known normalization constants. Transverse parameters   and     are from PRC 28 (1983) 1224 

QGSM model fit of x=p lab /p 0 spectrum 23-Oct Invariant cross section, arbitrary unit 3q 6q 9q A.P. Krutenkova, NPD RAS Session

x=p lab /p 0 spectra at different energies 3q 3(3q) 23-Oct q 9q 3q A.P. Krutenkova, NPD RAS Session

Probabilities of quark clusters existence T 0, GeV/nw 1 (3q) w 2 (6q) w 3 (9q) (3) 0.13(2).0010(4).004(4) (1).005(2) (2).003(5) C(e,e’) at J-LAB (7) 0.19(4) -.006(2) Quantitative results on few nucleon clusters in nuclei could be obtained from fragmentation data. Wider range on x and wider projectile energy range are desirable 23-Oct A.P. Krutenkova, NPD RAS Session K.S. Egiyan et al (2006) We used fitting procedure to get w 2 and w 3

Conclusion Light fragment momentum and kinetic energy spectra from reaction 9 Be ( 12 C, F)X were measured at T 0 = GeV/nucleon in evaporation and preequilibrium (“cumulative”) regions Momentum spectra in evaporation region are well described by Gaussians in accordance with SM. Proton kinetic energy spectrum in “cumulative” region has exponential shape with slope parameter T c which increases with projectile energy from 16 to 44 MeV. It shows that scaling behaviour is not reached at studied energy range. Probabilities of existence of quark clusters in C-12 were e stimated in QGSM. w 2 ~10% and w 3 <1% are in coincidence with those of two- and three-nucleon SRC measured at J-LAB 23-Oct A.P. Krutenkova, NPD RAS Session

23-Oct Backup slides

Parameters of x spectra T 0, GeV/n P 0, GeV/c/n P t 2, (GeV/c) 2 X max xx W2W2 W3W3 ww w 3 x (6) (6).156(6).152(3).15(4).15(3).0015(4).004(4) 0.13(3) 10(4) 4(4) (3).140(4).11(1).006(2)0.10(1)5(2) (1) -.186(10) -.10(2) (6) 0.09(2) 3(4) (7).180(2).31(9)-0.25(7) (2) Oct A.P. Krutenkova, NPD RAS Session Run 11_04_03

Conclusion Light fragment momentum and kinetic energy spectra from reaction 9 Be ( 12 C, F)X were measured at T 0 = GeV/nucleon. Proton momentum spectra cover evaporation and preequilibrium (“cumulative”) regions; eight orders of magnitude in cross section Momentum spectra in evaporation region are well described by Gaussians “Cumulative” region has exponential shape with slope parameter T c increasing with initial energy from 16 to 44 MeV Estimated probabilities of existence of quark clusters w 2 ~10% and w 3 <1% are in agreement with those of two- and three-nucleon correlations in 12 C nuclei measured at J-LAB 23-Oct A.P. Krutenkova, NPD RAS Session

Mode of operationAcceleratorsBeam energy, MeV/n Regime of beam extraction Proton accelerationI-2 I-2/U-10 I-2/UK 25 up to 230 up to 3000 up to 9300 up to 3000 (9300) up to 3000 pulse, 10  /s, 200 mA medical extraction, 200 ns, c -1 fast extraction, 800 ns, 5x10 11 c -1 internal target, 1s slow extraction, 1s fast and slow extraction, 0,5s Ion acceleration, С, Al, Fe, Ag (Mg,Si,Ti,V,Cr,Cu,Zn) (Pb,Bi,U) I-3/UK I-3/UK/U-10 1,5 – fast extraction, 800 ns, С(2x10 9 ), Al(5x10 8 ), Fe(2.5x10 8 ), Ag(2x10 7 ) slow extraction, 0,5s internal target, 1s, slow extraction, 1s Nuclei accumulation, С, Al, Fe, I-3/UK/U fast extraction with compression to 150 ns, continue extraction of stacking beam ITEP-TWAC Operation Parameters 23-Oct A.P. Krutenkova, NPD RAS Session

Relative yield of H and He isotopes at from 12 C fragmentation on Be target at 600 MeV Beam channel: rigidity P/Z=1.8 GeV/c/Z 23-Oct A.P. Krutenkova, NPD RAS Session

Relative yield of H and He isotopes at from 12 C fragmentation on Be target Rigidity =P lab /Z, GeV/c Relative yield 23-Oct A.P. Krutenkova, NPD RAS Session

Relative yield of H/He isotopes at from 12 C fragmentation on Be target at 600 MeV 23-Oct A.P. Krutenkova, NPD RAS Session

He-3 and He-4 momentum distributions He-3He-4 Ed 3 σ /d 3 p, relative units σ =.148±.003 GeV/c σ =.149±.003 GeV/c 23-Oct A.P. Krutenkova, NPD RAS Session

Ed 3 σ /d 3 p, relative units He-6 He-8 σ =.187±.007 GeV/c σ =.174±.009 GeV/c He-6 and He-8 momentum distributions 23-Oct A.P. Krutenkova, NPD RAS Session

Au+Au at 1000MeV/n for protons. T.Odeh et al. PRL84,4557(2000) Our data for C+Be at 300MeV/n - Comparison with ALLADIN data 23-Oct A.P. Krutenkova, NPD RAS Session

x=p lab /p 0 spectrum at 300 MeV 3q 6q 9q 23-Oct A.P. Krutenkova, NPD RAS Session

x=p lab /p 0 spectra at different energies 3q 3(3q) 23-Oct A.P. Krutenkova, NPD RAS Session 6q 9q 3q

0.3 GeV/n 1.0 GeV/n this exp. Greiner et al. σ 0 p 75.1±3.1 63±4 75.1±3.1 d 121.8± ± ±3.3 t 162.0± ± ±1.5 He ± ± ±1.7 He ± ±3 86.8±1.9 He ± ± ±4.2 He ± ±5.3 σ F comparison with data and theoretical prediction Data: D.E.Greiner et al. PRL35,152(1975) Theoretical prediction: A.S.Goldhaber, PL53B,306(1974) (σ F ) 2 = (σ 0 ) 2 F(A proj. – F)/(A proj, -1), where σ 0 = 90 MeV/c 23-Oct A.P. Krutenkova, NPD RAS Session

Test of Goldhaber parabolic law This experiment – 0.3 GeV/nGreiner et al.- 1GeV/n σ 0 = 94±1 MeV/c χ 2 /ndf =96/6 σ 0 = 74±2 MeV/c χ 2 /ndf =20/5 σ 0 = 90 MeV/c used by SM 23-Oct A.P. Krutenkova, NPD RAS Session

Interpretation of “cumulative” events At high energies “cumulative” (x=p lab /p 0 >1) production in pA was considered by Efremov, Kaidalov et al (1994) suggesting existence of multiquark clusters in nucleus and high energy behaviour of their structure functions in Quark-Gluon String Model (QGSM) Kaidalov proposed to use FRAGM data to estimate the values of probabilities w k to find k-nucleon clusters in 12 C (k=1,2,3) Invariant cross-section was expressed as a sum of three terms: Ed 3 σ/d 3 p(x,p t 2 )=C’(w 1 g(x,p t 2 )+w 2 b 2 (x,p t 2 )+w 3 b 3 (x,p t 2 )) where g, b 2, b 3 are known fragmentation functions (fragmentation through nucleon component (3q), two- (6q) and three- (9q) nucleon clusters, respectively; details at backup slide). w 1 +w 2 +w 3 =1 23-Oct A.P. Krutenkova, NPD RAS Session