AN EMJ CREW INBOUND TO ORD DSNDING AND FOLLOWING A B737; 7 MI AHEAD; ENCOUNTERED WAKE TURB CAUSING THE ACFT TO ROLL SEVERAL TIMES L AND R.

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WE WERE INBOUND ON THE OXI ARR TO ORD. WE CROSSED BEARZ INTXN AT 11000 FT; CALLED APCH AS INSTRUCTED BY ATC. APCH GAVE US A DSCNT TO 7000 FT. I ACKNOWLEDGED THE CLRNC AND THE FO; WHO WAS THE PF; STARTED HIS DSCNT. I MADE A PA TELLING THE FLT ATTENDANT TO PREPARE FOR LNDG. AROUND 10000 FT ON THE WAY DOWN; WE WERE ROLLED SEVERAL TIMES L AND R BY WAKE TURB. I INFORMED ATC OF THE WAKE ENCOUNTER AND ASKED FOR A SLIGHT HDG CHANGE UPWIND. AT THAT TIME WE HAD A LIGHT QUARTERING TAILWIND FROM THE L. ATC'S RESPONSE WAS THAT WE WERE NOT FOLLOWING A HVY; AND INSTRUCTED US TO TURN TO A HDG OF 360 DEGS. AS SOON AS WE TURNED; WE WERE OUT OF THE WAKE TURB. THE ONLY ACT I NOTICED IN FRONT OF US AT THE TIME WAS ABOUT 7 TO 8 MI AHEAD ON THE SAME HDG AND ABOUT 2500 FT BELOW US. UPON ARR AFTER THE PAX DEPLANED; THE FLT ATTENDANT INFORMED ME THAT AS SHE WAS CONDUCTING HER SAFETY COMPLIANCE CHK; SHE HIT HER HEAD IN THE CABIN WHEN WE ENCOUNTERED THE WAKE TURB. SHE TOLD ME SHE FELT OK. AS A PRECAUTION; I HAD HER GO TO HER MANAGER AND FILL OUT A RPT. AS FAR AS THE WAKE ENCOUNTER; I HAVE A THEORY WHY WE ENCOUNTERED WAKE TURB. BUT IT WOULD BE HARD TO PROVE. ONE THING I HAVE NOTICED LATELY; ESPECIALLY ON THE ARRS OVER BEARZ INTXN; IS THAT ATC IS SPACING ACFT CLOSER. IN FACT; EARLIER IN THE DAY ON THE SAME ARR; THEY HAD US FOLLOWING A B747 WHO WAS 5 TO 6 MI AHEAD AND 1000 FT ABOVE AND HAD HIM DSND TO OUR ALT. TO ME IT SEEMS ATC IS SPACING ACFT CLOSER AND COMPROMISING SAFETY TO GET MORE FLTS IN ON A GIVEN TIME. I FEEL THAT THERE WILL BE MORE WAKE ENCOUNTERS UNLESS WE DO WHAT'S NECESSARY TO STAY OUT OF IT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THEY WERE FOLLOWING A B737 AND HAD A LIGHT QUARTERING TAIL WIND OF ABOUT 5 TO 6 KTS. HE SAID THE ACFT ROLLED ABOUT 30 DEGS SEVERAL TIMES. HE THINKS THE SPACING OF ACFT IS TOO CLOSE.