Today's Progress 11. June. 2007

p&Lambda/n&Lambda correlation analysis

Here we perform p&Lambda/n&Lambda correlation analysis with E549+E570 full statistics. For all event topologies, the 5-fold coincidence results (stopped K-, Y, N, X(&pi/p/n/&gamma on a remainning arm)) are presented here.

E549/E570 cycle-by-cycle &Lambda N event statistics. For the primary neutron, selection A is defined by detection software threshold (3 MeVee) and 1/&beta selection (1.6-9.0) to define physical ones. For the primary proton, it is defined by successfull energy loss correction with 'reaction vertex' and layer B hit if the proton is measured on TC. Selection B is defined by the elimination of unhealthy PB counter hit(L-3, R-15 for E549, nothing for E570-1, and R-15 for E570-2).
YN pair(dibaryon/tribaryon channel) case ID(Selection) Angler acceptance PA/PB/NT particle TC particle No. of reconstructed &Lambda No. of event after ANo. of event after B (yield of well-defined &Lambda N pair)
&Lambda p (X+/S0) 1(A-b-1-x) 180 +- 30p + p&pi 1329/1294/514 1271/1256/494 1164+1256+467=2887
&Lambda p (X+/S0) 1(A-b-x-1') 90 +- 45p&pi + p 1217/1186/490 937/916/379 884+916+372=2172
&Lambda n (X0/S+) 1(A-b-3-x) 180 +- 30p + n&pi 12200/12289/4678 4555/4550/1875 4353+4550+1841=10744
&Lambda n (X0/S+) 1(A-b-x-3') 90 +- 45p&pi + n 3711/3908/1389 1675/1678/614 1593+1678+600=3871
&Lambda p (X+/S0) 2(B-a-1-x) 90 +- 45&pi + pp 313/337/157 297/323/149 268+323+142=733
&Lambda p (X+/S0) 2(B-a-x-1') 180 +- 45&pip + p 2901/3002/1277 2416/2476/1050 2310+2476+1027=5813
&Lambda n (X0/S+) 2(B-a-3-x) 90 +- 45&pi + np 6406/6626/2434 1383/1357/532 1309+1357+516=3182
&Lambda n (X0/S+) 2(B-a-x-3') 180 +- 45&pip + n 4376/4438/1678 2460/2489/989 2357+2489+950=5796

The definition of variables are as follows:

&Lambda 4-momentum p&Lambda(0:3)/3-momentum p'&Lambda(3):p'&Lambda(i)=pp(i)+p&pi(i), p&Lambda(i)=p'&Lambda(i) (i=1,2,3), p&Lambda(0)=sqrt(M&Lambda2+|p'&Lambda|2),

Nucleon 4-momentum pN(0:3)/3-momentum p'N(3):pN(i)=p'N(i) (i=1,2,3), pN(0)=sqrt(MN2+|p'N2|)

cos(N&Lambda):p'&Lambda*p'N/(|p'&Lambda|*|p'N|)

N&Lambda total 3-momentum Ptot:sqrt((p&Lambda(1)+pN(1))2+(p&Lambda(2)+pN(2))2+(p&Lambda(3)+pN(3))2)

N&Lambda total energy Etot:p&Lambda(0)+pN(0)

N&Lambda invariant mass Minv:sqrt(Etot2-Ptot2)

4He(stopped K-,N&Lambda)X missing mass Mmiss:sqrt((M4He+MK--Etot)2-Ptot2)

The results are exhibitted below for every event topologies:
  • &Lambda case 1 p 180degree
  • &Lambda case 1 p 90degree
  • &Lambda case 1 n 180degree
  • &Lambda case 1 n 90degree
  • &Lambda case 2 p 180degree
  • &Lambda case 2 p 90degree
  • &Lambda case 2 n 180degree
  • &Lambda case 2 n 90degree