1. FW status for the upcoming HADES beam time
Alexander Sadovskiy
Marina Golubeva
Institute for Nuclear Research RAS,
Moscow
HADES Collaboration meeting XXII,
May , 2011
Seillac, France

2. Structure of FW with 288 counters

3. Ni AGeV, Sep10

4. Ni+Ni@1.25 @ 1.25 AGeV, Sep 2010 ratio Small cell 35 Middle cell 168
(n+1)/n (Z(n+1))2/(Zn)2
/1=4.00
/4=2.25
/9=1.77
/1=4.00
/4=2.25
/9=1.77
/1=4.00
9/4=2.25
/1=4.00
/4=2.25
/9=1.77
Small cell 35
peak charge (ADC)
Middle cell 168
Large 297
A.Taranenko
(small, ѳ~0.7o )
peak charge (ADC)

5. Simulations SHILD 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

6. 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)

7. 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)

8. 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]

9. 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

10. 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:

11. dN/db for different cut on num. fired cells
Increasing number of small
cells fired selects b~9
dN/db b
Increasing number of medium
cells fired selects b~8
dN/db b
Increasing number of large
cells fired selects b~6
This can be applicable for the off-line analysis.
dN/db b

12. Centrality trigger with TOF and FW ?
Centrality selection with multiplicity conditions in FW / TOF
dN/db b

13. Outlook Forward Wall is assembled and fully tested with real data
(2010) and ready for run
Time- and amplitude- parameters of FW were studied
Simulation of FW response for the
reaction was analyzed to demonstrate possibilities of
the FW use for the reaction plane reconstruction and
it's potential usability in trigger
FW cells multiplicity can be used during off-line analysis
as an addition centrality selection

14. Backup slides/discussion

15. Ni+Ni@1.25 @ 1.25 AGeV, Sep 2010 Small cell 35 Middle cell 168
Peak
(n+1)/n
ratio (Z(n+1))2/(Zn)2
/1=4.00
/4=2.25
/9=1.77
/1=4.00
/4=2.25
/9=1.77
/1=4.00
9/4=2.25
/1=4.00
/4=2.25
/9=1.77
Small cell 35
peak mean-pedestal = charge
= 330
= 1030
= 1980
= 2540
Middle cell 168
= 690
= 2030
= 2650
Large cell 297
= 260
= 760
A.Taranenko (small, ѳ~0.7o )
peak charge

16. Ni + Ni @ 1.25 AGeV, Sep10 ADC: for all particles ADC:
22ns<Time<31ns
for spectators

17. Ni AGeV, Sep10
Time:
all hits
Time:
ADC Z=2

18. 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)

19. Beam 0.9 AGeV, Jun10
Ni AGeV, Sep10

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

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

22. 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.

23. 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.

24. 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

25. 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