**Removing one layer from the tracker:** layer 2 TBPS.


    Barrel TBPS {
      numLayers 2  <---- previously 3
      maxZ 1150
      startZMode moduleedge
      compressed true
      innerRadius 230
      ...}
      
Impact parameter resolution is almost identical to the Technical Proposal. 
Slight improvement in the pt resolution due to the reduction of material budget.
 

  Real
  1 GeV	 		        TDR				
	C	I		C	I	
  pT	0.42274 0.9349          0.43846 1.00621
  d	0.0055	0.00713		0.00533	0.00703	
  z0	0.00722	0.01342	        0.00723	0.01342	
      
  Ideal    
  1 GeV	   	                TDR				
	C	I		C	I	
  pT	0.01058 0.03605         0.00979 0.03174
  d	0.00089	0.00110		0.00088	0.00107	
  z0	0.00269	0.00271	        0.00264	0.00270	     
  
N.B: The pt resolution degrades for higher pt tracks in the layout with one tracker layer less(this is not the case for impact parameter resolution).

Effects of removing the pixel detector. Comparison of pixel only, tracker only, and pixel + tracker.

  1 GeV	TDR pixel					TDR tracker				TDR pixel + tracker				
  	C	I	F	VF	WF		C	I	F	VF	WF	C	I	F	VF	WF
  pT	2.34579	3.62749	3.65583	3.90297	11769598	0.47026	1.31704	2.03956	22.3053	na	0.44211	0.97271	1.45863	2.96898	11769598
  d	0.00625	0.00816	0.0112	0.01446	39535		0.05517	0.09842	0.14347	1.21462	na	0.00551	0.00713	0.01059	0.01397	39535
  phi	0.00224	0.00321	0.00415	0.00482	10850		0.00276	0.00561	0.00822	0.07888	na	0.00181	0.00257	0.00375	0.00461	10850
  z0	0.00723	0.01342	0.03911	0.11134	0.24704		0.10491	0.18096	0.5193	1.32682	na	0.00722	0.01342	0.03911	0.11134	0.24704
  IDEAL																	
  pT	0.55644	0.86291	0.68587	1.01757	523298		0.01886	0.11209	0.58863	21.2698	na	0.00984	0.03236	0.08781	0.53047	523298
  d	0.00255	0.00268	0.00248	0.00406	1557		0.00411	0.00912	0.03819	1.16717	na	0.00088	0.00106	0.00132	0.00277	1557
  phi	0.00062	0.0008	0.00066	0.00102	454		0.00014	0.0005	0.00235	0.07555	na	0.00006	0.00011	0.00018	0.0006	454
  z0	0.00277	0.00288	0.00358	0.01828	0.06125		0.07664	0.07156	0.14593	1.20911	na	0.00267	0.00266	0.00334	0.01815	0.06125