ENTRY A0379 20021217 0000A037900000001
SUBENT A0379001 20021217 0000A037900100001
BIB 13 57 A037900100002
TITLE First measurement of the 3-He(3-HE,2P)4-He cross A037900100003
section down to the lower edge of the solar Gamow peak A037900100004
REFERENCE (J,PRL,82,5205,1999) A037900100005
REL-REF (N,,U.GREIFE+,J,NIM/A,350,327,1994) A037900100006
Techical details of LUNA system A037900100007
AUTHOR (R.Bonetti, C.Broggini, L.Campajola, P.Corvisiero, A037900100008
A.D'Alessandro, M.Dessalvi, A.D'Onofrio, A.Fubini, A037900100009
G.Gervino, L.Gialanella, U.Greife, A.Guglielmetti, A037900100010
C.Gustavino, G.Imbriani, M.Junker, P.Prati, V.Roca, A037900100011
C.Rolfs, M.Romano, F.Schuemann, F.Strieder, F.Terrasi, A037900100012
H.P.Trautvetter, S.Zavatarelli) A037900100013
INSTITUTE (2ITYMIL) Dipartimento di fisica and INFN A037900100014
(2ITYITY) INFN, padova A037900100015
(2ITYLGS) A037900100016
(2ITYNAP) Dipartimento di science fisiche and INFN A037900100017
(2ITYFSN) Dipartimento di science ambientali A037900100018
(2ITYGVA) Dipartimento di fisica and INFN A037900100019
(2ITYFRA) Frascati and INFN, ENEA A037900100020
(2ITYTUR) Dipartimento di fisica sperimentale and INFN A037900100021
(2GERBOC) Institut fuer experimentalphysik III A037900100022
COMMENT Abstract: we give the LUNA results on the cross A037900100023
section measurement of a key reaction of the proton- A037900100024
proton chain strongly affecting the calculated neutrinoA037900100025
luminosity from the sun: 3-He(3-HE,2P)4-He . Because A037900100026
of the cosmic ray suppression provided by the Gran A037900100027
Sasso underground laboratory, it has been possible to A037900100028
measure cross section throughout the energy range in A037900100029
which this reaction occurs in the sun, I.E., Down to A037900100030
16.5 KeV center of mass energy. The data clearly show A037900100031
the cross section increase due to the electron A037900100032
screening effect but they do not exhibit any evidence A037900100033
for a narrow resonance suggested to explain the 8-B andA037900100034
7-Be solar neutrino flux reduction. A037900100035
SAMPLE 3-He gas target A037900100036
DETECTOR (SIBAR) Eight thick (1 millimeter) detectors of 5*5 A037900100037
cm**2 area placed around the beam A037900100038
FACILITY (ACCEL,2ITYLGS) A037900100039
METHOD (SITA) A037900100040
(EXTB) A037900100041
(BCINT) Beam current was measured by calorimeter. A037900100042
(COINC) Selected events must fulfill the following A037900100043
conditions: A037900100044
1. There is a coincidence, within 1 microsecond, A037900100045
between the signal of two silicon detectors. A037900100046
2. Each proton deposits more than 2 MeV in the detectorA037900100047
and the sum of the two proton energies is within the A037900100048
constraints given by the Q-Value, 12.86 MeV, of the A037900100049
reaction. A037900100050
3. The coincidence occurs between two, and only two, A037900100051
detectors. A037900100052
Detection efficiency was determined by Monte Carlo A037900100053
programm as 5.3% +/- 0.2% A037900100054
HISTORY (20020709C) A037900100055
(20021217U) Last checking has been done. A037900100056
ERR-ANALYS (ERR-2) Maximal value of gas pressure uncertainty A037900100057
ADD-RES Electron screening potential energy was detemined as A037900100058
247+/-47 eV A037900100059
ENDBIB 57 0 A037900100060
COMMON 1 3 A037900100061
ERR-2 A037900100062
PER-CENT A037900100063
1. A037900100064
ENDCOMMON 3 0 A037900100065
ENDSUBENT 64 0 A037900199999
SUBENT A0379002 20021217 0000A037900200001
BIB 4 15 A037900200002
REACTION (2-HE-3(HE3,2P)2-HE-4,,SIG,,SFC) A037900200003
MISC-COL (MISC1) Centre of mass energy derived from the absoluteA037900200004
energy of the ion beam and the Monte Carlo simulation, A037900200005
including the energy loss of the beam inside the targetA037900200006
gas and the effects of the extended gas-target and A037900200007
detector geometry. A037900200008
(MISC2) Total charge (in coulombs) of 3-He ions ran A037900200009
across gas target A037900200010
(MISC3) Number of detected reactions. A037900200011
ERR-ANALYS (ERR-S) Statistical error, one standard deviation A037900200012
(ERR-1) Systematical error, one standard deviation A037900200013
the systematical error arising mainly from the 10% A037900200014
uncertaintly in the beam energy loss inside the target.A037900200015
COMMENT - By compiler. Effective beam particle energy was A037900200016
calculated by compiler. A037900200017
ENDBIB 15 0 A037900200018
NOCOMMON 0 0 A037900200019
DATA 8 11 A037900200020
EN DATA DATA-MAX ERR-S ERR-1 MISC1 A037900200021
MISC2 MISC3 A037900200022
KEV B*MEV B*MEV B*MEV B*MEV KEV A037900200023
SEE TEXT NO-DIM A037900200024
33. 7.7 7.7 0.49 16.5A037900200025
349. 1. A037900200026
33.98 13.15 4.98 0.83 16.99A037900200027
827. 7. A037900200028
34.92 5.26 5.26 0.33 17.46A037900200029
189. 1. A037900200030
35.94 14. 17.97A037900200031
272. 0. A037900200032
36.92 7.86 2.97 0.47 18.46A037900200033
337. 7. A037900200034
37.96 8.25 2.29 0.48 18.98A037900200035
387. 13. A037900200036
38.92 7.67 2.22 0.44 19.46A037900200037
242. 12. A037900200038
39.86 5.1 1.7 0.29 19.93A037900200039
190. 9. A037900200040
42.86 4.72 0.65 0.26 21.43A037900200041
365. 53. A037900200042
46.74 7.31 0.63 0.39 23.37A037900200043
167. 141. A037900200044
48.72 5.44 0.34 0.28 24.36A037900200045
298. 278. A037900200046
ENDDATA 26 0 A037900200047
ENDSUBENT 46 0 A037900299999
ENDENTRY 2 0 A037999999999