HADES Collaboration meeting XXII, FW status for the upcoming HADES beam time Alexander Sadovsky sadovsky@inr.ru Institute for Nuclear Research RAS, Moscow Readiness of FW to the physics run Some results from Sep-2010 beam test Simulation of Au+Au@1.25AGeV : - Usability for LVL1 trigger? - Reaction plane reconstruction HADES Collaboration meeting XXII, May 10 - 13, 2011 Seillac, France

HADES Forward Wall, installed: March 2007 Fully operational: summer 2010 Distance to target 7m 140 small 64 middle cells 84 large 2

Ni+Ni@1.25 AGeV, Sep 2010

or readout electronics ? Ni+Ni@1.25 AGeV, Sep 2010 Z <ADC> <ADC>ratio Z2-ratio of peak n/(n-1) (Z(n))2/(Z(n-1))2 Cell 35 1 329 2 1046 3.18 4/1 =4.00 3 1990 1.90 9/4 =2.25 4 2567 1.29 16/9 =1.77 5 3013 1.17 25/16=1.56 6 3494 1.16 36/25=1.44 Cell 168 1 328 2 693 2.11 4/1 =4.00 3 1879 2.71 9/4 =2.25 4 2680 1.42 16/9 =1.77 5 3157 1.18 25/16=1.56 Cell 297 1 260 2 760 2.92 4/1 =4.00 Small cells 1 50 2 160 3.20 4/1=4.00 3 330 2.06 9/4=2.25 4 570 1.64 16/9=1.77 /KaoS/ Ph.D. Thesis of A.Taranenko, 2001. Lin-Y Problems with PMT gain saturation or readout electronics ? ADC Log-Y Z=1 Z=2 Z=3 Z=4 Z=5 Z=6 ADC

Typical time spectrum: Ni+Ni@1.25 AGeV, Sep 2010, cell 35 Typical time spectrum: two-peak structure observed dN/d(ADC) from 1st time peak spectators with Z=2,3,4 ADC dN/d(ADC) from 2nd time peak spectators with Z=1,2,3 Time [ns] ADC Corresponding spectrum of ADC dN/d(ADC) from tails (slow particles) mainly secondaries ADC ADC

Ni+Ni@1.25 AGeV, Sep 2010, cell 35 Trigger related ? Z3 Time [ns] ADC Time [ns] Time walk: different response for particles with different Z time threshold t3t2 t1 ADC Z3 Z2 Z1 t0 Z3 > Z2 > Z1 t3 < t2 < t1 ADC

Ni+Ni@1.25 AGeV, Sep 2010, cell 35 Trigger selection of Mult.(RPC)>1 Two peaks remain... Time [ns] {(Mult TOF + mult RPC )>1 && Mult TOF<1}

Conclusions: Simulations SHIELD Au+Au@1.25GeV 20k events by M.Golubeva FW works, ready for data taking... Simulations SHIELD Au+Au@1.25GeV 20k events by M.Golubeva hGeant simulation with full reconstruction by K.Lapidus hydra-8.21, hgeant-8.21, full HADES geometry In simulation FW was placed on 5 meters from target (in real data 7 meters) No LVL1 emulation

FW fired cells distribution Au+Au@1.25AGeV Selecting spectators by peak at time-of-flight distrib. in FW cells (left ): inside 2sigma (right): outside2sigma Spectators Secondaries y y 100% hits x [cm] x [cm] 16% dN/dx dN/dx Time [ns] Mean =18.1 Sigma=0.87 74% x [cm] Time [ns] x [cm]

FW multiplicity vs. impact parameter All hits: no restriction on time-of-flight in FW cells Spectators: restriction on time-of-flight in FW cells

Number of fired FW cells (S,M,L) vs. b Small size cells Medium size cells Large size cells b secondaries (top) spectators (bottom) Restriction on time-of-flight at FW cells:

dN/db for different cut on num. fired cells Increasing number of small cells fired selects b~9 dN/db b [fm] Increasing number of medium cells fired selects b~8 dN/db b [fm] Increasing number of large cells fired selects b~6 This can be applicable for centrality selection in off-line analysis. dN/db b [fm]

Centrality trigger with TOF and FW ? Centrality selection with multiplicity conditions in FW / TOF dN/db Mult(TOF) is preferable for LVL1 b [fm]

Reconstruction of reaction plane 288 channels scintillator hodoscope located 5 m from the target Reaction plane and centrality determination ⇉ K.Lapidus (CPOD-2010 at JINR) Q > 6 Q > 3 No cut

Forward Wall team NPI Řež: A.Kugler, Yu.Sobolev, P.Tlusty, V.Wagner. INR Moscow: O.Busygina, F.Guber, A.Ivashkin, A.Reshetin, A.Sadovsky, E.Usenko, K.Lapidus (now at Exc.Clust.Univ. & TU-Munich).

Outlook Forward Wall was assembled and fully tested with real data (2010) and ready for Au+Au@1.25AGeV run. Time- and amplitude- parameters of FW were studied. FW response for the Au+Au@1.25AGeV reaction was simulated. Possibilities of the FW use for the reaction plane reconstruction and it's potential usability in LVL1 trigger were demonstrated. Multiplicity in separate regions of FW (small, middle, large cells) can be used in off-line analysis for an additional centrality selection

Backup slides/discussion

Structure of FW with 288 counters

Ni+Ni@1.25 AGeV, Sep 2010 PMT gain saturation Small cell:35 ADC ratio Z2-ratio ratios ratio n/(n-1) (Z(n))2/(Z(n-1))2 “(Z2/Z2)/(ADC/ADC)” 3.18 4/1 =4.00 1.26 1.90 9/4 =2.25 1.18 1.29 16/9 =1.77 1.37 1.17 25/16=1.56 1.33 1.16 36/25=1.44 1.24 2.11 4/1 =4.00 1.89 2.71 9/4 =2.25 0.81 1.42 16/9 =1.77 1.24 1.18 25/16=1.56 1.32 2.92 4/1=4.00 1.36 3.20 4/1=4.00 1.25 2.06 9/4=2.25 1.09 1.64 16/9=1.77 1.08 Small cell:35 peak ADC 1 329 2 1046 3 1990 4 2567 5 3013 6 3494 Middle cell:168 1 328 2 693 3 1879 4 2680 5 3157 Large cell:297 1 260 2 760 KaoS: Ph.D. A.Taranenko (small, ѳ~0.7o) peak ADC 1 50 2 160 3 330 4 570 Lin-Y PMT gain saturation ADC Log-Y ADC

Multiplicities and immact param. distrib. All hits, no restriction on time-of-flight in FW cells

Multiplicities and immact param. distrib. Spectators hits: restriction on time-of-flight in FW cells for spectators

dN/db for number of fired S, M, L cells Small size cells Medium size cells Large size cells b Dependence of number of fired cells (small, medium and large ones) from impact parameter. NB: “hill” of the distribution shifts (no restriction on time-of-flight at FW cells). One may see that large FW cells receive ~20 hits at b=0.

dN/db for number of fired S, M, L cells Small size cells Medium size cells Large size cells b Dependence of number of fired cells (small, medium and large ones) from impact parameter. NB: “hill” of the distribution shifts (restriction on time-of-flight for spectators at FW cells ). One may see that large FW cells receive ~8 hits at b=0.

M(tof), M(rpc) vs M(fw) at different b Impact parameters range influence to M(tof+rpc) vs M(fw) and M(tof) vs M(fw): all particles dN/db b dN/db b dN/db b

M(tof), M(rpc) vs M(fw) at different b Impact parameters range influence to M(tof+rpc) vs M(fw) and M(tof) vs M(fw): spectatrors only (Tfw) dN/db b dN/db b dN/db b

Reaction plane reconstr.: Au+Au@1.25GeV/u no selection 0 < b < 5 no weight Z weight 5 < b < 10 10 < b < 15 43° ⇉ K.Lapidus (HADES coll.meet 2010, GSI)

Reaction plane recons. : Au+Au@1.25GeV/u Cut on Q value helps in suppression of tails and improves the resolution 5 < b < 10 Q > 6 Q > 3 No cut 37o ⇉ K.Lapidus (HADES coll.meet. 2010, GSI)